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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From foo@baz Wed Apr 11 10:26:56 CEST 2018
From: Jason Wang <jasowang@redhat.com>
Date: Tue, 27 Mar 2018 20:50:52 +0800
Subject: vhost: correctly remove wait queue during poll failure

From: Jason Wang <jasowang@redhat.com>


[ 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.

Cc: Darren Kenny <darren.kenny@oracle.com>
Reported-by: syzbot+c0272972b01b872e604a@syzkaller.appspotmail.com
Fixes: 2b8b328b61c79 ("vhost_net: handle polling errors when setting backend")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/vhost/vhost.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -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 jasowang@redhat.com 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