2022-09-22 03:15:40

by Kees Cook

[permalink] [raw]
Subject: [PATCH 12/12] slab: Restore __alloc_size attribute to __kmalloc_track_caller

With skbuff's post-allocation use of ksize() rearranged to use
kmalloc_size_round() prior to allocation, the compiler can correctly
reason about the size of these allocations. The prior mismatch had caused
buffer overflow mitigations to erroneously fire under CONFIG_UBSAN_BOUNDS,
requiring a partial revert of the __alloc_size attributes. Restore the
attribute that had been removed in commit 93dd04ab0b2b ("slab: remove
__alloc_size attribute from __kmalloc_track_caller").

Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
include/linux/slab.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index ac3832b50dbb..dd50ed7207c9 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -693,7 +693,8 @@ static inline __alloc_size(1, 2) void *kcalloc(size_t n, size_t size, gfp_t flag
* allocator where we care about the real place the memory allocation
* request comes from.
-extern void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller);
+extern void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
+ __alloc_size(1);
#define kmalloc_track_caller(size, flags) \
__kmalloc_track_caller(size, flags, _RET_IP_)