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[2/7] nbd: fix nbd device deletion

Message ID 20180516185122.18590-2-josef@toxicpanda.com (mailing list archive)
State New, archived
Headers show

Commit Message

Josef Bacik May 16, 2018, 6:51 p.m. UTC 
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(-)
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Patch

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);