--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -84,6 +84,7 @@ static int xfrm6_tunnel_check_size(struc
 		mtu = IPV6_MIN_MTU;
 
 	if (skb->len > mtu) {
+		skb->dev = dst->dev;
 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
 		ret = -EMSGSIZE;
 	}