[PATCH 5.18 025/102] virtio-net: fix race between ndo_open() and virtio_device_ready()

Greg Kroah-Hartman
2022-07-05T12:31:13Z

From: Jason Wang <jasowang@redhat.com>

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>
---
drivers/net/virtio_net.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3641,14 +3641,20 @@ static int virtnet_probe(struct virtio_d
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");