From: Mikulas Patocka <mpatocka@redhat.com>
Date: Thu, 25 Apr 2019 16:07:54 +0000 (-0400)
Subject: dm delay: fix a crash when invalid device is specified
X-Git-Tag: v4.4.181~181
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=daea41651d4346a79ceb05312a8ee40fd2318f70;p=thirdparty%2Fkernel%2Fstable.git

dm delay: fix a crash when invalid device is specified

commit 81bc6d150ace6250503b825d9d0c10f7bbd24095 upstream.

When the target line contains an invalid device, delay_ctr() will call
delay_dtr() with NULL workqueue.  Attempting to destroy the NULL
workqueue causes a crash.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index b4c356a211230..e789a4aae4e7f 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -222,7 +222,8 @@ static void delay_dtr(struct dm_target *ti)
 {
 	struct delay_c *dc = ti->private;
 
-	destroy_workqueue(dc->kdelayd_wq);
+	if (dc->kdelayd_wq)
+		destroy_workqueue(dc->kdelayd_wq);
 
 	dm_put_device(ti, dc->dev_read);