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| author | Junichi Nomura <j-nomura@ce.jp.nec.com> | 2015-05-27 04:22:07 +0000 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-05-27 09:48:51 -0400 |
| commit | 3a1407559a593d4360af12dd2df5296bf8eb0d28 (patch) | |
| tree | e718358079b9e551726503e9a02b90524487ed00 /drivers/md/dm.c | |
| parent | 4ae9944d132b160d444fa3aa875307eb0fa3eeec (diff) | |
| download | linux-3a1407559a593d4360af12dd2df5296bf8eb0d28.tar.bz2 | |
dm: fix NULL pointer when clone_and_map_rq returns !DM_MAPIO_REMAPPED
When stacking request-based DM on blk_mq device, request cloning and
remapping are done in a single call to target's clone_and_map_rq().
The clone is allocated and valid only if clone_and_map_rq() returns
DM_MAPIO_REMAPPED.
The "IS_ERR(clone)" check in map_request() does not cover all the
!DM_MAPIO_REMAPPED cases that are possible (E.g. if underlying devices
are not ready or unavailable, clone_and_map_rq() may return
DM_MAPIO_REQUEUE without ever having established an ERR_PTR). Fix this
by explicitly checking for a return that is not DM_MAPIO_REMAPPED in
map_request().
Without this fix, DM core may call setup_clone() for a NULL clone
and oops like this:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000068
IP: [<ffffffff81227525>] blk_rq_prep_clone+0x7d/0x137
...
CPU: 2 PID: 5793 Comm: kdmwork-253:3 Not tainted 4.0.0-nm #1
...
Call Trace:
[<ffffffffa01d1c09>] map_tio_request+0xa9/0x258 [dm_mod]
[<ffffffff81071de9>] kthread_worker_fn+0xfd/0x150
[<ffffffff81071cec>] ? kthread_parkme+0x24/0x24
[<ffffffff81071cec>] ? kthread_parkme+0x24/0x24
[<ffffffff81071fdd>] kthread+0xe6/0xee
[<ffffffff81093a59>] ? put_lock_stats+0xe/0x20
[<ffffffff81071ef7>] ? __init_kthread_worker+0x5b/0x5b
[<ffffffff814c2d98>] ret_from_fork+0x58/0x90
[<ffffffff81071ef7>] ? __init_kthread_worker+0x5b/0x5b
Fixes: e5863d9ad ("dm: allocate requests in target when stacking on blk-mq devices")
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 4.0+
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 0bf79a0bad37..1c62ed8d09f4 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1972,8 +1972,8 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, dm_kill_unmapped_request(rq, r); return r; } - if (IS_ERR(clone)) - return DM_MAPIO_REQUEUE; + if (r != DM_MAPIO_REMAPPED) + return r; if (setup_clone(clone, rq, tio, GFP_ATOMIC)) { /* -ENOMEM */ ti->type->release_clone_rq(clone); |