The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 50c0ada627f56c92f5953a8bf9158b045ad026a1 Mon Sep 17 00:00:00 2001 From: Jason Wang jasowang@redhat.com Date: Fri, 17 Jun 2022 15:29:49 +0800 Subject: [PATCH] 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 db05b5e930be..8a5810bcb839 100644 --- 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");