virtio-net: fix race between ndo_open() and virtio_device_ready()

commit 50c0ada627f56c92f5953a8bf9158b045ad026a1 upstream.

We currently call virtio_device_ready() after netdev
registration. Since ndo_open() can be called immediately
after register_netdev, this means there exists a race between
ndo_open() and virtio_device_ready(): the driver may start to use the
device before DRIVER_OK which violates the spec.

Fix this by switching to use register_netdevice() and protect the
virtio_device_ready() with rtnl_lock() to make sure ndo_open() can
only be called after virtio_device_ready().

Fixes: 4baf1e33d0842 ("virtio_net: enable VQs early")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220617072949.30734-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 468d0ff..318c681 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3241,14 +3241,20 @@ static int virtnet_probe(struct virtio_device *vdev)
                }
        }
 
-       err = register_netdev(dev);
+       /* serialize netdev register + virtio_device_ready() with ndo_open() */
+       rtnl_lock();
+
+       err = register_netdevice(dev);
        if (err) {
                pr_debug("virtio_net: registering device failed\n");
+               rtnl_unlock();
                goto free_failover;
        }
 
        virtio_device_ready(vdev);
 
+       rtnl_unlock();
+
        err = virtnet_cpu_notif_add(vi);
        if (err) {
                pr_debug("virtio_net: registering cpu notifier failed\n");