| Message ID | 20220627063656.52397-1-jasowang@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] virtio-net: fix race between ndo_open() and virtio_device_ready() | expand |
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> > --- > 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
On Mon, Jun 27, 2022 at 3:44 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > 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. Yes, but I couldn't find a better commit. > But OK I guess. > > > Signed-off-by: Jason Wang <jasowang@redhat.com> > > With commit log changes: Will post a new version with the above fixed. Thanks > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > > > --- > > 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 >
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");
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> --- drivers/net/virtio_net.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)