Re: [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready()
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2022-06-27 07:44:35
Also in:
lkml, virtualization
On Mon, Jun 27, 2022 at 02:36:56PM +0800, Jason Wang wrote:
We used to call virtio_device_ready() after netdev registration.
s/used to call/currently call/
This cause
s/This cause/Since ndo_open can be called immediately after register_netdev, this means there exists/
a race between ndo_open() and virtio_device_ready(): if ndo_open() is called before virtio_device_ready(), the driver may start to use the device before DRIVER_OK which violates the spec. Fixing
s/Fixing/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")it's an unusual use of Fixes - the patch in question does not introduce the problem, it just does not fix it completely. But OK I guess.
Signed-off-by: Jason Wang <jasowang@redhat.com>
With commit log changes: Acked-by: Michael S. Tsirkin <mst@redhat.com>
quoted hunk ↗ jump to hunk
--- drivers/net/virtio_net.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)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");-- 2.25.1