[RFC,v2,3/3] kasan: add interceptors for all string functions

Commit Message

Christophe Leroy March 28, 2019, 3 p.m. UTC

In the same spirit as commit 393f203f5fd5 ("x86_64: kasan: add
interceptors for memset/memmove/memcpy functions"), this patch
adds interceptors for string manipulation functions so that we
can compile lib/string.o without kasan support hence allow the
string functions to also be used from places where kasan has
to be disabled.

Signed-off-by: Christophe Leroy <[e-mail]>
---
 v2: Fixed a few checkpatch stuff and added missing EXPORT_SYMBOL() and missing #undefs

 include/linux/string.h |  79 ++++++++++
 lib/Makefile           |   2 +
 lib/string.c           |   8 +
 mm/kasan/string.c      | 394 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 483 insertions(+)

Comments

Christophe Leroy April 2, 2019, 9:43 a.m. UTC | #1

Hi Dmitry, Andrey and others,

Do you have any comments to this series ?

I'd like to know if this approach is ok or if it is better to keep doing 
as in https://patchwork.ozlabs.org/patch/1055788/

Thanks
Christophe

Le 28/03/2019 à 16:00, Christophe Leroy a écrit :
> In the same spirit as commit 393f203f5fd5 ("x86_64: kasan: add
> interceptors for memset/memmove/memcpy functions"), this patch
> adds interceptors for string manipulation functions so that we
> can compile lib/string.o without kasan support hence allow the
> string functions to also be used from places where kasan has
> to be disabled.
> 
> Signed-off-by: Christophe Leroy <[e-mail]>
> ---
>   v2: Fixed a few checkpatch stuff and added missing EXPORT_SYMBOL() and missing #undefs
> 
>   include/linux/string.h |  79 ++++++++++
>   lib/Makefile           |   2 +
>   lib/string.c           |   8 +
>   mm/kasan/string.c      | 394 +++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 483 insertions(+)
> 
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 7927b875f80c..3d2aff2ed402 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -19,54 +19,117 @@ extern void *memdup_user_nul(const void __user *, size_t);
>    */
>   #include <asm/string.h>
>   
> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> +/*
> + * For files that are not instrumented (e.g. mm/slub.c) we
> + * should use not instrumented version of mem* functions.
> + */
> +#define memset16	__memset16
> +#define memset32	__memset32
> +#define memset64	__memset64
> +#define memzero_explicit	__memzero_explicit
> +#define strcpy		__strcpy
> +#define strncpy		__strncpy
> +#define strlcpy		__strlcpy
> +#define strscpy		__strscpy
> +#define strcat		__strcat
> +#define strncat		__strncat
> +#define strlcat		__strlcat
> +#define strcmp		__strcmp
> +#define strncmp		__strncmp
> +#define strcasecmp	__strcasecmp
> +#define strncasecmp	__strncasecmp
> +#define strchr		__strchr
> +#define strchrnul	__strchrnul
> +#define strrchr		__strrchr
> +#define strnchr		__strnchr
> +#define skip_spaces	__skip_spaces
> +#define strim		__strim
> +#define strstr		__strstr
> +#define strnstr		__strnstr
> +#define strlen		__strlen
> +#define strnlen		__strnlen
> +#define strpbrk		__strpbrk
> +#define strsep		__strsep
> +#define strspn		__strspn
> +#define strcspn		__strcspn
> +#define memscan		__memscan
> +#define memcmp		__memcmp
> +#define memchr		__memchr
> +#define memchr_inv	__memchr_inv
> +#define strreplace	__strreplace
> +
> +#ifndef __NO_FORTIFY
> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
> +#endif
> +
> +#endif
> +
>   #ifndef __HAVE_ARCH_STRCPY
>   extern char * strcpy(char *,const char *);
> +char *__strcpy(char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCPY
>   extern char * strncpy(char *,const char *, __kernel_size_t);
> +char *__strncpy(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLCPY
>   size_t strlcpy(char *, const char *, size_t);
> +size_t __strlcpy(char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRSCPY
>   ssize_t strscpy(char *, const char *, size_t);
> +ssize_t __strscpy(char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCAT
>   extern char * strcat(char *, const char *);
> +char *__strcat(char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCAT
>   extern char * strncat(char *, const char *, __kernel_size_t);
> +char *__strncat(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLCAT
>   extern size_t strlcat(char *, const char *, __kernel_size_t);
> +size_t __strlcat(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCMP
>   extern int strcmp(const char *,const char *);
> +int __strcmp(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCMP
>   extern int strncmp(const char *,const char *,__kernel_size_t);
> +int __strncmp(const char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCASECMP
>   extern int strcasecmp(const char *s1, const char *s2);
> +int __strcasecmp(const char *s1, const char *s2);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCASECMP
>   extern int strncasecmp(const char *s1, const char *s2, size_t n);
> +int __strncasecmp(const char *s1, const char *s2, size_t n);
>   #endif
>   #ifndef __HAVE_ARCH_STRCHR
>   extern char * strchr(const char *,int);
> +char *__strchr(const char *, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRCHRNUL
>   extern char * strchrnul(const char *,int);
> +char *__strchrnul(const char *, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCHR
>   extern char * strnchr(const char *, size_t, int);
> +char *__strnchr(const char *, size_t, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRRCHR
>   extern char * strrchr(const char *,int);
> +char *__strrchr(const char *, int);
>   #endif
>   extern char * __must_check skip_spaces(const char *);
> +char * __must_check __skip_spaces(const char *);
>   
>   extern char *strim(char *);
> +char *__strim(char *);
>   
>   static inline __must_check char *strstrip(char *str)
>   {
> @@ -75,27 +138,35 @@ static inline __must_check char *strstrip(char *str)
>   
>   #ifndef __HAVE_ARCH_STRSTR
>   extern char * strstr(const char *, const char *);
> +char *__strstr(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNSTR
>   extern char * strnstr(const char *, const char *, size_t);
> +char *__strnstr(const char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLEN
>   extern __kernel_size_t strlen(const char *);
> +__kernel_size_t __strlen(const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNLEN
>   extern __kernel_size_t strnlen(const char *,__kernel_size_t);
> +__kernel_size_t __strnlen(const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRPBRK
>   extern char * strpbrk(const char *,const char *);
> +char *__strpbrk(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRSEP
>   extern char * strsep(char **,const char *);
> +char *__strsep(char **, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRSPN
>   extern __kernel_size_t strspn(const char *,const char *);
> +__kernel_size_t __strspn(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRCSPN
>   extern __kernel_size_t strcspn(const char *,const char *);
> +__kernel_size_t __strcspn(const char *, const char *);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET
> @@ -104,14 +175,17 @@ extern void * memset(void *,int,__kernel_size_t);
>   
>   #ifndef __HAVE_ARCH_MEMSET16
>   extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
> +void *__memset16(uint16_t *, uint16_t, __kernel_size_t);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET32
>   extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
> +void *__memset32(uint32_t *, uint32_t, __kernel_size_t);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET64
>   extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
> +void *__memset64(uint64_t *, uint64_t, __kernel_size_t);
>   #endif
>   
>   static inline void *memset_l(unsigned long *p, unsigned long v,
> @@ -146,12 +220,15 @@ extern void * memmove(void *,const void *,__kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMSCAN
>   extern void * memscan(void *,int,__kernel_size_t);
> +void *__memscan(void *, int, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCMP
>   extern int memcmp(const void *,const void *,__kernel_size_t);
> +int __memcmp(const void *, const void *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCHR
>   extern void * memchr(const void *,int,__kernel_size_t);
> +void *__memchr(const void *, int, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCPY_MCSAFE
>   static inline __must_check unsigned long memcpy_mcsafe(void *dst,
> @@ -168,7 +245,9 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
>   }
>   #endif
>   void *memchr_inv(const void *s, int c, size_t n);
> +void *__memchr_inv(const void *s, int c, size_t n);
>   char *strreplace(char *s, char old, char new);
> +char *__strreplace(char *s, char old, char new);
>   
>   extern void kfree_const(const void *x);
>   
> diff --git a/lib/Makefile b/lib/Makefile
> index 30b9b0bfbba9..19d0237f9b9c 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -18,6 +18,8 @@ KCOV_INSTRUMENT_list_debug.o := n
>   KCOV_INSTRUMENT_debugobjects.o := n
>   KCOV_INSTRUMENT_dynamic_debug.o := n
>   
> +KASAN_SANITIZE_string.o := n
> +
>   lib-y := ctype.o string.o string_sysfs.o vsprintf.o cmdline.o \
>   	 rbtree.o radix-tree.o timerqueue.o xarray.o \
>   	 idr.o int_sqrt.o extable.o \
> diff --git a/lib/string.c b/lib/string.c
> index f3886c5175ac..31a253201bba 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -85,7 +85,9 @@ EXPORT_SYMBOL(strcasecmp);
>    * @dest: Where to copy the string to
>    * @src: Where to copy the string from
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcpy
> +#endif
>   char *strcpy(char *dest, const char *src)
>   {
>   	char *tmp = dest;
> @@ -243,7 +245,9 @@ EXPORT_SYMBOL(strscpy);
>    * @dest: The string to be appended to
>    * @src: The string to append to it
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcat
> +#endif
>   char *strcat(char *dest, const char *src)
>   {
>   	char *tmp = dest;
> @@ -319,7 +323,9 @@ EXPORT_SYMBOL(strlcat);
>    * @cs: One string
>    * @ct: Another string
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcmp
> +#endif
>   int strcmp(const char *cs, const char *ct)
>   {
>   	unsigned char c1, c2;
> @@ -773,7 +779,9 @@ EXPORT_SYMBOL(memmove);
>    * @ct: Another area of memory
>    * @count: The size of the area.
>    */
> +#ifndef CONFIG_KASAN
>   #undef memcmp
> +#endif
>   __visible int memcmp(const void *cs, const void *ct, size_t count)
>   {
>   	const unsigned char *su1, *su2;
> diff --git a/mm/kasan/string.c b/mm/kasan/string.c
> index 083b967255a2..0db31bbbf643 100644
> --- a/mm/kasan/string.c
> +++ b/mm/kasan/string.c
> @@ -35,6 +35,42 @@ void *memset(void *addr, int c, size_t len)
>   	return __memset(addr, c, len);
>   }
>   
> +#undef memset16
> +void *memset16(uint16_t *s, uint16_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 1, true, _RET_IP_);
> +
> +	return __memset16(s, v, count);
> +}
> +EXPORT_SYMBOL(memset16);
> +
> +#undef memset32
> +void *memset32(uint32_t *s, uint32_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 2, true, _RET_IP_);
> +
> +	return __memset32(s, v, count);
> +}
> +EXPORT_SYMBOL(memset32);
> +
> +#undef memset64
> +void *memset64(uint64_t *s, uint64_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 3, true, _RET_IP_);
> +
> +	return __memset64(s, v, count);
> +}
> +EXPORT_SYMBOL(memset64);
> +
> +#undef memzero_explicit
> +void memzero_explicit(void *s, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count, true, _RET_IP_);
> +
> +	return __memzero_explicit(s, count);
> +}
> +EXPORT_SYMBOL(memzero_explicit);
> +
>   #undef memmove
>   void *memmove(void *dest, const void *src, size_t len)
>   {
> @@ -52,3 +88,361 @@ void *memcpy(void *dest, const void *src, size_t len)
>   
>   	return __memcpy(dest, src, len);
>   }
> +
> +#undef strcpy
> +char *strcpy(char *dest, const char *src)
> +{
> +	size_t len = __strlen(src) + 1;
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> +
> +	return __strcpy(dest, src);
> +}
> +EXPORT_SYMBOL(strcpy);
> +
> +#undef strncpy
> +char *strncpy(char *dest, const char *src, size_t count)
> +{
> +	size_t len = min(__strlen(src) + 1, count);
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, count, true, _RET_IP_);
> +
> +	return __strncpy(dest, src, count);
> +}
> +EXPORT_SYMBOL(strncpy);
> +
> +#undef strlcpy
> +size_t strlcpy(char *dest, const char *src, size_t size)
> +{
> +	size_t len = __strlen(src) + 1;
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, min(len, size), true, _RET_IP_);
> +
> +	return __strlcpy(dest, src, size);
> +}
> +EXPORT_SYMBOL(strlcpy);
> +
> +#undef strscpy
> +ssize_t strscpy(char *dest, const char *src, size_t count)
> +{
> +	int len = min(__strlen(src) + 1, count);
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> +
> +	return __strscpy(dest, src, count);
> +}
> +EXPORT_SYMBOL(strscpy);
> +
> +#undef strcat
> +char *strcat(char *dest, const char *src)
> +{
> +	size_t slen = __strlen(src) + 1;
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strcat(dest, src);
> +}
> +EXPORT_SYMBOL(strcat);
> +
> +#undef strncat
> +char *strncat(char *dest, const char *src, size_t count)
> +{
> +	size_t slen = min(__strlen(src) + 1, count);
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strncat(dest, src, count);
> +}
> +EXPORT_SYMBOL(strncat);
> +
> +#undef strlcat
> +size_t strlcat(char *dest, const char *src, size_t count)
> +{
> +	size_t slen = min(__strlen(src) + 1, count);
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strlcat(dest, src, count);
> +}
> +EXPORT_SYMBOL(strlcat);
> +
> +#undef strcmp
> +int strcmp(const char *cs, const char *ct)
> +{
> +	size_t len = min(__strlen(cs) + 1, __strlen(ct) + 1);
> +
> +	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> +
> +	return __strcmp(cs, ct);
> +}
> +EXPORT_SYMBOL(strcmp);
> +
> +#undef strncmp
> +int strncmp(const char *cs, const char *ct, size_t count)
> +{
> +	size_t len = min3(__strlen(cs) + 1, __strlen(ct) + 1, count);
> +
> +	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> +
> +	return __strncmp(cs, ct, count);
> +}
> +EXPORT_SYMBOL(strncmp);
> +
> +#undef strcasecmp
> +int strcasecmp(const char *s1, const char *s2)
> +{
> +	size_t len = min(__strlen(s1) + 1, __strlen(s2) + 1);
> +
> +	check_memory_region((unsigned long)s1, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, len, false, _RET_IP_);
> +
> +	return __strcasecmp(s1, s2);
> +}
> +EXPORT_SYMBOL(strcasecmp);
> +
> +#undef strncasecmp
> +int strncasecmp(const char *s1, const char *s2, size_t len)
> +{
> +	size_t sz = min3(__strlen(s1) + 1, __strlen(s2) + 1, len);
> +
> +	check_memory_region((unsigned long)s1, sz, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, sz, false, _RET_IP_);
> +
> +	return __strncasecmp(s1, s2, len);
> +}
> +EXPORT_SYMBOL(strncasecmp);
> +
> +#undef strchr
> +char *strchr(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strchr(s, c);
> +}
> +EXPORT_SYMBOL(strchr);
> +
> +#undef strchrnul
> +char *strchrnul(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strchrnul(s, c);
> +}
> +EXPORT_SYMBOL(strchrnul);
> +
> +#undef strrchr
> +char *strrchr(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strrchr(s, c);
> +}
> +EXPORT_SYMBOL(strrchr);
> +
> +#undef strnchr
> +char *strnchr(const char *s, size_t count, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strnchr(s, count, c);
> +}
> +EXPORT_SYMBOL(strnchr);
> +
> +#undef skip_spaces
> +char *skip_spaces(const char *str)
> +{
> +	size_t len = __strlen(str) + 1;
> +
> +	check_memory_region((unsigned long)str, len, false, _RET_IP_);
> +
> +	return __skip_spaces(str);
> +}
> +EXPORT_SYMBOL(skip_spaces);
> +
> +#undef strim
> +char *strim(char *s)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strim(s);
> +}
> +EXPORT_SYMBOL(strim);
> +
> +#undef strstr
> +char *strstr(const char *s1, const char *s2)
> +{
> +	size_t l1 = __strlen(s1) + 1;
> +	size_t l2 = __strlen(s2) + 1;
> +
> +	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> +
> +	return __strstr(s1, s2);
> +}
> +EXPORT_SYMBOL(strstr);
> +
> +#undef strnstr
> +char *strnstr(const char *s1, const char *s2, size_t len)
> +{
> +	size_t l1 = min(__strlen(s1) + 1, len);
> +	size_t l2 = __strlen(s2) + 1;
> +
> +	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> +
> +	return __strnstr(s1, s2, len);
> +}
> +EXPORT_SYMBOL(strnstr);
> +
> +#undef strlen
> +size_t strlen(const char *s)
> +{
> +	size_t len = __strlen(s);
> +
> +	check_memory_region((unsigned long)s, len + 1, false, _RET_IP_);
> +
> +	return len;
> +}
> +EXPORT_SYMBOL(strlen);
> +
> +#undef strnlen
> +size_t strnlen(const char *s, size_t count)
> +{
> +	size_t len = __strnlen(s, count);
> +
> +	check_memory_region((unsigned long)s, min(len + 1, count), false, _RET_IP_);
> +
> +	return len;
> +}
> +EXPORT_SYMBOL(strnlen);
> +
> +#undef strpbrk
> +char *strpbrk(const char *cs, const char *ct)
> +{
> +	size_t ls = __strlen(cs) + 1;
> +	size_t lt = __strlen(ct) + 1;
> +
> +	check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> +
> +	return __strpbrk(cs, ct);
> +}
> +EXPORT_SYMBOL(strpbrk);
> +
> +#undef strsep
> +char *strsep(char **s, const char *ct)
> +{
> +	char *cs = *s;
> +
> +	check_memory_region((unsigned long)s, sizeof(*s), true, _RET_IP_);
> +
> +	if (cs) {
> +		int ls = __strlen(cs) + 1;
> +		int lt = __strlen(ct) + 1;
> +
> +		check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> +		check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> +	}
> +
> +	return __strsep(s, ct);
> +}
> +EXPORT_SYMBOL(strsep);
> +
> +#undef strspn
> +size_t strspn(const char *s, const char *accept)
> +{
> +	size_t ls = __strlen(s) + 1;
> +	size_t la = __strlen(accept) + 1;
> +
> +	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)accept, la, false, _RET_IP_);
> +
> +	return __strspn(s, accept);
> +}
> +EXPORT_SYMBOL(strspn);
> +
> +#undef strcspn
> +size_t strcspn(const char *s, const char *reject)
> +{
> +	size_t ls = __strlen(s) + 1;
> +	size_t lr = __strlen(reject) + 1;
> +
> +	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)reject, lr, false, _RET_IP_);
> +
> +	return __strcspn(s, reject);
> +}
> +EXPORT_SYMBOL(strcspn);
> +
> +#undef memscan
> +void *memscan(void *addr, int c, size_t size)
> +{
> +	check_memory_region((unsigned long)addr, size, false, _RET_IP_);
> +
> +	return __memscan(addr, c, size);
> +}
> +EXPORT_SYMBOL(memscan);
> +
> +#undef memcmp
> +int memcmp(const void *cs, const void *ct, size_t count)
> +{
> +	check_memory_region((unsigned long)cs, count, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, count, false, _RET_IP_);
> +
> +	return __memcmp(cs, ct, count);
> +}
> +EXPORT_SYMBOL(memcmp);
> +
> +#undef memchr
> +void *memchr(const void *s, int c, size_t n)
> +{
> +	check_memory_region((unsigned long)s, n, false, _RET_IP_);
> +
> +	return __memchr(s, c, n);
> +}
> +EXPORT_SYMBOL(memchr);
> +
> +#undef memchr_inv
> +void *memchr_inv(const void *start, int c, size_t bytes)
> +{
> +	check_memory_region((unsigned long)start, bytes, false, _RET_IP_);
> +
> +	return __memchr_inv(start, c, bytes);
> +}
> +EXPORT_SYMBOL(memchr_inv);
> +
> +#undef strreplace
> +char *strreplace(char *s, char old, char new)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, true, _RET_IP_);
> +
> +	return __strreplace(s, old, new);
> +}
> +EXPORT_SYMBOL(strreplace);
>

Dmitry Vyukov April 2, 2019, 12:58 p.m. UTC | #2

On Tue, Apr 2, 2019 at 11:43 AM Christophe Leroy
<[e-mail]> wrote:
>
> Hi Dmitry, Andrey and others,
>
> Do you have any comments to this series ?
>
> I'd like to know if this approach is ok or if it is better to keep doing
> as in https://patchwork.ozlabs.org/patch/1055788/

Hi Christophe,

Forking every kernel function does not look like a scalable approach
to me. There is not much special about str* functions. There is
something a bit special about memset/memcpy as compiler emits them for
struct set/copy.
Could powerpc do the same as x86 and map some shadow early enough
(before "prom")? Then we would not need anything of this? Sorry if we
already discussed this, I am losing context quickly.




> Thanks
> Christophe
>
> Le 28/03/2019 à 16:00, Christophe Leroy a écrit :
> > In the same spirit as commit 393f203f5fd5 ("x86_64: kasan: add
> > interceptors for memset/memmove/memcpy functions"), this patch
> > adds interceptors for string manipulation functions so that we
> > can compile lib/string.o without kasan support hence allow the
> > string functions to also be used from places where kasan has
> > to be disabled.
> >
> > Signed-off-by: Christophe Leroy <[e-mail]>
> > ---
> >   v2: Fixed a few checkpatch stuff and added missing EXPORT_SYMBOL() and missing #undefs
> >
> >   include/linux/string.h |  79 ++++++++++
> >   lib/Makefile           |   2 +
> >   lib/string.c           |   8 +
> >   mm/kasan/string.c      | 394 +++++++++++++++++++++++++++++++++++++++++++++++++
> >   4 files changed, 483 insertions(+)
> >
> > diff --git a/include/linux/string.h b/include/linux/string.h
> > index 7927b875f80c..3d2aff2ed402 100644
> > --- a/include/linux/string.h
> > +++ b/include/linux/string.h
> > @@ -19,54 +19,117 @@ extern void *memdup_user_nul(const void __user *, size_t);
> >    */
> >   #include <asm/string.h>
> >
> > +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> > +/*
> > + * For files that are not instrumented (e.g. mm/slub.c) we
> > + * should use not instrumented version of mem* functions.
> > + */
> > +#define memset16     __memset16
> > +#define memset32     __memset32
> > +#define memset64     __memset64
> > +#define memzero_explicit     __memzero_explicit
> > +#define strcpy               __strcpy
> > +#define strncpy              __strncpy
> > +#define strlcpy              __strlcpy
> > +#define strscpy              __strscpy
> > +#define strcat               __strcat
> > +#define strncat              __strncat
> > +#define strlcat              __strlcat
> > +#define strcmp               __strcmp
> > +#define strncmp              __strncmp
> > +#define strcasecmp   __strcasecmp
> > +#define strncasecmp  __strncasecmp
> > +#define strchr               __strchr
> > +#define strchrnul    __strchrnul
> > +#define strrchr              __strrchr
> > +#define strnchr              __strnchr
> > +#define skip_spaces  __skip_spaces
> > +#define strim                __strim
> > +#define strstr               __strstr
> > +#define strnstr              __strnstr
> > +#define strlen               __strlen
> > +#define strnlen              __strnlen
> > +#define strpbrk              __strpbrk
> > +#define strsep               __strsep
> > +#define strspn               __strspn
> > +#define strcspn              __strcspn
> > +#define memscan              __memscan
> > +#define memcmp               __memcmp
> > +#define memchr               __memchr
> > +#define memchr_inv   __memchr_inv
> > +#define strreplace   __strreplace
> > +
> > +#ifndef __NO_FORTIFY
> > +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
> > +#endif
> > +
> > +#endif
> > +
> >   #ifndef __HAVE_ARCH_STRCPY
> >   extern char * strcpy(char *,const char *);
> > +char *__strcpy(char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNCPY
> >   extern char * strncpy(char *,const char *, __kernel_size_t);
> > +char *__strncpy(char *, const char *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRLCPY
> >   size_t strlcpy(char *, const char *, size_t);
> > +size_t __strlcpy(char *, const char *, size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRSCPY
> >   ssize_t strscpy(char *, const char *, size_t);
> > +ssize_t __strscpy(char *, const char *, size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCAT
> >   extern char * strcat(char *, const char *);
> > +char *__strcat(char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNCAT
> >   extern char * strncat(char *, const char *, __kernel_size_t);
> > +char *__strncat(char *, const char *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRLCAT
> >   extern size_t strlcat(char *, const char *, __kernel_size_t);
> > +size_t __strlcat(char *, const char *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCMP
> >   extern int strcmp(const char *,const char *);
> > +int __strcmp(const char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNCMP
> >   extern int strncmp(const char *,const char *,__kernel_size_t);
> > +int __strncmp(const char *, const char *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCASECMP
> >   extern int strcasecmp(const char *s1, const char *s2);
> > +int __strcasecmp(const char *s1, const char *s2);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNCASECMP
> >   extern int strncasecmp(const char *s1, const char *s2, size_t n);
> > +int __strncasecmp(const char *s1, const char *s2, size_t n);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCHR
> >   extern char * strchr(const char *,int);
> > +char *__strchr(const char *, int);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCHRNUL
> >   extern char * strchrnul(const char *,int);
> > +char *__strchrnul(const char *, int);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNCHR
> >   extern char * strnchr(const char *, size_t, int);
> > +char *__strnchr(const char *, size_t, int);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRRCHR
> >   extern char * strrchr(const char *,int);
> > +char *__strrchr(const char *, int);
> >   #endif
> >   extern char * __must_check skip_spaces(const char *);
> > +char * __must_check __skip_spaces(const char *);
> >
> >   extern char *strim(char *);
> > +char *__strim(char *);
> >
> >   static inline __must_check char *strstrip(char *str)
> >   {
> > @@ -75,27 +138,35 @@ static inline __must_check char *strstrip(char *str)
> >
> >   #ifndef __HAVE_ARCH_STRSTR
> >   extern char * strstr(const char *, const char *);
> > +char *__strstr(const char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNSTR
> >   extern char * strnstr(const char *, const char *, size_t);
> > +char *__strnstr(const char *, const char *, size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRLEN
> >   extern __kernel_size_t strlen(const char *);
> > +__kernel_size_t __strlen(const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRNLEN
> >   extern __kernel_size_t strnlen(const char *,__kernel_size_t);
> > +__kernel_size_t __strnlen(const char *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRPBRK
> >   extern char * strpbrk(const char *,const char *);
> > +char *__strpbrk(const char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRSEP
> >   extern char * strsep(char **,const char *);
> > +char *__strsep(char **, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRSPN
> >   extern __kernel_size_t strspn(const char *,const char *);
> > +__kernel_size_t __strspn(const char *, const char *);
> >   #endif
> >   #ifndef __HAVE_ARCH_STRCSPN
> >   extern __kernel_size_t strcspn(const char *,const char *);
> > +__kernel_size_t __strcspn(const char *, const char *);
> >   #endif
> >
> >   #ifndef __HAVE_ARCH_MEMSET
> > @@ -104,14 +175,17 @@ extern void * memset(void *,int,__kernel_size_t);
> >
> >   #ifndef __HAVE_ARCH_MEMSET16
> >   extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
> > +void *__memset16(uint16_t *, uint16_t, __kernel_size_t);
> >   #endif
> >
> >   #ifndef __HAVE_ARCH_MEMSET32
> >   extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
> > +void *__memset32(uint32_t *, uint32_t, __kernel_size_t);
> >   #endif
> >
> >   #ifndef __HAVE_ARCH_MEMSET64
> >   extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
> > +void *__memset64(uint64_t *, uint64_t, __kernel_size_t);
> >   #endif
> >
> >   static inline void *memset_l(unsigned long *p, unsigned long v,
> > @@ -146,12 +220,15 @@ extern void * memmove(void *,const void *,__kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_MEMSCAN
> >   extern void * memscan(void *,int,__kernel_size_t);
> > +void *__memscan(void *, int, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_MEMCMP
> >   extern int memcmp(const void *,const void *,__kernel_size_t);
> > +int __memcmp(const void *, const void *, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_MEMCHR
> >   extern void * memchr(const void *,int,__kernel_size_t);
> > +void *__memchr(const void *, int, __kernel_size_t);
> >   #endif
> >   #ifndef __HAVE_ARCH_MEMCPY_MCSAFE
> >   static inline __must_check unsigned long memcpy_mcsafe(void *dst,
> > @@ -168,7 +245,9 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
> >   }
> >   #endif
> >   void *memchr_inv(const void *s, int c, size_t n);
> > +void *__memchr_inv(const void *s, int c, size_t n);
> >   char *strreplace(char *s, char old, char new);
> > +char *__strreplace(char *s, char old, char new);
> >
> >   extern void kfree_const(const void *x);
> >
> > diff --git a/lib/Makefile b/lib/Makefile
> > index 30b9b0bfbba9..19d0237f9b9c 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -18,6 +18,8 @@ KCOV_INSTRUMENT_list_debug.o := n
> >   KCOV_INSTRUMENT_debugobjects.o := n
> >   KCOV_INSTRUMENT_dynamic_debug.o := n
> >
> > +KASAN_SANITIZE_string.o := n
> > +
> >   lib-y := ctype.o string.o string_sysfs.o vsprintf.o cmdline.o \
> >        rbtree.o radix-tree.o timerqueue.o xarray.o \
> >        idr.o int_sqrt.o extable.o \
> > diff --git a/lib/string.c b/lib/string.c
> > index f3886c5175ac..31a253201bba 100644
> > --- a/lib/string.c
> > +++ b/lib/string.c
> > @@ -85,7 +85,9 @@ EXPORT_SYMBOL(strcasecmp);
> >    * @dest: Where to copy the string to
> >    * @src: Where to copy the string from
> >    */
> > +#ifndef CONFIG_KASAN
> >   #undef strcpy
> > +#endif
> >   char *strcpy(char *dest, const char *src)
> >   {
> >       char *tmp = dest;
> > @@ -243,7 +245,9 @@ EXPORT_SYMBOL(strscpy);
> >    * @dest: The string to be appended to
> >    * @src: The string to append to it
> >    */
> > +#ifndef CONFIG_KASAN
> >   #undef strcat
> > +#endif
> >   char *strcat(char *dest, const char *src)
> >   {
> >       char *tmp = dest;
> > @@ -319,7 +323,9 @@ EXPORT_SYMBOL(strlcat);
> >    * @cs: One string
> >    * @ct: Another string
> >    */
> > +#ifndef CONFIG_KASAN
> >   #undef strcmp
> > +#endif
> >   int strcmp(const char *cs, const char *ct)
> >   {
> >       unsigned char c1, c2;
> > @@ -773,7 +779,9 @@ EXPORT_SYMBOL(memmove);
> >    * @ct: Another area of memory
> >    * @count: The size of the area.
> >    */
> > +#ifndef CONFIG_KASAN
> >   #undef memcmp
> > +#endif
> >   __visible int memcmp(const void *cs, const void *ct, size_t count)
> >   {
> >       const unsigned char *su1, *su2;
> > diff --git a/mm/kasan/string.c b/mm/kasan/string.c
> > index 083b967255a2..0db31bbbf643 100644
> > --- a/mm/kasan/string.c
> > +++ b/mm/kasan/string.c
> > @@ -35,6 +35,42 @@ void *memset(void *addr, int c, size_t len)
> >       return __memset(addr, c, len);
> >   }
> >
> > +#undef memset16
> > +void *memset16(uint16_t *s, uint16_t v, size_t count)
> > +{
> > +     check_memory_region((unsigned long)s, count << 1, true, _RET_IP_);
> > +
> > +     return __memset16(s, v, count);
> > +}
> > +EXPORT_SYMBOL(memset16);
> > +
> > +#undef memset32
> > +void *memset32(uint32_t *s, uint32_t v, size_t count)
> > +{
> > +     check_memory_region((unsigned long)s, count << 2, true, _RET_IP_);
> > +
> > +     return __memset32(s, v, count);
> > +}
> > +EXPORT_SYMBOL(memset32);
> > +
> > +#undef memset64
> > +void *memset64(uint64_t *s, uint64_t v, size_t count)
> > +{
> > +     check_memory_region((unsigned long)s, count << 3, true, _RET_IP_);
> > +
> > +     return __memset64(s, v, count);
> > +}
> > +EXPORT_SYMBOL(memset64);
> > +
> > +#undef memzero_explicit
> > +void memzero_explicit(void *s, size_t count)
> > +{
> > +     check_memory_region((unsigned long)s, count, true, _RET_IP_);
> > +
> > +     return __memzero_explicit(s, count);
> > +}
> > +EXPORT_SYMBOL(memzero_explicit);
> > +
> >   #undef memmove
> >   void *memmove(void *dest, const void *src, size_t len)
> >   {
> > @@ -52,3 +88,361 @@ void *memcpy(void *dest, const void *src, size_t len)
> >
> >       return __memcpy(dest, src, len);
> >   }
> > +
> > +#undef strcpy
> > +char *strcpy(char *dest, const char *src)
> > +{
> > +     size_t len = __strlen(src) + 1;
> > +
> > +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > +
> > +     return __strcpy(dest, src);
> > +}
> > +EXPORT_SYMBOL(strcpy);
> > +
> > +#undef strncpy
> > +char *strncpy(char *dest, const char *src, size_t count)
> > +{
> > +     size_t len = min(__strlen(src) + 1, count);
> > +
> > +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, count, true, _RET_IP_);
> > +
> > +     return __strncpy(dest, src, count);
> > +}
> > +EXPORT_SYMBOL(strncpy);
> > +
> > +#undef strlcpy
> > +size_t strlcpy(char *dest, const char *src, size_t size)
> > +{
> > +     size_t len = __strlen(src) + 1;
> > +
> > +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, min(len, size), true, _RET_IP_);
> > +
> > +     return __strlcpy(dest, src, size);
> > +}
> > +EXPORT_SYMBOL(strlcpy);
> > +
> > +#undef strscpy
> > +ssize_t strscpy(char *dest, const char *src, size_t count)
> > +{
> > +     int len = min(__strlen(src) + 1, count);
> > +
> > +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > +
> > +     return __strscpy(dest, src, count);
> > +}
> > +EXPORT_SYMBOL(strscpy);
> > +
> > +#undef strcat
> > +char *strcat(char *dest, const char *src)
> > +{
> > +     size_t slen = __strlen(src) + 1;
> > +     size_t dlen = __strlen(dest);
> > +
> > +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> > +
> > +     return __strcat(dest, src);
> > +}
> > +EXPORT_SYMBOL(strcat);
> > +
> > +#undef strncat
> > +char *strncat(char *dest, const char *src, size_t count)
> > +{
> > +     size_t slen = min(__strlen(src) + 1, count);
> > +     size_t dlen = __strlen(dest);
> > +
> > +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> > +
> > +     return __strncat(dest, src, count);
> > +}
> > +EXPORT_SYMBOL(strncat);
> > +
> > +#undef strlcat
> > +size_t strlcat(char *dest, const char *src, size_t count)
> > +{
> > +     size_t slen = min(__strlen(src) + 1, count);
> > +     size_t dlen = __strlen(dest);
> > +
> > +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> > +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> > +
> > +     return __strlcat(dest, src, count);
> > +}
> > +EXPORT_SYMBOL(strlcat);
> > +
> > +#undef strcmp
> > +int strcmp(const char *cs, const char *ct)
> > +{
> > +     size_t len = min(__strlen(cs) + 1, __strlen(ct) + 1);
> > +
> > +     check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> > +
> > +     return __strcmp(cs, ct);
> > +}
> > +EXPORT_SYMBOL(strcmp);
> > +
> > +#undef strncmp
> > +int strncmp(const char *cs, const char *ct, size_t count)
> > +{
> > +     size_t len = min3(__strlen(cs) + 1, __strlen(ct) + 1, count);
> > +
> > +     check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> > +
> > +     return __strncmp(cs, ct, count);
> > +}
> > +EXPORT_SYMBOL(strncmp);
> > +
> > +#undef strcasecmp
> > +int strcasecmp(const char *s1, const char *s2)
> > +{
> > +     size_t len = min(__strlen(s1) + 1, __strlen(s2) + 1);
> > +
> > +     check_memory_region((unsigned long)s1, len, false, _RET_IP_);
> > +     check_memory_region((unsigned long)s2, len, false, _RET_IP_);
> > +
> > +     return __strcasecmp(s1, s2);
> > +}
> > +EXPORT_SYMBOL(strcasecmp);
> > +
> > +#undef strncasecmp
> > +int strncasecmp(const char *s1, const char *s2, size_t len)
> > +{
> > +     size_t sz = min3(__strlen(s1) + 1, __strlen(s2) + 1, len);
> > +
> > +     check_memory_region((unsigned long)s1, sz, false, _RET_IP_);
> > +     check_memory_region((unsigned long)s2, sz, false, _RET_IP_);
> > +
> > +     return __strncasecmp(s1, s2, len);
> > +}
> > +EXPORT_SYMBOL(strncasecmp);
> > +
> > +#undef strchr
> > +char *strchr(const char *s, int c)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
> > +
> > +     return __strchr(s, c);
> > +}
> > +EXPORT_SYMBOL(strchr);
> > +
> > +#undef strchrnul
> > +char *strchrnul(const char *s, int c)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
> > +
> > +     return __strchrnul(s, c);
> > +}
> > +EXPORT_SYMBOL(strchrnul);
> > +
> > +#undef strrchr
> > +char *strrchr(const char *s, int c)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
> > +
> > +     return __strrchr(s, c);
> > +}
> > +EXPORT_SYMBOL(strrchr);
> > +
> > +#undef strnchr
> > +char *strnchr(const char *s, size_t count, int c)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
> > +
> > +     return __strnchr(s, count, c);
> > +}
> > +EXPORT_SYMBOL(strnchr);
> > +
> > +#undef skip_spaces
> > +char *skip_spaces(const char *str)
> > +{
> > +     size_t len = __strlen(str) + 1;
> > +
> > +     check_memory_region((unsigned long)str, len, false, _RET_IP_);
> > +
> > +     return __skip_spaces(str);
> > +}
> > +EXPORT_SYMBOL(skip_spaces);
> > +
> > +#undef strim
> > +char *strim(char *s)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
> > +
> > +     return __strim(s);
> > +}
> > +EXPORT_SYMBOL(strim);
> > +
> > +#undef strstr
> > +char *strstr(const char *s1, const char *s2)
> > +{
> > +     size_t l1 = __strlen(s1) + 1;
> > +     size_t l2 = __strlen(s2) + 1;
> > +
> > +     check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> > +     check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> > +
> > +     return __strstr(s1, s2);
> > +}
> > +EXPORT_SYMBOL(strstr);
> > +
> > +#undef strnstr
> > +char *strnstr(const char *s1, const char *s2, size_t len)
> > +{
> > +     size_t l1 = min(__strlen(s1) + 1, len);
> > +     size_t l2 = __strlen(s2) + 1;
> > +
> > +     check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> > +     check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> > +
> > +     return __strnstr(s1, s2, len);
> > +}
> > +EXPORT_SYMBOL(strnstr);
> > +
> > +#undef strlen
> > +size_t strlen(const char *s)
> > +{
> > +     size_t len = __strlen(s);
> > +
> > +     check_memory_region((unsigned long)s, len + 1, false, _RET_IP_);
> > +
> > +     return len;
> > +}
> > +EXPORT_SYMBOL(strlen);
> > +
> > +#undef strnlen
> > +size_t strnlen(const char *s, size_t count)
> > +{
> > +     size_t len = __strnlen(s, count);
> > +
> > +     check_memory_region((unsigned long)s, min(len + 1, count), false, _RET_IP_);
> > +
> > +     return len;
> > +}
> > +EXPORT_SYMBOL(strnlen);
> > +
> > +#undef strpbrk
> > +char *strpbrk(const char *cs, const char *ct)
> > +{
> > +     size_t ls = __strlen(cs) + 1;
> > +     size_t lt = __strlen(ct) + 1;
> > +
> > +     check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> > +     check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> > +
> > +     return __strpbrk(cs, ct);
> > +}
> > +EXPORT_SYMBOL(strpbrk);
> > +
> > +#undef strsep
> > +char *strsep(char **s, const char *ct)
> > +{
> > +     char *cs = *s;
> > +
> > +     check_memory_region((unsigned long)s, sizeof(*s), true, _RET_IP_);
> > +
> > +     if (cs) {
> > +             int ls = __strlen(cs) + 1;
> > +             int lt = __strlen(ct) + 1;
> > +
> > +             check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> > +             check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> > +     }
> > +
> > +     return __strsep(s, ct);
> > +}
> > +EXPORT_SYMBOL(strsep);
> > +
> > +#undef strspn
> > +size_t strspn(const char *s, const char *accept)
> > +{
> > +     size_t ls = __strlen(s) + 1;
> > +     size_t la = __strlen(accept) + 1;
> > +
> > +     check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> > +     check_memory_region((unsigned long)accept, la, false, _RET_IP_);
> > +
> > +     return __strspn(s, accept);
> > +}
> > +EXPORT_SYMBOL(strspn);
> > +
> > +#undef strcspn
> > +size_t strcspn(const char *s, const char *reject)
> > +{
> > +     size_t ls = __strlen(s) + 1;
> > +     size_t lr = __strlen(reject) + 1;
> > +
> > +     check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> > +     check_memory_region((unsigned long)reject, lr, false, _RET_IP_);
> > +
> > +     return __strcspn(s, reject);
> > +}
> > +EXPORT_SYMBOL(strcspn);
> > +
> > +#undef memscan
> > +void *memscan(void *addr, int c, size_t size)
> > +{
> > +     check_memory_region((unsigned long)addr, size, false, _RET_IP_);
> > +
> > +     return __memscan(addr, c, size);
> > +}
> > +EXPORT_SYMBOL(memscan);
> > +
> > +#undef memcmp
> > +int memcmp(const void *cs, const void *ct, size_t count)
> > +{
> > +     check_memory_region((unsigned long)cs, count, false, _RET_IP_);
> > +     check_memory_region((unsigned long)ct, count, false, _RET_IP_);
> > +
> > +     return __memcmp(cs, ct, count);
> > +}
> > +EXPORT_SYMBOL(memcmp);
> > +
> > +#undef memchr
> > +void *memchr(const void *s, int c, size_t n)
> > +{
> > +     check_memory_region((unsigned long)s, n, false, _RET_IP_);
> > +
> > +     return __memchr(s, c, n);
> > +}
> > +EXPORT_SYMBOL(memchr);
> > +
> > +#undef memchr_inv
> > +void *memchr_inv(const void *start, int c, size_t bytes)
> > +{
> > +     check_memory_region((unsigned long)start, bytes, false, _RET_IP_);
> > +
> > +     return __memchr_inv(start, c, bytes);
> > +}
> > +EXPORT_SYMBOL(memchr_inv);
> > +
> > +#undef strreplace
> > +char *strreplace(char *s, char old, char new)
> > +{
> > +     size_t len = __strlen(s) + 1;
> > +
> > +     check_memory_region((unsigned long)s, len, true, _RET_IP_);
> > +
> > +     return __strreplace(s, old, new);
> > +}
> > +EXPORT_SYMBOL(strreplace);
> >

Christophe Leroy April 2, 2019, 2:57 p.m. UTC | #3

Le 02/04/2019 à 14:58, Dmitry Vyukov a écrit :
> On Tue, Apr 2, 2019 at 11:43 AM Christophe Leroy
> <[e-mail]> wrote:
>>
>> Hi Dmitry, Andrey and others,
>>
>> Do you have any comments to this series ?
>>
>> I'd like to know if this approach is ok or if it is better to keep doing
>> as in https://patchwork.ozlabs.org/patch/1055788/
> 
> Hi Christophe,
> 
> Forking every kernel function does not look like a scalable approach
> to me. There is not much special about str* functions. There is
> something a bit special about memset/memcpy as compiler emits them for
> struct set/copy.
> Could powerpc do the same as x86 and map some shadow early enough
> (before "prom")? Then we would not need anything of this? Sorry if we
> already discussed this, I am losing context quickly.

Hi Dmitry,

I'm afraid we can't map shadow ram that early. This code gets run by 
third party BIOS SW which manages the MMU and provides a 1:1 mapping, so 
there is no way we can map shadow memory.

If you feel providing interceptors for the string functions is not a 
good idea, I'm ok with it, I'll keep the necessary string functions in 
prom_init.c

I was proposing the interceptor's approach because behind the specific 
need for handling early prom_init code, I thought it was also a way to 
limit KASAN performance impact on string functions, and it was also a 
way to handle all the optimised string functions provided by architectures.
In my series I have a patch that disables powerpc's optimised string 
functions (https://patchwork.ozlabs.org/patch/1055780/). The 
interceptor's approach was a way to avoid that. As far as I can see, at 
the time being the other arches don't disable their optimised string 
functions, meaning the KASAN checks are skipped.

Thanks
Christophe

> 
> 
> 
> 
>> Thanks
>> Christophe
>>
>> Le 28/03/2019 à 16:00, Christophe Leroy a écrit :
>>> In the same spirit as commit 393f203f5fd5 ("x86_64: kasan: add
>>> interceptors for memset/memmove/memcpy functions"), this patch
>>> adds interceptors for string manipulation functions so that we
>>> can compile lib/string.o without kasan support hence allow the
>>> string functions to also be used from places where kasan has
>>> to be disabled.
>>>
>>> Signed-off-by: Christophe Leroy <[e-mail]>
>>> ---
>>>    v2: Fixed a few checkpatch stuff and added missing EXPORT_SYMBOL() and missing #undefs
>>>
>>>    include/linux/string.h |  79 ++++++++++
>>>    lib/Makefile           |   2 +
>>>    lib/string.c           |   8 +
>>>    mm/kasan/string.c      | 394 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>    4 files changed, 483 insertions(+)
>>>
>>> diff --git a/include/linux/string.h b/include/linux/string.h
>>> index 7927b875f80c..3d2aff2ed402 100644
>>> --- a/include/linux/string.h
>>> +++ b/include/linux/string.h
>>> @@ -19,54 +19,117 @@ extern void *memdup_user_nul(const void __user *, size_t);
>>>     */
>>>    #include <asm/string.h>
>>>
>>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>>> +/*
>>> + * For files that are not instrumented (e.g. mm/slub.c) we
>>> + * should use not instrumented version of mem* functions.
>>> + */
>>> +#define memset16     __memset16
>>> +#define memset32     __memset32
>>> +#define memset64     __memset64
>>> +#define memzero_explicit     __memzero_explicit
>>> +#define strcpy               __strcpy
>>> +#define strncpy              __strncpy
>>> +#define strlcpy              __strlcpy
>>> +#define strscpy              __strscpy
>>> +#define strcat               __strcat
>>> +#define strncat              __strncat
>>> +#define strlcat              __strlcat
>>> +#define strcmp               __strcmp
>>> +#define strncmp              __strncmp
>>> +#define strcasecmp   __strcasecmp
>>> +#define strncasecmp  __strncasecmp
>>> +#define strchr               __strchr
>>> +#define strchrnul    __strchrnul
>>> +#define strrchr              __strrchr
>>> +#define strnchr              __strnchr
>>> +#define skip_spaces  __skip_spaces
>>> +#define strim                __strim
>>> +#define strstr               __strstr
>>> +#define strnstr              __strnstr
>>> +#define strlen               __strlen
>>> +#define strnlen              __strnlen
>>> +#define strpbrk              __strpbrk
>>> +#define strsep               __strsep
>>> +#define strspn               __strspn
>>> +#define strcspn              __strcspn
>>> +#define memscan              __memscan
>>> +#define memcmp               __memcmp
>>> +#define memchr               __memchr
>>> +#define memchr_inv   __memchr_inv
>>> +#define strreplace   __strreplace
>>> +
>>> +#ifndef __NO_FORTIFY
>>> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
>>> +#endif
>>> +
>>> +#endif
>>> +
>>>    #ifndef __HAVE_ARCH_STRCPY
>>>    extern char * strcpy(char *,const char *);
>>> +char *__strcpy(char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNCPY
>>>    extern char * strncpy(char *,const char *, __kernel_size_t);
>>> +char *__strncpy(char *, const char *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRLCPY
>>>    size_t strlcpy(char *, const char *, size_t);
>>> +size_t __strlcpy(char *, const char *, size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRSCPY
>>>    ssize_t strscpy(char *, const char *, size_t);
>>> +ssize_t __strscpy(char *, const char *, size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCAT
>>>    extern char * strcat(char *, const char *);
>>> +char *__strcat(char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNCAT
>>>    extern char * strncat(char *, const char *, __kernel_size_t);
>>> +char *__strncat(char *, const char *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRLCAT
>>>    extern size_t strlcat(char *, const char *, __kernel_size_t);
>>> +size_t __strlcat(char *, const char *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCMP
>>>    extern int strcmp(const char *,const char *);
>>> +int __strcmp(const char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNCMP
>>>    extern int strncmp(const char *,const char *,__kernel_size_t);
>>> +int __strncmp(const char *, const char *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCASECMP
>>>    extern int strcasecmp(const char *s1, const char *s2);
>>> +int __strcasecmp(const char *s1, const char *s2);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNCASECMP
>>>    extern int strncasecmp(const char *s1, const char *s2, size_t n);
>>> +int __strncasecmp(const char *s1, const char *s2, size_t n);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCHR
>>>    extern char * strchr(const char *,int);
>>> +char *__strchr(const char *, int);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCHRNUL
>>>    extern char * strchrnul(const char *,int);
>>> +char *__strchrnul(const char *, int);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNCHR
>>>    extern char * strnchr(const char *, size_t, int);
>>> +char *__strnchr(const char *, size_t, int);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRRCHR
>>>    extern char * strrchr(const char *,int);
>>> +char *__strrchr(const char *, int);
>>>    #endif
>>>    extern char * __must_check skip_spaces(const char *);
>>> +char * __must_check __skip_spaces(const char *);
>>>
>>>    extern char *strim(char *);
>>> +char *__strim(char *);
>>>
>>>    static inline __must_check char *strstrip(char *str)
>>>    {
>>> @@ -75,27 +138,35 @@ static inline __must_check char *strstrip(char *str)
>>>
>>>    #ifndef __HAVE_ARCH_STRSTR
>>>    extern char * strstr(const char *, const char *);
>>> +char *__strstr(const char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNSTR
>>>    extern char * strnstr(const char *, const char *, size_t);
>>> +char *__strnstr(const char *, const char *, size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRLEN
>>>    extern __kernel_size_t strlen(const char *);
>>> +__kernel_size_t __strlen(const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRNLEN
>>>    extern __kernel_size_t strnlen(const char *,__kernel_size_t);
>>> +__kernel_size_t __strnlen(const char *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRPBRK
>>>    extern char * strpbrk(const char *,const char *);
>>> +char *__strpbrk(const char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRSEP
>>>    extern char * strsep(char **,const char *);
>>> +char *__strsep(char **, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRSPN
>>>    extern __kernel_size_t strspn(const char *,const char *);
>>> +__kernel_size_t __strspn(const char *, const char *);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_STRCSPN
>>>    extern __kernel_size_t strcspn(const char *,const char *);
>>> +__kernel_size_t __strcspn(const char *, const char *);
>>>    #endif
>>>
>>>    #ifndef __HAVE_ARCH_MEMSET
>>> @@ -104,14 +175,17 @@ extern void * memset(void *,int,__kernel_size_t);
>>>
>>>    #ifndef __HAVE_ARCH_MEMSET16
>>>    extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
>>> +void *__memset16(uint16_t *, uint16_t, __kernel_size_t);
>>>    #endif
>>>
>>>    #ifndef __HAVE_ARCH_MEMSET32
>>>    extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
>>> +void *__memset32(uint32_t *, uint32_t, __kernel_size_t);
>>>    #endif
>>>
>>>    #ifndef __HAVE_ARCH_MEMSET64
>>>    extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
>>> +void *__memset64(uint64_t *, uint64_t, __kernel_size_t);
>>>    #endif
>>>
>>>    static inline void *memset_l(unsigned long *p, unsigned long v,
>>> @@ -146,12 +220,15 @@ extern void * memmove(void *,const void *,__kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_MEMSCAN
>>>    extern void * memscan(void *,int,__kernel_size_t);
>>> +void *__memscan(void *, int, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_MEMCMP
>>>    extern int memcmp(const void *,const void *,__kernel_size_t);
>>> +int __memcmp(const void *, const void *, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_MEMCHR
>>>    extern void * memchr(const void *,int,__kernel_size_t);
>>> +void *__memchr(const void *, int, __kernel_size_t);
>>>    #endif
>>>    #ifndef __HAVE_ARCH_MEMCPY_MCSAFE
>>>    static inline __must_check unsigned long memcpy_mcsafe(void *dst,
>>> @@ -168,7 +245,9 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
>>>    }
>>>    #endif
>>>    void *memchr_inv(const void *s, int c, size_t n);
>>> +void *__memchr_inv(const void *s, int c, size_t n);
>>>    char *strreplace(char *s, char old, char new);
>>> +char *__strreplace(char *s, char old, char new);
>>>
>>>    extern void kfree_const(const void *x);
>>>
>>> diff --git a/lib/Makefile b/lib/Makefile
>>> index 30b9b0bfbba9..19d0237f9b9c 100644
>>> --- a/lib/Makefile
>>> +++ b/lib/Makefile
>>> @@ -18,6 +18,8 @@ KCOV_INSTRUMENT_list_debug.o := n
>>>    KCOV_INSTRUMENT_debugobjects.o := n
>>>    KCOV_INSTRUMENT_dynamic_debug.o := n
>>>
>>> +KASAN_SANITIZE_string.o := n
>>> +
>>>    lib-y := ctype.o string.o string_sysfs.o vsprintf.o cmdline.o \
>>>         rbtree.o radix-tree.o timerqueue.o xarray.o \
>>>         idr.o int_sqrt.o extable.o \
>>> diff --git a/lib/string.c b/lib/string.c
>>> index f3886c5175ac..31a253201bba 100644
>>> --- a/lib/string.c
>>> +++ b/lib/string.c
>>> @@ -85,7 +85,9 @@ EXPORT_SYMBOL(strcasecmp);
>>>     * @dest: Where to copy the string to
>>>     * @src: Where to copy the string from
>>>     */
>>> +#ifndef CONFIG_KASAN
>>>    #undef strcpy
>>> +#endif
>>>    char *strcpy(char *dest, const char *src)
>>>    {
>>>        char *tmp = dest;
>>> @@ -243,7 +245,9 @@ EXPORT_SYMBOL(strscpy);
>>>     * @dest: The string to be appended to
>>>     * @src: The string to append to it
>>>     */
>>> +#ifndef CONFIG_KASAN
>>>    #undef strcat
>>> +#endif
>>>    char *strcat(char *dest, const char *src)
>>>    {
>>>        char *tmp = dest;
>>> @@ -319,7 +323,9 @@ EXPORT_SYMBOL(strlcat);
>>>     * @cs: One string
>>>     * @ct: Another string
>>>     */
>>> +#ifndef CONFIG_KASAN
>>>    #undef strcmp
>>> +#endif
>>>    int strcmp(const char *cs, const char *ct)
>>>    {
>>>        unsigned char c1, c2;
>>> @@ -773,7 +779,9 @@ EXPORT_SYMBOL(memmove);
>>>     * @ct: Another area of memory
>>>     * @count: The size of the area.
>>>     */
>>> +#ifndef CONFIG_KASAN
>>>    #undef memcmp
>>> +#endif
>>>    __visible int memcmp(const void *cs, const void *ct, size_t count)
>>>    {
>>>        const unsigned char *su1, *su2;
>>> diff --git a/mm/kasan/string.c b/mm/kasan/string.c
>>> index 083b967255a2..0db31bbbf643 100644
>>> --- a/mm/kasan/string.c
>>> +++ b/mm/kasan/string.c
>>> @@ -35,6 +35,42 @@ void *memset(void *addr, int c, size_t len)
>>>        return __memset(addr, c, len);
>>>    }
>>>
>>> +#undef memset16
>>> +void *memset16(uint16_t *s, uint16_t v, size_t count)
>>> +{
>>> +     check_memory_region((unsigned long)s, count << 1, true, _RET_IP_);
>>> +
>>> +     return __memset16(s, v, count);
>>> +}
>>> +EXPORT_SYMBOL(memset16);
>>> +
>>> +#undef memset32
>>> +void *memset32(uint32_t *s, uint32_t v, size_t count)
>>> +{
>>> +     check_memory_region((unsigned long)s, count << 2, true, _RET_IP_);
>>> +
>>> +     return __memset32(s, v, count);
>>> +}
>>> +EXPORT_SYMBOL(memset32);
>>> +
>>> +#undef memset64
>>> +void *memset64(uint64_t *s, uint64_t v, size_t count)
>>> +{
>>> +     check_memory_region((unsigned long)s, count << 3, true, _RET_IP_);
>>> +
>>> +     return __memset64(s, v, count);
>>> +}
>>> +EXPORT_SYMBOL(memset64);
>>> +
>>> +#undef memzero_explicit
>>> +void memzero_explicit(void *s, size_t count)
>>> +{
>>> +     check_memory_region((unsigned long)s, count, true, _RET_IP_);
>>> +
>>> +     return __memzero_explicit(s, count);
>>> +}
>>> +EXPORT_SYMBOL(memzero_explicit);
>>> +
>>>    #undef memmove
>>>    void *memmove(void *dest, const void *src, size_t len)
>>>    {
>>> @@ -52,3 +88,361 @@ void *memcpy(void *dest, const void *src, size_t len)
>>>
>>>        return __memcpy(dest, src, len);
>>>    }
>>> +
>>> +#undef strcpy
>>> +char *strcpy(char *dest, const char *src)
>>> +{
>>> +     size_t len = __strlen(src) + 1;
>>> +
>>> +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, len, true, _RET_IP_);
>>> +
>>> +     return __strcpy(dest, src);
>>> +}
>>> +EXPORT_SYMBOL(strcpy);
>>> +
>>> +#undef strncpy
>>> +char *strncpy(char *dest, const char *src, size_t count)
>>> +{
>>> +     size_t len = min(__strlen(src) + 1, count);
>>> +
>>> +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, count, true, _RET_IP_);
>>> +
>>> +     return __strncpy(dest, src, count);
>>> +}
>>> +EXPORT_SYMBOL(strncpy);
>>> +
>>> +#undef strlcpy
>>> +size_t strlcpy(char *dest, const char *src, size_t size)
>>> +{
>>> +     size_t len = __strlen(src) + 1;
>>> +
>>> +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, min(len, size), true, _RET_IP_);
>>> +
>>> +     return __strlcpy(dest, src, size);
>>> +}
>>> +EXPORT_SYMBOL(strlcpy);
>>> +
>>> +#undef strscpy
>>> +ssize_t strscpy(char *dest, const char *src, size_t count)
>>> +{
>>> +     int len = min(__strlen(src) + 1, count);
>>> +
>>> +     check_memory_region((unsigned long)src, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, len, true, _RET_IP_);
>>> +
>>> +     return __strscpy(dest, src, count);
>>> +}
>>> +EXPORT_SYMBOL(strscpy);
>>> +
>>> +#undef strcat
>>> +char *strcat(char *dest, const char *src)
>>> +{
>>> +     size_t slen = __strlen(src) + 1;
>>> +     size_t dlen = __strlen(dest);
>>> +
>>> +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
>>> +
>>> +     return __strcat(dest, src);
>>> +}
>>> +EXPORT_SYMBOL(strcat);
>>> +
>>> +#undef strncat
>>> +char *strncat(char *dest, const char *src, size_t count)
>>> +{
>>> +     size_t slen = min(__strlen(src) + 1, count);
>>> +     size_t dlen = __strlen(dest);
>>> +
>>> +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
>>> +
>>> +     return __strncat(dest, src, count);
>>> +}
>>> +EXPORT_SYMBOL(strncat);
>>> +
>>> +#undef strlcat
>>> +size_t strlcat(char *dest, const char *src, size_t count)
>>> +{
>>> +     size_t slen = min(__strlen(src) + 1, count);
>>> +     size_t dlen = __strlen(dest);
>>> +
>>> +     check_memory_region((unsigned long)src, slen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
>>> +
>>> +     return __strlcat(dest, src, count);
>>> +}
>>> +EXPORT_SYMBOL(strlcat);
>>> +
>>> +#undef strcmp
>>> +int strcmp(const char *cs, const char *ct)
>>> +{
>>> +     size_t len = min(__strlen(cs) + 1, __strlen(ct) + 1);
>>> +
>>> +     check_memory_region((unsigned long)cs, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)ct, len, false, _RET_IP_);
>>> +
>>> +     return __strcmp(cs, ct);
>>> +}
>>> +EXPORT_SYMBOL(strcmp);
>>> +
>>> +#undef strncmp
>>> +int strncmp(const char *cs, const char *ct, size_t count)
>>> +{
>>> +     size_t len = min3(__strlen(cs) + 1, __strlen(ct) + 1, count);
>>> +
>>> +     check_memory_region((unsigned long)cs, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)ct, len, false, _RET_IP_);
>>> +
>>> +     return __strncmp(cs, ct, count);
>>> +}
>>> +EXPORT_SYMBOL(strncmp);
>>> +
>>> +#undef strcasecmp
>>> +int strcasecmp(const char *s1, const char *s2)
>>> +{
>>> +     size_t len = min(__strlen(s1) + 1, __strlen(s2) + 1);
>>> +
>>> +     check_memory_region((unsigned long)s1, len, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)s2, len, false, _RET_IP_);
>>> +
>>> +     return __strcasecmp(s1, s2);
>>> +}
>>> +EXPORT_SYMBOL(strcasecmp);
>>> +
>>> +#undef strncasecmp
>>> +int strncasecmp(const char *s1, const char *s2, size_t len)
>>> +{
>>> +     size_t sz = min3(__strlen(s1) + 1, __strlen(s2) + 1, len);
>>> +
>>> +     check_memory_region((unsigned long)s1, sz, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)s2, sz, false, _RET_IP_);
>>> +
>>> +     return __strncasecmp(s1, s2, len);
>>> +}
>>> +EXPORT_SYMBOL(strncasecmp);
>>> +
>>> +#undef strchr
>>> +char *strchr(const char *s, int c)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
>>> +
>>> +     return __strchr(s, c);
>>> +}
>>> +EXPORT_SYMBOL(strchr);
>>> +
>>> +#undef strchrnul
>>> +char *strchrnul(const char *s, int c)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
>>> +
>>> +     return __strchrnul(s, c);
>>> +}
>>> +EXPORT_SYMBOL(strchrnul);
>>> +
>>> +#undef strrchr
>>> +char *strrchr(const char *s, int c)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
>>> +
>>> +     return __strrchr(s, c);
>>> +}
>>> +EXPORT_SYMBOL(strrchr);
>>> +
>>> +#undef strnchr
>>> +char *strnchr(const char *s, size_t count, int c)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
>>> +
>>> +     return __strnchr(s, count, c);
>>> +}
>>> +EXPORT_SYMBOL(strnchr);
>>> +
>>> +#undef skip_spaces
>>> +char *skip_spaces(const char *str)
>>> +{
>>> +     size_t len = __strlen(str) + 1;
>>> +
>>> +     check_memory_region((unsigned long)str, len, false, _RET_IP_);
>>> +
>>> +     return __skip_spaces(str);
>>> +}
>>> +EXPORT_SYMBOL(skip_spaces);
>>> +
>>> +#undef strim
>>> +char *strim(char *s)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, false, _RET_IP_);
>>> +
>>> +     return __strim(s);
>>> +}
>>> +EXPORT_SYMBOL(strim);
>>> +
>>> +#undef strstr
>>> +char *strstr(const char *s1, const char *s2)
>>> +{
>>> +     size_t l1 = __strlen(s1) + 1;
>>> +     size_t l2 = __strlen(s2) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
>>> +
>>> +     return __strstr(s1, s2);
>>> +}
>>> +EXPORT_SYMBOL(strstr);
>>> +
>>> +#undef strnstr
>>> +char *strnstr(const char *s1, const char *s2, size_t len)
>>> +{
>>> +     size_t l1 = min(__strlen(s1) + 1, len);
>>> +     size_t l2 = __strlen(s2) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
>>> +
>>> +     return __strnstr(s1, s2, len);
>>> +}
>>> +EXPORT_SYMBOL(strnstr);
>>> +
>>> +#undef strlen
>>> +size_t strlen(const char *s)
>>> +{
>>> +     size_t len = __strlen(s);
>>> +
>>> +     check_memory_region((unsigned long)s, len + 1, false, _RET_IP_);
>>> +
>>> +     return len;
>>> +}
>>> +EXPORT_SYMBOL(strlen);
>>> +
>>> +#undef strnlen
>>> +size_t strnlen(const char *s, size_t count)
>>> +{
>>> +     size_t len = __strnlen(s, count);
>>> +
>>> +     check_memory_region((unsigned long)s, min(len + 1, count), false, _RET_IP_);
>>> +
>>> +     return len;
>>> +}
>>> +EXPORT_SYMBOL(strnlen);
>>> +
>>> +#undef strpbrk
>>> +char *strpbrk(const char *cs, const char *ct)
>>> +{
>>> +     size_t ls = __strlen(cs) + 1;
>>> +     size_t lt = __strlen(ct) + 1;
>>> +
>>> +     check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
>>> +
>>> +     return __strpbrk(cs, ct);
>>> +}
>>> +EXPORT_SYMBOL(strpbrk);
>>> +
>>> +#undef strsep
>>> +char *strsep(char **s, const char *ct)
>>> +{
>>> +     char *cs = *s;
>>> +
>>> +     check_memory_region((unsigned long)s, sizeof(*s), true, _RET_IP_);
>>> +
>>> +     if (cs) {
>>> +             int ls = __strlen(cs) + 1;
>>> +             int lt = __strlen(ct) + 1;
>>> +
>>> +             check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
>>> +             check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
>>> +     }
>>> +
>>> +     return __strsep(s, ct);
>>> +}
>>> +EXPORT_SYMBOL(strsep);
>>> +
>>> +#undef strspn
>>> +size_t strspn(const char *s, const char *accept)
>>> +{
>>> +     size_t ls = __strlen(s) + 1;
>>> +     size_t la = __strlen(accept) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, ls, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)accept, la, false, _RET_IP_);
>>> +
>>> +     return __strspn(s, accept);
>>> +}
>>> +EXPORT_SYMBOL(strspn);
>>> +
>>> +#undef strcspn
>>> +size_t strcspn(const char *s, const char *reject)
>>> +{
>>> +     size_t ls = __strlen(s) + 1;
>>> +     size_t lr = __strlen(reject) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, ls, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)reject, lr, false, _RET_IP_);
>>> +
>>> +     return __strcspn(s, reject);
>>> +}
>>> +EXPORT_SYMBOL(strcspn);
>>> +
>>> +#undef memscan
>>> +void *memscan(void *addr, int c, size_t size)
>>> +{
>>> +     check_memory_region((unsigned long)addr, size, false, _RET_IP_);
>>> +
>>> +     return __memscan(addr, c, size);
>>> +}
>>> +EXPORT_SYMBOL(memscan);
>>> +
>>> +#undef memcmp
>>> +int memcmp(const void *cs, const void *ct, size_t count)
>>> +{
>>> +     check_memory_region((unsigned long)cs, count, false, _RET_IP_);
>>> +     check_memory_region((unsigned long)ct, count, false, _RET_IP_);
>>> +
>>> +     return __memcmp(cs, ct, count);
>>> +}
>>> +EXPORT_SYMBOL(memcmp);
>>> +
>>> +#undef memchr
>>> +void *memchr(const void *s, int c, size_t n)
>>> +{
>>> +     check_memory_region((unsigned long)s, n, false, _RET_IP_);
>>> +
>>> +     return __memchr(s, c, n);
>>> +}
>>> +EXPORT_SYMBOL(memchr);
>>> +
>>> +#undef memchr_inv
>>> +void *memchr_inv(const void *start, int c, size_t bytes)
>>> +{
>>> +     check_memory_region((unsigned long)start, bytes, false, _RET_IP_);
>>> +
>>> +     return __memchr_inv(start, c, bytes);
>>> +}
>>> +EXPORT_SYMBOL(memchr_inv);
>>> +
>>> +#undef strreplace
>>> +char *strreplace(char *s, char old, char new)
>>> +{
>>> +     size_t len = __strlen(s) + 1;
>>> +
>>> +     check_memory_region((unsigned long)s, len, true, _RET_IP_);
>>> +
>>> +     return __strreplace(s, old, new);
>>> +}
>>> +EXPORT_SYMBOL(strreplace);
>>>

Andrey Ryabinin April 2, 2019, 4:14 p.m. UTC | #4

On 4/2/19 12:43 PM, Christophe Leroy wrote:
> Hi Dmitry, Andrey and others,
> 
> Do you have any comments to this series ?
> 

I don't see justification for adding all these non-instrumented functions. We need only some subset of these functions
and only on powerpc so far. Arches that don't use str*() that early simply doesn't need not-instrumented __str*() variant.

Also I don't think that auto-replace str* to __str* for all not instrumented files is a good idea, as this will reduce KASAN coverage.
E.g. we don't instrument slub.c but there is no reason to use non-instrumented __str*() functions there.

And finally, this series make bug reporting slightly worse. E.g. let's look at strcpy():

+char *strcpy(char *dest, const char *src)
+{
+	size_t len = __strlen(src) + 1;
+
+	check_memory_region((unsigned long)src, len, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
+
+	return __strcpy(dest, src);
+}

If src is not-null terminated string we might not see proper out-of-bounds report from KASAN only a crash in __strlen().
Which might make harder to identify where 'src' comes from, where it was allocated and what's the size of allocated area.


> I'd like to know if this approach is ok or if it is better to keep doing as in https://patchwork.ozlabs.org/patch/1055788/
>
I think the patch from link is a better solution to the problem.

Christophe Leroy April 2, 2019, 8:36 p.m. UTC | #5

Le 02/04/2019 à 18:14, Andrey Ryabinin a écrit :
> 
> 
> On 4/2/19 12:43 PM, Christophe Leroy wrote:
>> Hi Dmitry, Andrey and others,
>>
>> Do you have any comments to this series ?
>>
> 
> I don't see justification for adding all these non-instrumented functions. We need only some subset of these functions
> and only on powerpc so far. Arches that don't use str*() that early simply doesn't need not-instrumented __str*() variant.
> 
> Also I don't think that auto-replace str* to __str* for all not instrumented files is a good idea, as this will reduce KASAN coverage.
> E.g. we don't instrument slub.c but there is no reason to use non-instrumented __str*() functions there.

Ok, I didn't see it that way.

In fact I was seeing the opposite and was considering it as an 
opportunity to increase KASAN coverage. E.g.: at the time being things 
like the above (from arch/xtensa/include/asm/string.h) are not covered 
at all I believe:

#define __HAVE_ARCH_STRCPY
static inline char *strcpy(char *__dest, const char *__src)
{
	register char *__xdest = __dest;
	unsigned long __dummy;

	__asm__ __volatile__("1:\n\t"
		"l8ui	%2, %1, 0\n\t"
		"s8i	%2, %0, 0\n\t"
		"addi	%1, %1, 1\n\t"
		"addi	%0, %0, 1\n\t"
		"bnez	%2, 1b\n\t"
		: "=r" (__dest), "=r" (__src), "=&r" (__dummy)
		: "0" (__dest), "1" (__src)
		: "memory");

	return __xdest;
}

In my series, I have deactivated optimised string functions when KASAN 
is selected like arm64 do. See https://patchwork.ozlabs.org/patch/1055780/
But not every arch does that, meaning that some string functions remains 
not instrumented at all.

Also, I was seeing it as a way to reduce impact on performance with 
KASAN. Because instrumenting each byte access of the non-optimised 
string functions is a performance genocide.

> 
> And finally, this series make bug reporting slightly worse. E.g. let's look at strcpy():
> 
> +char *strcpy(char *dest, const char *src)
> +{
> +	size_t len = __strlen(src) + 1;
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> +
> +	return __strcpy(dest, src);
> +}
> 
> If src is not-null terminated string we might not see proper out-of-bounds report from KASAN only a crash in __strlen().
> Which might make harder to identify where 'src' comes from, where it was allocated and what's the size of allocated area.
> 
> 
>> I'd like to know if this approach is ok or if it is better to keep doing as in https://patchwork.ozlabs.org/patch/1055788/
>>
> I think the patch from link is a better solution to the problem.
> 

Ok, I'll stick with it then. Thanks for your feedback

Christophe

Patch

diff --git a/include/linux/string.h b/include/linux/string.h
index 7927b875f80c..3d2aff2ed402 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -19,54 +19,117 @@  extern void *memdup_user_nul(const void __user *, size_t);
  */
 #include <asm/string.h>
 
+#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
+/*
+ * For files that are not instrumented (e.g. mm/slub.c) we
+ * should use not instrumented version of mem* functions.
+ */
+#define memset16	__memset16
+#define memset32	__memset32
+#define memset64	__memset64
+#define memzero_explicit	__memzero_explicit
+#define strcpy		__strcpy
+#define strncpy		__strncpy
+#define strlcpy		__strlcpy
+#define strscpy		__strscpy
+#define strcat		__strcat
+#define strncat		__strncat
+#define strlcat		__strlcat
+#define strcmp		__strcmp
+#define strncmp		__strncmp
+#define strcasecmp	__strcasecmp
+#define strncasecmp	__strncasecmp
+#define strchr		__strchr
+#define strchrnul	__strchrnul
+#define strrchr		__strrchr
+#define strnchr		__strnchr
+#define skip_spaces	__skip_spaces
+#define strim		__strim
+#define strstr		__strstr
+#define strnstr		__strnstr
+#define strlen		__strlen
+#define strnlen		__strnlen
+#define strpbrk		__strpbrk
+#define strsep		__strsep
+#define strspn		__strspn
+#define strcspn		__strcspn
+#define memscan		__memscan
+#define memcmp		__memcmp
+#define memchr		__memchr
+#define memchr_inv	__memchr_inv
+#define strreplace	__strreplace
+
+#ifndef __NO_FORTIFY
+#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
+#endif
+
+#endif
+
 #ifndef __HAVE_ARCH_STRCPY
 extern char * strcpy(char *,const char *);
+char *__strcpy(char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRNCPY
 extern char * strncpy(char *,const char *, __kernel_size_t);
+char *__strncpy(char *, const char *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRLCPY
 size_t strlcpy(char *, const char *, size_t);
+size_t __strlcpy(char *, const char *, size_t);
 #endif
 #ifndef __HAVE_ARCH_STRSCPY
 ssize_t strscpy(char *, const char *, size_t);
+ssize_t __strscpy(char *, const char *, size_t);
 #endif
 #ifndef __HAVE_ARCH_STRCAT
 extern char * strcat(char *, const char *);
+char *__strcat(char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRNCAT
 extern char * strncat(char *, const char *, __kernel_size_t);
+char *__strncat(char *, const char *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRLCAT
 extern size_t strlcat(char *, const char *, __kernel_size_t);
+size_t __strlcat(char *, const char *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRCMP
 extern int strcmp(const char *,const char *);
+int __strcmp(const char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRNCMP
 extern int strncmp(const char *,const char *,__kernel_size_t);
+int __strncmp(const char *, const char *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRCASECMP
 extern int strcasecmp(const char *s1, const char *s2);
+int __strcasecmp(const char *s1, const char *s2);
 #endif
 #ifndef __HAVE_ARCH_STRNCASECMP
 extern int strncasecmp(const char *s1, const char *s2, size_t n);
+int __strncasecmp(const char *s1, const char *s2, size_t n);
 #endif
 #ifndef __HAVE_ARCH_STRCHR
 extern char * strchr(const char *,int);
+char *__strchr(const char *, int);
 #endif
 #ifndef __HAVE_ARCH_STRCHRNUL
 extern char * strchrnul(const char *,int);
+char *__strchrnul(const char *, int);
 #endif
 #ifndef __HAVE_ARCH_STRNCHR
 extern char * strnchr(const char *, size_t, int);
+char *__strnchr(const char *, size_t, int);
 #endif
 #ifndef __HAVE_ARCH_STRRCHR
 extern char * strrchr(const char *,int);
+char *__strrchr(const char *, int);
 #endif
 extern char * __must_check skip_spaces(const char *);
+char * __must_check __skip_spaces(const char *);
 
 extern char *strim(char *);
+char *__strim(char *);
 
 static inline __must_check char *strstrip(char *str)
 {
@@ -75,27 +138,35 @@  static inline __must_check char *strstrip(char *str)
 
 #ifndef __HAVE_ARCH_STRSTR
 extern char * strstr(const char *, const char *);
+char *__strstr(const char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRNSTR
 extern char * strnstr(const char *, const char *, size_t);
+char *__strnstr(const char *, const char *, size_t);
 #endif
 #ifndef __HAVE_ARCH_STRLEN
 extern __kernel_size_t strlen(const char *);
+__kernel_size_t __strlen(const char *);
 #endif
 #ifndef __HAVE_ARCH_STRNLEN
 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
+__kernel_size_t __strnlen(const char *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_STRPBRK
 extern char * strpbrk(const char *,const char *);
+char *__strpbrk(const char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRSEP
 extern char * strsep(char **,const char *);
+char *__strsep(char **, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRSPN
 extern __kernel_size_t strspn(const char *,const char *);
+__kernel_size_t __strspn(const char *, const char *);
 #endif
 #ifndef __HAVE_ARCH_STRCSPN
 extern __kernel_size_t strcspn(const char *,const char *);
+__kernel_size_t __strcspn(const char *, const char *);
 #endif
 
 #ifndef __HAVE_ARCH_MEMSET
@@ -104,14 +175,17 @@  extern void * memset(void *,int,__kernel_size_t);
 
 #ifndef __HAVE_ARCH_MEMSET16
 extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
+void *__memset16(uint16_t *, uint16_t, __kernel_size_t);
 #endif
 
 #ifndef __HAVE_ARCH_MEMSET32
 extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
+void *__memset32(uint32_t *, uint32_t, __kernel_size_t);
 #endif
 
 #ifndef __HAVE_ARCH_MEMSET64
 extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
+void *__memset64(uint64_t *, uint64_t, __kernel_size_t);
 #endif
 
 static inline void *memset_l(unsigned long *p, unsigned long v,
@@ -146,12 +220,15 @@  extern void * memmove(void *,const void *,__kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMSCAN
 extern void * memscan(void *,int,__kernel_size_t);
+void *__memscan(void *, int, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMCMP
 extern int memcmp(const void *,const void *,__kernel_size_t);
+int __memcmp(const void *, const void *, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMCHR
 extern void * memchr(const void *,int,__kernel_size_t);
+void *__memchr(const void *, int, __kernel_size_t);
 #endif
 #ifndef __HAVE_ARCH_MEMCPY_MCSAFE
 static inline __must_check unsigned long memcpy_mcsafe(void *dst,
@@ -168,7 +245,9 @@  static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
 }
 #endif
 void *memchr_inv(const void *s, int c, size_t n);
+void *__memchr_inv(const void *s, int c, size_t n);
 char *strreplace(char *s, char old, char new);
+char *__strreplace(char *s, char old, char new);
 
 extern void kfree_const(const void *x);
 
diff --git a/lib/Makefile b/lib/Makefile
index 30b9b0bfbba9..19d0237f9b9c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -18,6 +18,8 @@  KCOV_INSTRUMENT_list_debug.o := n
 KCOV_INSTRUMENT_debugobjects.o := n
 KCOV_INSTRUMENT_dynamic_debug.o := n
 
+KASAN_SANITIZE_string.o := n
+
 lib-y := ctype.o string.o string_sysfs.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o timerqueue.o xarray.o \
 	 idr.o int_sqrt.o extable.o \
diff --git a/lib/string.c b/lib/string.c
index f3886c5175ac..31a253201bba 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -85,7 +85,9 @@  EXPORT_SYMBOL(strcasecmp);
  * @dest: Where to copy the string to
  * @src: Where to copy the string from
  */
+#ifndef CONFIG_KASAN
 #undef strcpy
+#endif
 char *strcpy(char *dest, const char *src)
 {
 	char *tmp = dest;
@@ -243,7 +245,9 @@  EXPORT_SYMBOL(strscpy);
  * @dest: The string to be appended to
  * @src: The string to append to it
  */
+#ifndef CONFIG_KASAN
 #undef strcat
+#endif
 char *strcat(char *dest, const char *src)
 {
 	char *tmp = dest;
@@ -319,7 +323,9 @@  EXPORT_SYMBOL(strlcat);
  * @cs: One string
  * @ct: Another string
  */
+#ifndef CONFIG_KASAN
 #undef strcmp
+#endif
 int strcmp(const char *cs, const char *ct)
 {
 	unsigned char c1, c2;
@@ -773,7 +779,9 @@  EXPORT_SYMBOL(memmove);
  * @ct: Another area of memory
  * @count: The size of the area.
  */
+#ifndef CONFIG_KASAN
 #undef memcmp
+#endif
 __visible int memcmp(const void *cs, const void *ct, size_t count)
 {
 	const unsigned char *su1, *su2;
diff --git a/mm/kasan/string.c b/mm/kasan/string.c
index 083b967255a2..0db31bbbf643 100644
--- a/mm/kasan/string.c
+++ b/mm/kasan/string.c
@@ -35,6 +35,42 @@  void *memset(void *addr, int c, size_t len)
 	return __memset(addr, c, len);
 }
 
+#undef memset16
+void *memset16(uint16_t *s, uint16_t v, size_t count)
+{
+	check_memory_region((unsigned long)s, count << 1, true, _RET_IP_);
+
+	return __memset16(s, v, count);
+}
+EXPORT_SYMBOL(memset16);
+
+#undef memset32
+void *memset32(uint32_t *s, uint32_t v, size_t count)
+{
+	check_memory_region((unsigned long)s, count << 2, true, _RET_IP_);
+
+	return __memset32(s, v, count);
+}
+EXPORT_SYMBOL(memset32);
+
+#undef memset64
+void *memset64(uint64_t *s, uint64_t v, size_t count)
+{
+	check_memory_region((unsigned long)s, count << 3, true, _RET_IP_);
+
+	return __memset64(s, v, count);
+}
+EXPORT_SYMBOL(memset64);
+
+#undef memzero_explicit
+void memzero_explicit(void *s, size_t count)
+{
+	check_memory_region((unsigned long)s, count, true, _RET_IP_);
+
+	return __memzero_explicit(s, count);
+}
+EXPORT_SYMBOL(memzero_explicit);
+
 #undef memmove
 void *memmove(void *dest, const void *src, size_t len)
 {
@@ -52,3 +88,361 @@  void *memcpy(void *dest, const void *src, size_t len)
 
 	return __memcpy(dest, src, len);
 }
+
+#undef strcpy
+char *strcpy(char *dest, const char *src)
+{
+	size_t len = __strlen(src) + 1;
+
+	check_memory_region((unsigned long)src, len, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
+
+	return __strcpy(dest, src);
+}
+EXPORT_SYMBOL(strcpy);
+
+#undef strncpy
+char *strncpy(char *dest, const char *src, size_t count)
+{
+	size_t len = min(__strlen(src) + 1, count);
+
+	check_memory_region((unsigned long)src, len, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, count, true, _RET_IP_);
+
+	return __strncpy(dest, src, count);
+}
+EXPORT_SYMBOL(strncpy);
+
+#undef strlcpy
+size_t strlcpy(char *dest, const char *src, size_t size)
+{
+	size_t len = __strlen(src) + 1;
+
+	check_memory_region((unsigned long)src, len, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, min(len, size), true, _RET_IP_);
+
+	return __strlcpy(dest, src, size);
+}
+EXPORT_SYMBOL(strlcpy);
+
+#undef strscpy
+ssize_t strscpy(char *dest, const char *src, size_t count)
+{
+	int len = min(__strlen(src) + 1, count);
+
+	check_memory_region((unsigned long)src, len, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
+
+	return __strscpy(dest, src, count);
+}
+EXPORT_SYMBOL(strscpy);
+
+#undef strcat
+char *strcat(char *dest, const char *src)
+{
+	size_t slen = __strlen(src) + 1;
+	size_t dlen = __strlen(dest);
+
+	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
+	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
+
+	return __strcat(dest, src);
+}
+EXPORT_SYMBOL(strcat);
+
+#undef strncat
+char *strncat(char *dest, const char *src, size_t count)
+{
+	size_t slen = min(__strlen(src) + 1, count);
+	size_t dlen = __strlen(dest);
+
+	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
+	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
+
+	return __strncat(dest, src, count);
+}
+EXPORT_SYMBOL(strncat);
+
+#undef strlcat
+size_t strlcat(char *dest, const char *src, size_t count)
+{
+	size_t slen = min(__strlen(src) + 1, count);
+	size_t dlen = __strlen(dest);
+
+	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
+	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
+	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
+
+	return __strlcat(dest, src, count);
+}
+EXPORT_SYMBOL(strlcat);
+
+#undef strcmp
+int strcmp(const char *cs, const char *ct)
+{
+	size_t len = min(__strlen(cs) + 1, __strlen(ct) + 1);
+
+	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
+	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
+
+	return __strcmp(cs, ct);
+}
+EXPORT_SYMBOL(strcmp);
+
+#undef strncmp
+int strncmp(const char *cs, const char *ct, size_t count)
+{
+	size_t len = min3(__strlen(cs) + 1, __strlen(ct) + 1, count);
+
+	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
+	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
+
+	return __strncmp(cs, ct, count);
+}
+EXPORT_SYMBOL(strncmp);
+
+#undef strcasecmp
+int strcasecmp(const char *s1, const char *s2)
+{
+	size_t len = min(__strlen(s1) + 1, __strlen(s2) + 1);
+
+	check_memory_region((unsigned long)s1, len, false, _RET_IP_);
+	check_memory_region((unsigned long)s2, len, false, _RET_IP_);
+
+	return __strcasecmp(s1, s2);
+}
+EXPORT_SYMBOL(strcasecmp);
+
+#undef strncasecmp
+int strncasecmp(const char *s1, const char *s2, size_t len)
+{
+	size_t sz = min3(__strlen(s1) + 1, __strlen(s2) + 1, len);
+
+	check_memory_region((unsigned long)s1, sz, false, _RET_IP_);
+	check_memory_region((unsigned long)s2, sz, false, _RET_IP_);
+
+	return __strncasecmp(s1, s2, len);
+}
+EXPORT_SYMBOL(strncasecmp);
+
+#undef strchr
+char *strchr(const char *s, int c)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, false, _RET_IP_);
+
+	return __strchr(s, c);
+}
+EXPORT_SYMBOL(strchr);
+
+#undef strchrnul
+char *strchrnul(const char *s, int c)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, false, _RET_IP_);
+
+	return __strchrnul(s, c);
+}
+EXPORT_SYMBOL(strchrnul);
+
+#undef strrchr
+char *strrchr(const char *s, int c)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, false, _RET_IP_);
+
+	return __strrchr(s, c);
+}
+EXPORT_SYMBOL(strrchr);
+
+#undef strnchr
+char *strnchr(const char *s, size_t count, int c)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, false, _RET_IP_);
+
+	return __strnchr(s, count, c);
+}
+EXPORT_SYMBOL(strnchr);
+
+#undef skip_spaces
+char *skip_spaces(const char *str)
+{
+	size_t len = __strlen(str) + 1;
+
+	check_memory_region((unsigned long)str, len, false, _RET_IP_);
+
+	return __skip_spaces(str);
+}
+EXPORT_SYMBOL(skip_spaces);
+
+#undef strim
+char *strim(char *s)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, false, _RET_IP_);
+
+	return __strim(s);
+}
+EXPORT_SYMBOL(strim);
+
+#undef strstr
+char *strstr(const char *s1, const char *s2)
+{
+	size_t l1 = __strlen(s1) + 1;
+	size_t l2 = __strlen(s2) + 1;
+
+	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
+	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
+
+	return __strstr(s1, s2);
+}
+EXPORT_SYMBOL(strstr);
+
+#undef strnstr
+char *strnstr(const char *s1, const char *s2, size_t len)
+{
+	size_t l1 = min(__strlen(s1) + 1, len);
+	size_t l2 = __strlen(s2) + 1;
+
+	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
+	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
+
+	return __strnstr(s1, s2, len);
+}
+EXPORT_SYMBOL(strnstr);
+
+#undef strlen
+size_t strlen(const char *s)
+{
+	size_t len = __strlen(s);
+
+	check_memory_region((unsigned long)s, len + 1, false, _RET_IP_);
+
+	return len;
+}
+EXPORT_SYMBOL(strlen);
+
+#undef strnlen
+size_t strnlen(const char *s, size_t count)
+{
+	size_t len = __strnlen(s, count);
+
+	check_memory_region((unsigned long)s, min(len + 1, count), false, _RET_IP_);
+
+	return len;
+}
+EXPORT_SYMBOL(strnlen);
+
+#undef strpbrk
+char *strpbrk(const char *cs, const char *ct)
+{
+	size_t ls = __strlen(cs) + 1;
+	size_t lt = __strlen(ct) + 1;
+
+	check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
+	check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
+
+	return __strpbrk(cs, ct);
+}
+EXPORT_SYMBOL(strpbrk);
+
+#undef strsep
+char *strsep(char **s, const char *ct)
+{
+	char *cs = *s;
+
+	check_memory_region((unsigned long)s, sizeof(*s), true, _RET_IP_);
+
+	if (cs) {
+		int ls = __strlen(cs) + 1;
+		int lt = __strlen(ct) + 1;
+
+		check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
+		check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
+	}
+
+	return __strsep(s, ct);
+}
+EXPORT_SYMBOL(strsep);
+
+#undef strspn
+size_t strspn(const char *s, const char *accept)
+{
+	size_t ls = __strlen(s) + 1;
+	size_t la = __strlen(accept) + 1;
+
+	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
+	check_memory_region((unsigned long)accept, la, false, _RET_IP_);
+
+	return __strspn(s, accept);
+}
+EXPORT_SYMBOL(strspn);
+
+#undef strcspn
+size_t strcspn(const char *s, const char *reject)
+{
+	size_t ls = __strlen(s) + 1;
+	size_t lr = __strlen(reject) + 1;
+
+	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
+	check_memory_region((unsigned long)reject, lr, false, _RET_IP_);
+
+	return __strcspn(s, reject);
+}
+EXPORT_SYMBOL(strcspn);
+
+#undef memscan
+void *memscan(void *addr, int c, size_t size)
+{
+	check_memory_region((unsigned long)addr, size, false, _RET_IP_);
+
+	return __memscan(addr, c, size);
+}
+EXPORT_SYMBOL(memscan);
+
+#undef memcmp
+int memcmp(const void *cs, const void *ct, size_t count)
+{
+	check_memory_region((unsigned long)cs, count, false, _RET_IP_);
+	check_memory_region((unsigned long)ct, count, false, _RET_IP_);
+
+	return __memcmp(cs, ct, count);
+}
+EXPORT_SYMBOL(memcmp);
+
+#undef memchr
+void *memchr(const void *s, int c, size_t n)
+{
+	check_memory_region((unsigned long)s, n, false, _RET_IP_);
+
+	return __memchr(s, c, n);
+}
+EXPORT_SYMBOL(memchr);
+
+#undef memchr_inv
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+	check_memory_region((unsigned long)start, bytes, false, _RET_IP_);
+
+	return __memchr_inv(start, c, bytes);
+}
+EXPORT_SYMBOL(memchr_inv);
+
+#undef strreplace
+char *strreplace(char *s, char old, char new)
+{
+	size_t len = __strlen(s) + 1;
+
+	check_memory_region((unsigned long)s, len, true, _RET_IP_);
+
+	return __strreplace(s, old, new);
+}
+EXPORT_SYMBOL(strreplace);