[PATCH] bridge: mcast snooping, fix IPv6 MLD checksum calculation

["Linus Lüssing" <linus.luessing@web.de>]

In contrast to IGMP, the MLDv1/2 message checksum needs to include an
IPv6 "pseudo-header" in the calculations (see RFC2710, section 3.3;
RFC3810, section 5.1.2).

The multicast snooping feature of the bridge code however did not take
this "pseudo-header" into consideration for the checksum validation when
parsing a snooped IPv6 MLDv1/2 message of another host, leading to
possibly ignored, though valid MLDv1/2 messages. This commit shall fix
this issue.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
 net/bridge/br_multicast.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index f61eb2e..47fae4f 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1525,7 +1525,10 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
 			break;
 		/*FALLTHROUGH*/
 	case CHECKSUM_NONE:
-		skb2->csum = 0;
+		skb2->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
+							  &ip6h->daddr,
+							  skb2->len,
+							  nexthdr, 0));
 		if (skb_checksum_complete(skb2))
 			goto out;
 	}
-- 
1.5.6.5