blk-mq: fix double-free in error path

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.

Cc: <stable@vger.kernel.org>
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index e3387a74a9a2..d53a764b05ea 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -524,6 +524,7 @@ 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) {
                 kfree(bt->map);
+                bt->map = NULL;
                 return -ENOMEM;
         }