From: Josef Bacik jbacik@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: stable@vger.kernel.org Signed-off-by: Josef Bacik jbacik@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);