diff mbox

macvtap: Fix csum_start when VLAN tags are present

Message ID 20141103060125.GA28295@gondor.apana.org.au
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu Nov. 3, 2014, 6:01 a.m. UTC 
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")
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>


Cheers,

Comments

David Miller Nov. 3, 2014, 7:52 p.m. UTC | #1 
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Mon, 3 Nov 2014 14:01:25 +0800

> 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")
> Cc: stable@vger.kernel.org
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied, thanks Herbert.
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diff mbox

Patch

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index d830e25..d2b8268 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;