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slab: Remove __malloc attribute from realloc functions

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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 <geert@linux-m68k.org> 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 <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: linux-mm@kvack.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Kees Cook
2022-09-23 13:28:07 -07:00
committed by Vlastimil Babka
parent e45cc28872
commit 9ed9cac185
4 changed files with 15 additions and 12 deletions
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12
include/linux/slab.h
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@@ -184,7 +184,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
/*
* Common kmalloc functions provided by all allocators
*/
void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __realloc_size(2);
void kfree(const void *objp);
void kfree_sensitive(const void *objp);
size_t __ksize(const void *objp);
@@ -647,10 +647,10 @@ static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_
* @new_size: new size of a single member of the array
* @flags: the type of memory to allocate (see kmalloc)
*/
static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
size_t new_n,
size_t new_size,
gfp_t flags)
static inline __realloc_size(2, 3) void * __must_check krealloc_array(void *p,
size_t new_n,
size_t new_size,
gfp_t flags)
{
size_t bytes;
@@ -774,7 +774,7 @@ static inline __alloc_size(1, 2) void *kvcalloc(size_t n, size_t size, gfp_t fla
}
extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
__alloc_size(3);
__realloc_size(3);
extern void kvfree(const void *addr);
extern void kvfree_sensitive(const void *addr, size_t len);