linux-kernel - [PATCH] bio: Fix potential memory leak in bio_find_or_create

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Date:	Thu,  9 Aug 2012 09:52:12 +0400
From:	Alexey Khoroshilov <khoroshilov@...ras.ru>
To:	Jens Axboe <axboe@...nel.dk>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	ldv-project@...ras.ru
Subject: [PATCH] bio: Fix potential memory leak in bio_find_or_create_slab()

Do not leak memory by updating pointer with potentially NULL realloc return value.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 fs/bio.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/bio.c b/fs/bio.c
index 5eaa70c..3fb4380 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -73,7 +73,7 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
 {
 	unsigned int sz = sizeof(struct bio) + extra_size;
 	struct kmem_cache *slab = NULL;
-	struct bio_slab *bslab;
+	struct bio_slab *bslab, *new_bio_slabs;
 	unsigned int i, entry = -1;
 
 	mutex_lock(&bio_slab_lock);
@@ -97,11 +97,12 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
 
 	if (bio_slab_nr == bio_slab_max && entry == -1) {
 		bio_slab_max <<= 1;
-		bio_slabs = krealloc(bio_slabs,
-				     bio_slab_max * sizeof(struct bio_slab),
-				     GFP_KERNEL);
-		if (!bio_slabs)
+		new_bio_slabs = krealloc(bio_slabs,
+					 bio_slab_max * sizeof(struct bio_slab),
+					 GFP_KERNEL);
+		if (!new_bio_slabs)
 			goto out_unlock;
+		bio_slabs = new_bio_slabs;
 	}
 	if (entry == -1)
 		entry = bio_slab_nr++;
-- 
1.7.9.5

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