Linux Virtualization - Nov 2014 - [PATCH v6 25/46] virtio_net: stricter short buffer length checks

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>
Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.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 516f2cb..098f443 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

On Fri, Nov 28, 2014 at 4:09 AM, Michael S. Tsirkin <mst at redhat.com> 
wrote:
> 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>
> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.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 516f2cb..098f443 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
Reviewed-by: Jason Wang <jasowang at redhat.com>