From: Herbert Xu Date: Mon, 3 Nov 2014 06:01:25 +0000 (+0800) Subject: macvtap: Fix csum_start when VLAN tags are present X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b3101caa21f0bbfe600118d157e039610effd711;p=karo-tx-linux.git macvtap: Fix csum_start when VLAN tags are present commit 3ce9b20f1971690b8b3b620e735ec99431573b39 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: f09e2249c4f5 ("macvtap: restore vlan header on user read") Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman Signed-off-by: David S. Miller --- diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 9b5481c70b4c..07c942b6ae01 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -629,6 +629,8 @@ static void 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;