4.9-stable review patch. If anyone has any objections, please let me know.
------------------
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; }