4.17-stable review patch. If anyone has any objections, please let me know.
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From: Josef Bacik jbacik@fb.com
commit 8364da4751cf22201d74933d5e634176f44ed407 upstream.
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 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/nbd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -173,9 +173,12 @@ static const struct device_attribute pid 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);