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: Zheng Yan <zheng.z.yan@intel.com>
Reported-by: Ang Way Chuang <wcang@sfc.wide.ad.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 2d85ca7..22d2d1a 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1520,16 +1520,23 @@
 		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;
 	}