Linux Virtualization - Jan 2018 - [PATCH net] vhost_net: stop device during reset owner

We don't stop device before reset owner, this means we could try to
serve any virtqueue kick before reset dev->worker. This will result a
warn since the work was pending at llist during owner resetting. Fix
this by stopping device during owner reset.

Reported-by: syzbot+eb17c6162478cc50632c at syzkaller.appspotmail.com
Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server")
Signed-off-by: Jason Wang <jasowang at redhat.com>
---
 drivers/vhost/net.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index c7bdeb6..5636c7c 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1208,6 +1208,7 @@ static long vhost_net_reset_owner(struct vhost_net *n)
 	}
 	vhost_net_stop(n, &tx_sock, &rx_sock);
 	vhost_net_flush(n);
+	vhost_dev_stop(&n->dev);
 	vhost_dev_reset_owner(&n->dev, umem);
 	vhost_net_vq_reset(n);
 done:
-- 
2.7.4

From: Jason Wang <jasowang at redhat.com>
Date: Thu, 25 Jan 2018 22:03:52 +0800
> We don't stop device before reset owner, this means we could try to
> serve any virtqueue kick before reset dev->worker. This will result a
> warn since the work was pending at llist during owner resetting. Fix
> this by stopping device during owner reset.
> 
> Reported-by: syzbot+eb17c6162478cc50632c at syzkaller.appspotmail.com
> Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server")
> Signed-off-by: Jason Wang <jasowang at redhat.com>
Applied and queued up for -stable.