Message ID | 20210910201132.3809437-1-keescook@chromium.org (mailing list archive) |
---|---|
State | Not Applicable, archived |
Headers | show |
Series | [v2] Compiler Attributes: Check GCC version for __alloc_size attribute | expand |
On 9/10/2021 1:11 PM, Kees Cook wrote: > Unfortunately, just version checking the use of -Wno-alloc-size-larger-than > is not sufficient to make the __alloc_size attribute behave correctly > under older GCC versions. The attribute itself must be disabled in those > situations too, as there appears to be no way to reliably silence the > SIZE_MAX constant expression cases for GCC versions less than 9.1: > > In file included from ./include/linux/resource_ext.h:11, > from ./include/linux/pci.h:40, > from drivers/net/ethernet/intel/ixgbe/ixgbe.h:9, > from drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c:4: > In function 'kmalloc_node', > inlined from 'ixgbe_alloc_q_vector' at ./include/linux/slab.h:743:9: > ./include/linux/slab.h:618:9: error: argument 1 value '18446744073709551615' exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=] > return __kmalloc_node(size, flags, node); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ./include/linux/slab.h: In function 'ixgbe_alloc_q_vector': > ./include/linux/slab.h:455:7: note: in a call to allocation function '__kmalloc_node' declared here > void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_slab_alignment __malloc; > ^~~~~~~~~~~~~~ > > Specifically: > -Wno-alloc-size-larger-than is not correctly handled by GCC < 9.1 > https://godbolt.org/z/hqsfG7q84 (doesn't disable) > https://godbolt.org/z/P9jdrPTYh (doesn't admit to not knowing about option) > https://godbolt.org/z/465TPMWKb (only warns when other warnings appear) > > -Walloc-size-larger-than=18446744073709551615 is not handled by GCC < 8.2 > https://godbolt.org/z/73hh1EPxz (ignores numeric value) > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Miguel Ojeda <ojeda@kernel.org> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Marco Elver <elver@google.com> > Cc: Will Deacon <will@kernel.org> > Cc: Arvind Sankar <nivedita@alum.mit.edu> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: llvm@lists.linux.dev > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> One open-ended comment below. > --- > And now I've added GCC 4.9, 5, and 6 to my build configs... 4.9 is so > old I have to turn off RETPOLIN in defconfig. :P > > v2: > - fix lack of VARARGS in fall-back macro > - add reviewed-by > --- > include/linux/compiler-gcc.h | 9 +++++++++ > include/linux/compiler_attributes.h | 6 ------ > include/linux/compiler_types.h | 5 +++++ > 3 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h > index 01985821944b..3f3efbb651e0 100644 > --- a/include/linux/compiler-gcc.h > +++ b/include/linux/compiler-gcc.h > @@ -151,3 +151,12 @@ > #else > #define __diag_GCC_8(s) > #endif > + > +/* > + * https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute > + * However, prior to 9.1, -Wno-alloc-size-larger-than does not work, > + * making this attribute unusable. > + */ > +#if GCC_VERSION < 90100 > +#define __alloc_size(x, ...) /**/ > +#endif > diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h > index 19f178e20e61..2487be0e7199 100644 > --- a/include/linux/compiler_attributes.h > +++ b/include/linux/compiler_attributes.h > @@ -53,12 +53,6 @@ > #define __aligned(x) __attribute__((__aligned__(x))) > #define __aligned_largest __attribute__((__aligned__)) > > -/* > - * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute > - * clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size It might be nice to keep a link to the clang documentation somewhere as I like the example a little bit more but I guess it does not make sense in compiler_types.h... > - */ > -#define __alloc_size(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) > - > /* > * Note: users of __always_inline currently do not write "inline" themselves, > * which seems to be required by gcc to apply the attribute according > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > index c43308b0a9a9..91de9bead40d 100644 > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -254,6 +254,11 @@ struct ftrace_likely_data { > #define asm_volatile_goto(x...) asm goto(x) > #endif > > +/* If not specifically disabled, allow the use of __alloc_size attribute. */ > +#ifndef __alloc_size > +# define __alloc_size(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) > +#endif > + > #ifdef CONFIG_CC_HAS_ASM_INLINE > #define asm_inline asm __inline > #else >
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 01985821944b..3f3efbb651e0 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -151,3 +151,12 @@ #else #define __diag_GCC_8(s) #endif + +/* + * https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute + * However, prior to 9.1, -Wno-alloc-size-larger-than does not work, + * making this attribute unusable. + */ +#if GCC_VERSION < 90100 +#define __alloc_size(x, ...) /**/ +#endif diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 19f178e20e61..2487be0e7199 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -53,12 +53,6 @@ #define __aligned(x) __attribute__((__aligned__(x))) #define __aligned_largest __attribute__((__aligned__)) -/* - * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute - * clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size - */ -#define __alloc_size(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) - /* * Note: users of __always_inline currently do not write "inline" themselves, * which seems to be required by gcc to apply the attribute according diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index c43308b0a9a9..91de9bead40d 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -254,6 +254,11 @@ struct ftrace_likely_data { #define asm_volatile_goto(x...) asm goto(x) #endif +/* If not specifically disabled, allow the use of __alloc_size attribute. */ +#ifndef __alloc_size +# define __alloc_size(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) +#endif + #ifdef CONFIG_CC_HAS_ASM_INLINE #define asm_inline asm __inline #else