macvtap: Fix csum_start when VLAN tags are present

commit 3ce9b20f19 upstream.

When VLAN is in use in macvtap_put_user, we end up setting
csum_start to the wrong place.  The result is that the whoever
ends up doing the checksum setting will corrupt the packet instead
of writing the checksum to the expected location, usually this
means writing the checksum with an offset of -4.

This patch fixes this by adjusting csum_start when VLAN tags are
detected.

Fixes: f09e2249c4 ("macvtap: restore vlan header on user read")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu
2014-11-03 14:01:25 +08:00
committed by Jiri Slaby
parent 8ad766627e
commit 6e2b9478b3

View File

@@ -625,6 +625,8 @@ static int macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
if (skb->ip_summed == CHECKSUM_PARTIAL) {
vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
vnet_hdr->csum_start = skb_checksum_start_offset(skb);
if (vlan_tx_tag_present(skb))
vnet_hdr->csum_start += VLAN_HLEN;
vnet_hdr->csum_offset = skb->csum_offset;
} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;