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

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>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index db05b5e930bedadd1da9d83aa10f13903185e34b..8a5810bcb839aa0161befa071408886af9851f53 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3655,14 +3655,20 @@ static int virtnet_probe(struct virtio_device *vdev)
        if (vi->has_rss || vi->has_rss_hash_report)
                virtnet_init_default_rss(vi);
 
-       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");