From 11e4f1f6a3ea6ed6284732b50f621974c5766f22 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 3 Nov 2014 14:01:25 +0800 Subject: [PATCH] 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 Cheers, Signed-off-by: David S. Miller Signed-off-by: Zefan Li --- drivers/net/macvtap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index f5b9de48bb825..f0e37643045e5 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -634,6 +634,8 @@ 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; -- 2.47.2