[patch 4/4] change slab poison pattern

[Akinobu Mita]

kref debugging cannot detect kref_put() with unreferenced object,
when the structure including kref is allocated by slab
and slab debugging config is enabled.

Because use-after-free poisoning make kref counter signed value.
So this patch prevents it by changing poisoning pattern.

Signed-off-by: Akinobu Mita <mita@xxxxxxxxxxxxxxxx>
CC: Matt Mackall <mpm@xxxxxxxxxxx>
CC: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
CC: Pekka J Enberg <penberg@xxxxxxxxxxxxxx>

 mm/slab.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

Index: 2.6-git/mm/slab.c
===================================================================
--- 2.6-git.orig/mm/slab.c
+++ 2.6-git/mm/slab.c
@@ -503,9 +503,9 @@ struct kmem_cache {
 #define	RED_ACTIVE	0x170FC2A5UL	/* when obj is active */
 
 /* ...and for poisoning */
-#define	POISON_INUSE	0x5a	/* for use-uninitialised poisoning */
-#define POISON_FREE	0x6b	/* for use-after-free poisoning */
-#define	POISON_END	0xa5	/* end-byte of poisoning */
+#define	POISON_INUSE	0xa5	/* for use-uninitialised poisoning */
+#define POISON_FREE	0xb6	/* for use-after-free poisoning */
+#define	POISON_END	0xab	/* end-byte of poisoning */
 
 /*
  * memory layout of objects:

--
-
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