[PATCH] slub: Fix a crash during slabinfo -v

[PATCH] slub: Fix a crash during slabinfo -v

[Tero Roponen]

Commit f7cb1933621bce66a77f690776a16fe3ebbc4d58 ("SLUB: Pass active
and inactive redzone flags instead of boolean to debug functions")
missed two instances of check_object(). This caused a lot of warnings
during 'slabinfo -v' finally leading to a crash:

  BUG ext4_xattr: Freepointer corrupt
  ...
  BUG buffer_head: Freepointer corrupt
  ...
  BUG ext4_alloc_context: Freepointer corrupt
  ...
  ...
  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: [<ffffffff810a291f>] file_sb_list_del+0x1c/0x35
  PGD 79d78067 PUD 79e67067 PMD 0
  Oops: 0002 [#1] SMP
  last sysfs file: /sys/kernel/slab/:t-0000192/validate

This patch fixes the problem by converting the two missed instances.

Signed-off-by: Tero Roponen <tero.roponen@gmail.com>

diff --git a/mm/slub.c b/mm/slub.c
index 981fb73..bec0e35 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3401,13 +3401,13 @@ static int validate_slab(struct kmem_cache *s, struct page *page,
 
 	for_each_free_object(p, s, page->freelist) {
 		set_bit(slab_index(p, s, addr), map);
-		if (!check_object(s, page, p, 0))
+		if (!check_object(s, page, p, SLUB_RED_INACTIVE))
			return 0;
 	}
 
 	for_each_object(p, s, addr, page->objects)
 		if (!test_bit(slab_index(p, s, addr), map))
-			if (!check_object(s, page, p, 1))
+			if (!check_object(s, page, p, SLUB_RED_ACTIVE))
 				return 0;
 	return 1;
 }

Re: [PATCH] slub: Fix a crash during slabinfo -v

[Christoph Lameter]

On Wed, 1 Dec 2010, Tero Roponen wrote:

> This patch fixes the problem by converting the two missed instances.

Hmmm...A hunk was dropped somewhere.

Acked-by: Christoph Lameter <cl@linux.com>