bridge: Pseudo-header required for the checksum of ICMPv6

Checksum of ICMPv6 is not properly computed because the pseudo header is not used.
Thus, the MLD packet gets dropped by the bridge.
Signed-off-by: NZheng Yan <zheng.z.yan@intel.com>
Reported-by: NAng Way Chuang <wcang@sfc.wide.ad.jp>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -1520,16 +1520,23 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
 		err = pskb_trim_rcsum(skb2, len);
 		if (err)
 			goto out;
+		err = -EINVAL;
 	}
 
+	ip6h = ipv6_hdr(skb2);
+
 	switch (skb2->ip_summed) {
 	case CHECKSUM_COMPLETE:
-		if (!csum_fold(skb2->csum))
+		if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, skb2->len,
+					IPPROTO_ICMPV6, skb2->csum))
 			break;
 		/*FALLTHROUGH*/
 	case CHECKSUM_NONE:
-		skb2->csum = 0;
-		if (skb_checksum_complete(skb2))
+		skb2->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
+							&ip6h->daddr,
+							skb2->len,
+							IPPROTO_ICMPV6, 0));
+		if (__skb_checksum_complete(skb2))
 			goto out;
 	}