[PATCH 4.14 280/338] dm cache: Fix UAF in destroy()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Luo Meng <luomeng12@huawei.com>

commit 6a459d8edbdbe7b24db42a5a9f21e6aa9e00c2aa upstream.

Dm_cache also has the same UAF problem when dm_resume()
and dm_destroy() are concurrent.

Therefore, cancelling timer again in destroy().

Cc: stable@vger.kernel.org
Fixes: c6b4fcbad044e ("dm: add cache target")
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/md/dm-cache-target.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2034,6 +2034,7 @@ static void destroy(struct cache *cache)
 	if (cache->prison)
 		dm_bio_prison_destroy_v2(cache->prison);
 
+	cancel_delayed_work_sync(&cache->waker);
 	if (cache->wq)
 		destroy_workqueue(cache->wq);