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 b4c356a..e789a4a 100644 (file)
--- 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);