Re: [PATCH] virtio-net: fix race between ndo_open() and virtio_device_ready()
From: Jason Wang <jasowang@redhat.com>
Date: 2022-06-27 06:33:28
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lkml, virtualization
On Fri, Jun 17, 2022 at 3:29 PM Jason Wang [off-list ref] wrote:
We used to call virtio_device_ready() after netdev registration. This
cause 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 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>Ok, I think we're fine with this. So I will repost against -net. If we spot issues with unregistering, we can use a separate patch for that. Thanks
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