regression caused by 1d2024f61ec14bdb0c57a97a3fe73685abc2d198?

["Michael S. Tsirkin" <mst@redhat.com>]

It seems that starting with kernel 3.3 ixgbe sets gso_size for
incoming frames. It seems that this might result in gso_size
being set even when gso_type is 0.
This in turn leads to a crash at macvtap_skb_to_vnet_hdr
drivers/net/macvtap.c:628
which has this code:

       if (skb_is_gso(skb)) {
                struct skb_shared_info *sinfo = skb_shinfo(skb);

                /* This is a hint as to how much should be linear. */
                vnet_hdr->hdr_len = skb_headlen(skb);
                vnet_hdr->gso_size = sinfo->gso_size;
                if (sinfo->gso_type & SKB_GSO_TCPV4)
                        vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                else if (sinfo->gso_type & SKB_GSO_TCPV6)
                        vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
                else if (sinfo->gso_type & SKB_GSO_UDP)
                        vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
                else
                        BUG();
                if (sinfo->gso_type & SKB_GSO_TCP_ECN)
                        vnet_hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
        } else
                vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;


Since skb_is_gso tests gso_size.

What's the right way to handle this? Should skb_is_gso be
changed to test gso_type != 0?

-- 
MST