[IPV6]: Fix xfrm tunnel oops with large packets

Signed-off-by: Herbert Xu <[e-mail]>
Acked-by: Hideaki YOSHIFUJI <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv6/xfrm6_output.c

···
 		mtu = IPV6_MIN_MTU;
 
 	if (skb->len > mtu) {
+		skb->dev = dst->dev;
 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
 		ret = -EMSGSIZE;
 	}