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mm/slub.c: fix wrong address during slab padding restoration 

Start address calculated for slab padding restoration was wrong.  Wrong
address would point to some section before padding and could cause
corruption

Link: http://lkml.kernel.org/r/1516604578-4577-1-git-send-email-balasubramani_vivekanandan@mentor.com
Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Balasubramani Vivekanandan 2018-01-31 16:15:43 -08:00 committed by Linus Torvalds
parent 84ebb5827d
commit 5d682681f8
1 changed files with 5 additions and 3 deletions
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8
mm/slub.c
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@ -838,6 +838,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
u8 *start;
u8 *fault;
u8 *end;
u8 *pad;
int length;
int remainder;
@ -851,8 +852,9 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
if (!remainder)
return 1;
pad = end - remainder;
metadata_access_enable();
fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
fault = memchr_inv(pad, POISON_INUSE, remainder);
metadata_access_disable();
if (!fault)
return 1;
@ -860,9 +862,9 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
end--;
slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
print_section(KERN_ERR, "Padding ", end - remainder, remainder);
print_section(KERN_ERR, "Padding ", pad, remainder);
restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
return 0;
}