queue-4.19/dm-delay-fix-a-crash-when-invalid-device-is-specified.patch

   1 From 81bc6d150ace6250503b825d9d0c10f7bbd24095 Mon Sep 17 00:00:00 2001
   2 From: Mikulas Patocka <mpatocka@redhat.com>
   3 Date: Thu, 25 Apr 2019 12:07:54 -0400
   4 Subject: dm delay: fix a crash when invalid device is specified
   5
   6 From: Mikulas Patocka <mpatocka@redhat.com>
   7
   8 commit 81bc6d150ace6250503b825d9d0c10f7bbd24095 upstream.
   9
  10 When the target line contains an invalid device, delay_ctr() will call
  11 delay_dtr() with NULL workqueue.  Attempting to destroy the NULL
  12 workqueue causes a crash.
  13
  14 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
  15 Cc: stable@vger.kernel.org
  16 Signed-off-by: Mike Snitzer <snitzer@redhat.com>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18
  19 ---
  20  drivers/md/dm-delay.c |    3 ++-
  21  1 file changed, 2 insertions(+), 1 deletion(-)
  22
  23 --- a/drivers/md/dm-delay.c
  24 +++ b/drivers/md/dm-delay.c
  25 @@ -121,7 +121,8 @@ static void delay_dtr(struct dm_target *
  26  {
  27         struct delay_c *dc = ti->private;
  28
  29 -       destroy_workqueue(dc->kdelayd_wq);
  30 +       if (dc->kdelayd_wq)
  31 +               destroy_workqueue(dc->kdelayd_wq);
  32
  33         if (dc->read.dev)
  34                 dm_put_device(ti, dc->read.dev);