* [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready()
@ 2022-06-27 6:36 Jason Wang
2022-06-27 7:44 ` Michael S. Tsirkin
0 siblings, 1 reply; 3+ messages in thread
From: Jason Wang @ 2022-06-27 6:36 UTC (permalink / raw)
To: mst, jasowang, davem, kuba, virtualization, netdev, linux-kernel
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(-)
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
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready()
2022-06-27 6:36 [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready() Jason Wang
@ 2022-06-27 7:44 ` Michael S. Tsirkin
2022-06-27 8:17 ` Jason Wang
0 siblings, 1 reply; 3+ messages in thread
From: Michael S. Tsirkin @ 2022-06-27 7:44 UTC (permalink / raw)
To: Jason Wang; +Cc: kuba, netdev, davem, linux-kernel, 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>
> ---
> 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
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready()
2022-06-27 7:44 ` Michael S. Tsirkin
@ 2022-06-27 8:17 ` Jason Wang
0 siblings, 0 replies; 3+ messages in thread
From: Jason Wang @ 2022-06-27 8:17 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: Jakub Kicinski, netdev, davem, linux-kernel, virtualization
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
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-06-27 8:18 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-06-27 6:36 [PATCH net] virtio-net: fix race between ndo_open() and virtio_device_ready() Jason Wang
2022-06-27 7:44 ` Michael S. Tsirkin
2022-06-27 8:17 ` Jason Wang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).