dm: fix potential for q->make_request_fn NULL pointer
authorMike Snitzer <snitzer@redhat.com>
Mon, 27 Jan 2020 19:07:23 +0000 (14:07 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 11 Feb 2020 12:35:27 +0000 (04:35 -0800)
commit78cbd2c397bfca30c1b967fd3c1c65933a3d757e
treeaf79c48bbb4a3598bc3c4fc8e2d3b24bdcfd068c
parent1426201af047f233d98958e1862a13f66e9ce09f
dm: fix potential for q->make_request_fn NULL pointer

commit 47ace7e012b9f7ad71d43ac9063d335ea3d6820b upstream.

Move blk_queue_make_request() to dm.c:alloc_dev() so that
q->make_request_fn is never NULL during the lifetime of a DM device
(even one that is created without a DM table).

Otherwise generic_make_request() will crash simply by doing:
  dmsetup create -n test
  mount /dev/dm-N /mnt

While at it, move ->congested_data initialization out of
dm.c:alloc_dev() and into the bio-based specific init method.

Reported-by: Stefan Bader <stefan.bader@canonical.com>
BugLink: https://bugs.launchpad.net/bugs/1860231
Fixes: ff36ab34583a ("dm: remove request-based logic from make_request_fn wrapper")
Depends-on: c12c9a3c3860c ("dm: various cleanups to md->queue initialization code")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/md/dm.c