[PATCH AUTOSEL for 4.15 64/78] ip_gre: fix error path when erspan_rcv failed

[Sasha Levin]

From: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>

[ Upstream commit dd8d5b8c5b22e31079b259b8bfb686f1fac1080a ]

When erspan_rcv call return PACKET_REJECT, we shoudn't call ipgre_rcv to
process packets again, instead send icmp unreachable message in error
path.

Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
Acked-by: William Tu <u9012063@xxxxxxxxx>
Cc: William Tu <u9012063@xxxxxxxxx>
Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 net/ipv4/ip_gre.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 45ffd3d045d2..e05bca0e61fc 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -408,11 +408,13 @@ static int gre_rcv(struct sk_buff *skb)
 	if (unlikely(tpi.proto == htons(ETH_P_ERSPAN))) {
 		if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
 			return 0;
+		goto out;
 	}
 
 	if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
 		return 0;
 
+out:
 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 drop:
 	kfree_skb(skb);
-- 
2.14.1