Linux Virtualization - Oct 2014 - [PATCH RFC 4/4] virtio_net: bigger header when VERSION_1 is set

Our buffer length check is not strict enough for mergeable
buffers: buffer can still be shorter that header + address
by 2 bytes.

Fix that up.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 drivers/net/virtio_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index a795a23..9c6d50f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -437,7 +437,7 @@ static void receive_buf(struct virtnet_info *vi, struct
receive_queue *rq,
 	struct sk_buff *skb;
 	struct virtio_net_hdr_mrg_rxbuf *hdr;
 
-	if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
+	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
 		pr_debug("%s: short packet %i\n", dev->name, len);
 		dev->stats.rx_length_errors++;
 		if (vi->mergeable_rx_bufs) {
-- 
MST

With VERSION_1 virtio_net uses same header size
whether mergeable buffers are enabled or not.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 drivers/net/virtio_net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9c6d50f..a2fe340 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1764,7 +1764,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
 		vi->mergeable_rx_bufs = true;
 
-	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
+	    virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
 		vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
 	else
 		vi->hdr_len = sizeof(struct virtio_net_hdr);
-- 
MST

"Michael S. Tsirkin" <mst at redhat.com>
writes:
> With VERSION_1 virtio_net uses same header size
> whether mergeable buffers are enabled or not.
>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
These two are great too, thanks:

Acked-by: Rusty Russell <rusty at rustcorp.com.au>

Cheers,
Rusty.
> ---
>  drivers/net/virtio_net.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 9c6d50f..a2fe340 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1764,7 +1764,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
>  		vi->mergeable_rx_bufs = true;
>  
> -	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
> +	    virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
>  		vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
>  	else
>  		vi->hdr_len = sizeof(struct virtio_net_hdr);
> -- 
> MST