| Message ID | 20221101223321.1326815-4-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | slab: Provide full coverage for __alloc_size attribute | expand |
On 01/11/2022 23.33, Kees Cook wrote: > Add __realloc_size() hint to kmemdup() so the compiler can reason about > the length of the returned buffer. (These must not use __alloc_size, > since those include __malloc which says the contents aren't defined[1]). > > [1] https://lore.kernel.org/linux-hardening/d199c2af-06af-8a50-a6a1-00eefa0b67b4@prevas.dk/ > > extern char *kstrndup(const char *s, size_t len, gfp_t gfp); > -extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __alloc_size(2); > +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); What tree is this based on? I see that kmemdup() has grown that bogus __alloc_size in next-20221101, but in next-20221102 this commit seems to DTRT, namely -extern void *kmemdup(const void *src, size_t len, gfp_t gfp); +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); (i.e. there should never be an intermediate commit where kmemdup has __alloc_size()). Rasmus
On Wed, Nov 02, 2022 at 10:26:40AM +0100, Rasmus Villemoes wrote: > On 01/11/2022 23.33, Kees Cook wrote: > > Add __realloc_size() hint to kmemdup() so the compiler can reason about > > the length of the returned buffer. (These must not use __alloc_size, > > since those include __malloc which says the contents aren't defined[1]). > > > > [1] https://lore.kernel.org/linux-hardening/d199c2af-06af-8a50-a6a1-00eefa0b67b4@prevas.dk/ > > > > > extern char *kstrndup(const char *s, size_t len, gfp_t gfp); > > -extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __alloc_size(2); > > +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); > > What tree is this based on? I see that kmemdup() has grown that bogus > __alloc_size in next-20221101, but in next-20221102 this commit seems to > DTRT, namely > > -extern void *kmemdup(const void *src, size_t len, gfp_t gfp); > +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) > __realloc_size(2); > > (i.e. there should never be an intermediate commit where kmemdup has > __alloc_size()). Right -- I fixed in in my -next tree to not use __alloc_size.
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index 9e2d96993c30..aa31f54f8b57 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -670,7 +670,7 @@ __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) } extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup) - __alloc_size(2); + __realloc_size(2); __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) { size_t p_size = __struct_size(p); diff --git a/include/linux/string.h b/include/linux/string.h index af1d69e5610e..db28802ab0a6 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -176,7 +176,7 @@ extern void kfree_const(const void *x); extern char *kstrdup(const char *s, gfp_t gfp) __malloc; extern const char *kstrdup_const(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); -extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __alloc_size(2); +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp); extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
Add __realloc_size() hint to kmemdup() so the compiler can reason about the length of the returned buffer. (These must not use __alloc_size, since those include __malloc which says the contents aren't defined[1]). [1] https://lore.kernel.org/linux-hardening/d199c2af-06af-8a50-a6a1-00eefa0b67b4@prevas.dk/ Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Andy Shevchenko <andriy.shevchenko@intel.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/fortify-string.h | 2 +- include/linux/string.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)