linux-kernel - [PATCH] mm/slab.c: check pointer slabp before using it in alloc

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Date:	Sun,  8 Dec 2013 17:38:53 +0800
From:	"ethan.zhao" <ethan.kernel@...il.com>
To:	hristoph@...eter.com, alokk@...softinc.com, shobhit@...softinc.com,
	shai@...lex86.org, cl@...ux.com
Cc:	linux-kernel@...r.kernel.org, "ethan.zhao" <ethan.kernel@...il.com>
Subject: [PATCH] mm/slab.c: check pointer slabp before using it in alloc_slabmgmt()

Move the NULL check of slabp to the right place before refer its memeber in
function alloc_slabmgmt().

This bug may be introduced by rewriting of funcion kmemleak_scan_area(),
the first parameter changed from slabp to &slabp->list.

Signed-off-by: ethan.zhao <ethan.kernel@...il.com>
---
 mm/slab.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 2580db0..b6d27bc 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2612,6 +2612,8 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
 		/* Slab management obj is off-slab. */
 		slabp = kmem_cache_alloc_node(cachep->slabp_cache,
 					      local_flags, nodeid);
+		if (!slabp)
+			return NULL;
 		/*
 		 * If the first object in the slab is leaked (it's allocated
 		 * but no one has a reference to it), we want to make sure
@@ -2620,8 +2622,6 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
 		 */
 		kmemleak_scan_area(&slabp->list, sizeof(struct list_head),
 				   local_flags);
-		if (!slabp)
-			return NULL;
 	} else {
 		slabp = objp + colour_off;
 		colour_off += cachep->slab_size;
-- 
1.8.3.4 (Apple Git-47)

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