Re: [PATCH 2/2] slab, kmemleak, bugfix, pass the correct pointerto kmemleak_erase()

From: Pekka Enberg
Date: Sun Dec 06 2009 - 03:33:41 EST


Catalin Marinas wrote:
"J. R. Okajima" <hooanon05@xxxxxxxxxxx> wrote:
In ____cache_alloc(), the variable 'ac' may be changed after
cache_alloc_refill() and the following kmemleak_erase() may get an
incorrect pointer.
Update 'ac' after cache_alloc_refill() unconditionally.
cf. http://marc.info/?l=linux-kernel&m=125873373124187&w=2
and its thread.

Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>

Signed-off-by: J. R. Okajima <hooanon05@xxxxxxxxxxx>
---
mm/slab.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 4e61449..66e9047 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3103,6 +3103,11 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
} else {
STATS_INC_ALLOCMISS(cachep);
objp = cache_alloc_refill(cachep, flags);
+ /*
+ * the 'ac' may be updated by cache_alloc_refill(),
+ * and kmemleak_erase() requires its correct value.
+ */
+ ac = cpu_cache_get(cachep);
}
/*
* To avoid a false negative, if an object that is in one of the

Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Thanks.

Applied, thanks!
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/