[PATCH 2/7] nbd: fix nbd device deletion

[Josef Bacik]

From: Josef Bacik <jba...@fb.com>

This fixes a use after free bug, we shouldn't be doing disk->queue right
after we do del_gendisk(disk).  Save the queue and do the cleanup after
the del_gendisk.

Fixes: c6a4759ea0c9 ("nbd: add device refcounting")
cc: sta...@vger.kernel.org
Signed-off-by: Josef Bacik <jba...@fb.com>
---
 drivers/block/nbd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index afbc202ca6fd..9710a0c338b0 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -173,9 +173,12 @@ static const struct device_attribute pid_attr = {
 static void nbd_dev_remove(struct nbd_device *nbd)
 {
        struct gendisk *disk = nbd->disk;
+       struct request_queue *q;
+
        if (disk) {
+               q = disk->queue;
                del_gendisk(disk);
-               blk_cleanup_queue(disk->queue);
+               blk_cleanup_queue(q);
                blk_mq_free_tag_set(&nbd->tag_set);
                disk->private_data = NULL;
                put_disk(disk);
-- 
2.14.3