[PATCH net] virtio-net: serialize tx routine during reset

[PATCH net] virtio-net: serialize tx routine during reset

[Jason Wang]

We don't hold any tx lock when trying to disable TX during reset, this
would lead a use after free since ndo_start_xmit() tries to access
the virtqueue which has already been freed. Fix this by using
netif_tx_disable() before freeing the vqs, this could make sure no tx
after vq freeing.

Reported-by: Jean-Philippe Menil <jpmenil@gmail.com>
Tested-by: Jean-Philippe Menil <jpmenil@gmail.com>
Fixes commit f600b6905015 ("virtio_net: Add XDP support")
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/virtio_net.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index a871f45..143d8a9 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1797,6 +1797,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
 	flush_work(&vi->config_work);
 
 	netif_device_detach(vi->dev);
+	netif_tx_disable(vi->dev);
 	cancel_delayed_work_sync(&vi->refill);
 
 	if (netif_running(vi->dev)) {
-- 
2.7.4

Re: [PATCH net] virtio-net: serialize tx routine during reset

[Michael S. Tsirkin]

On Wed, Jun 28, 2017 at 09:51:03AM +0800, Jason Wang wrote:
> We don't hold any tx lock when trying to disable TX during reset, this
> would lead a use after free since ndo_start_xmit() tries to access
> the virtqueue which has already been freed. Fix this by using
> netif_tx_disable() before freeing the vqs, this could make sure no tx
> after vq freeing.
> 
> Reported-by: Jean-Philippe Menil <jpmenil@gmail.com>
> Tested-by: Jean-Philippe Menil <jpmenil@gmail.com>
> Fixes commit f600b6905015 ("virtio_net: Add XDP support")
> Cc: John Fastabend <john.fastabend@gmail.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

Thanks a lot Jason. I think this is needed in stable as well.

> ---
>  drivers/net/virtio_net.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index a871f45..143d8a9 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1797,6 +1797,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
>  	flush_work(&vi->config_work);
>  
>  	netif_device_detach(vi->dev);
> +	netif_tx_disable(vi->dev);
>  	cancel_delayed_work_sync(&vi->refill);
>  
>  	if (netif_running(vi->dev)) {
> -- 
> 2.7.4

Re: [PATCH net] virtio-net: serialize tx routine during reset

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Wed, 28 Jun 2017 09:51:03 +0800

> We don't hold any tx lock when trying to disable TX during reset, this
> would lead a use after free since ndo_start_xmit() tries to access
> the virtqueue which has already been freed. Fix this by using
> netif_tx_disable() before freeing the vqs, this could make sure no tx
> after vq freeing.
> 
> Reported-by: Jean-Philippe Menil <jpmenil@gmail.com>
> Tested-by: Jean-Philippe Menil <jpmenil@gmail.com>
> Fixes commit f600b6905015 ("virtio_net: Add XDP support")
> Cc: John Fastabend <john.fastabend@gmail.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied and queued up for -stable.