From 9ed9cac1850a2a55674b4a17100c50b46f645921 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 23 Sep 2022 13:28:07 -0700 Subject: slab: Remove __malloc attribute from realloc functions The __malloc attribute should not be applied to "realloc" functions, as the returned pointer may alias the storage of the prior pointer. Instead of splitting __malloc from __alloc_size, which would be a huge amount of churn, just create __realloc_size for the few cases where it is needed. Thanks to Geert Uytterhoeven for reporting build failures with gcc-8 in earlier version which tried to remove the #ifdef. While the "alloc_size" attribute is available on all GCC versions, I forgot that it gets disabled explicitly by the kernel in GCC < 9.1 due to misbehaviors. Add a note to the compiler_attributes.h entry for it. Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrew Morton Cc: Vlastimil Babka Cc: Roman Gushchin Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Marco Elver Cc: linux-mm@kvack.org Signed-off-by: Kees Cook Signed-off-by: Vlastimil Babka --- include/linux/compiler_attributes.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/compiler_attributes.h') diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 445e80517cab..96a4ed11b4be 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -35,7 +35,8 @@ /* * Note: do not use this directly. Instead, use __alloc_size() since it is conditionally - * available and includes other attributes. + * available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined + * in compiler-gcc.h, due to misbehaviors. * * 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 -- cgit