[PATCH 3.16.y-ckt 093/183] blk-mq: fix double-free in error path

Luis Henriques luis.henriques at canonical.com
Fri Mar 6 09:56:24 UTC 2015

3.16.7-ckt8 -stable review patch.  If anyone has any objections, please let me know.


From: Tony Battersby <tonyb at cybernetics.com>

commit 564e559f2baf6a868768d0cac286980b3cfd6e30 upstream.

If the allocation of bt->bs fails, then bt->map can be freed twice, once
in blk_mq_init_bitmap_tags() -> bt_alloc(), and once in
blk_mq_init_bitmap_tags() -> bt_free().  Fix by setting the pointer to
NULL after the first free.

Signed-off-by: Tony Battersby <tonyb at cybernetics.com>
Signed-off-by: Jens Axboe <axboe at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 block/blk-mq-tag.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 1caaa7c4605d..b88f4b375c27 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -511,6 +511,7 @@ static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth,
 	bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL);
 	if (!bt->bs) {
+		bt->map = NULL;
 		return -ENOMEM;

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