• Bart Van Assche's avatar
    blk-mq: Fix a use-after-free · 45a9c9d9
    Bart Van Assche authored
    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
    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: default avatarBart 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: default avatarJens Axboe <axboe@fb.com>
blk-sysfs.c 15.5 KB