ip_tunnel: Fix route fl4 init in ip_md_tunnel_xmit

Init the gre_key from tuninfo->key.tun_id and init the mark
from the skb->mark, set the oif to zero in the collect metadata
mode.

Fixes: cfc7381b ("ip_tunnel: add collect_md mode to IPIP tunnel")
Signed-off-by: Nwenxu <wenxu@ucloud.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ip_tunnel.c

@@ -582,8 +582,9 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		else if (skb->protocol == htons(ETH_P_IPV6))
 			tos = ipv6_get_dsfield((const struct ipv6hdr *)inner_iph);
 	}
-	ip_tunnel_init_flow(&fl4, proto, key->u.ipv4.dst, key->u.ipv4.src, 0,
-			    RT_TOS(tos), tunnel->parms.link, tunnel->fwmark);
+	ip_tunnel_init_flow(&fl4, proto, key->u.ipv4.dst, key->u.ipv4.src,
+			    tunnel_id_to_key32(key->tun_id), RT_TOS(tos),
+			    0, skb->mark);
 	if (tunnel->encap.type != TUNNEL_ENCAP_NONE)
 		goto tx_error;