Patch "vhost: correctly remove wait queue during poll failure" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

vhost: correctly remove wait queue during poll failure

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
vhost-correctly-remove-wait-queue-during-poll-failure.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jason Wang <[email protected]>
Date: Tue, 27 Mar 2018 20:50:52 +0800
Subject: vhost: correctly remove wait queue during poll failure

From: Jason Wang <[email protected]>

[ Upstream commit dc6455a71c7fc5117977e197f67f71b49f27baba ]

We tried to remove vq poll from wait queue, but do not check whether or not it was in a list before. This will lead double free. Fixing this by switching to use vhost_poll_stop() which zeros poll->wqh after removing poll from waitqueue to make sure it won't be freed twice.

---
 drivers/vhost/vhost.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -211,8 +211,7 @@ int vhost_poll_start(struct vhost_poll *
 	if (mask)
 		vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
 	if (mask & POLLERR) {
-		if (poll->wqh)
-			remove_wait_queue(poll->wqh, &poll->wait);
+		vhost_poll_stop(poll);
 		ret = -EINVAL;
 	}
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/skbuff-return-emsgsize-in-skb_to_sgvec-to-prevent-overflow.patch queue-4.9/virtio_net-check-return-value-of-skb_to_sgvec-always.patch queue-4.9/vhost-validate-log-when-iotlb-is-enabled.patch queue-4.9/vhost_net-add-missing-lock-nesting-notation.patch queue-4.9/vhost-correctly-remove-wait-queue-during-poll-failure.patch queue-4.9/virtio_net-check-return-value-of-skb_to_sgvec-in-one-more-location.patch