[PATCH] mm/slub.c: Fix wrong address during slab padding restoration

[Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>]

From: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>

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

Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
---
 mm/slub.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index cfd56e5..733ba32 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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;
 }
 
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>