diff options
| author | Bart Van Assche <bvanassche@acm.org> | 2014-12-09 16:57:48 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-12-09 09:07:13 -0700 |
| commit | 45a9c9d909b24c6ad0e28a7946e7486e73010319 (patch) | |
| tree | 7317f2beee89119a5e2906dea3c6601e11ae1d61 /block/blk-sysfs.c | |
| parent | 19c66e59ce57e7b181625cbb408d48eb10837763 (diff) | |
| download | lwn-45a9c9d909b24c6ad0e28a7946e7486e73010319.tar.gz lwn-45a9c9d909b24c6ad0e28a7946e7486e73010319.zip | |
blk-mq: Fix a use-after-free
blk-mq users are allowed to free the memory request_queue.tag_set
points at after blk_cleanup_queue() has finished but before
blk_release_queue() has started. This can happen e.g. in the SCSI
core. The SCSI core namely embeds the tag_set structure in a SCSI
host structure. The SCSI host structure is freed by
scsi_host_dev_release(). This function is called after
blk_cleanup_queue() finished but can be called before
blk_release_queue().
This means that it is not safe to access request_queue.tag_set from
inside blk_release_queue(). Hence remove the blk_sync_queue() call
from blk_release_queue(). This call is not necessary - outstanding
requests must have finished before blk_release_queue() is
called. Additionally, move the blk_mq_free_queue() call from
blk_release_queue() to blk_cleanup_queue() to avoid that struct
request_queue.tag_set gets accessed after it has been freed.
This patch avoids that the following kernel oops can be triggered
when deleting a SCSI host for which scsi-mq was enabled:
Call Trace:
[<ffffffff8109a7c4>] lock_acquire+0xc4/0x270
[<ffffffff814ce111>] mutex_lock_nested+0x61/0x380
[<ffffffff812575f0>] blk_mq_free_queue+0x30/0x180
[<ffffffff8124d654>] blk_release_queue+0x84/0xd0
[<ffffffff8126c29b>] kobject_cleanup+0x7b/0x1a0
[<ffffffff8126c140>] kobject_put+0x30/0x70
[<ffffffff81245895>] blk_put_queue+0x15/0x20
[<ffffffff8125c409>] disk_release+0x99/0xd0
[<ffffffff8133d056>] device_release+0x36/0xb0
[<ffffffff8126c29b>] kobject_cleanup+0x7b/0x1a0
[<ffffffff8126c140>] kobject_put+0x30/0x70
[<ffffffff8125a78a>] put_disk+0x1a/0x20
[<ffffffff811d4cb5>] __blkdev_put+0x135/0x1b0
[<ffffffff811d56a0>] blkdev_put+0x50/0x160
[<ffffffff81199eb4>] kill_block_super+0x44/0x70
[<ffffffff8119a2a4>] deactivate_locked_super+0x44/0x60
[<ffffffff8119a87e>] deactivate_super+0x4e/0x70
[<ffffffff811b9833>] cleanup_mnt+0x43/0x90
[<ffffffff811b98d2>] __cleanup_mnt+0x12/0x20
[<ffffffff8107252c>] task_work_run+0xac/0xe0
[<ffffffff81002c01>] do_notify_resume+0x61/0xa0
[<ffffffff814d2c58>] int_signal+0x12/0x17
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robert Elliott <elliott@hp.com>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Cc: <stable@vger.kernel.org> # v3.13+
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-sysfs.c')
| -rw-r--r-- | block/blk-sysfs.c | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 1fac43408911..935ea2aa0730 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -492,17 +492,15 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head) * Currently, its primary task it to free all the &struct request * structures that were allocated to the queue and the queue itself. * - * Caveat: - * Hopefully the low level driver will have finished any - * outstanding requests first... + * Note: + * The low level driver must have finished any outstanding requests first + * via blk_cleanup_queue(). **/ static void blk_release_queue(struct kobject *kobj) { struct request_queue *q = container_of(kobj, struct request_queue, kobj); - blk_sync_queue(q); - blkcg_exit_queue(q); if (q->elevator) { @@ -517,9 +515,7 @@ static void blk_release_queue(struct kobject *kobj) if (q->queue_tags) __blk_queue_free_tags(q); - if (q->mq_ops) - blk_mq_free_queue(q); - else + if (!q->mq_ops) blk_free_flush_queue(q->fq); blk_trace_shutdown(q); |