[PATCH v3,net-next 1/2] ip_gre: fix error path when erspan_rcv failed

[Haishuang Yan]

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 <u9012...@gmail.com>
Cc: William Tu <u9012...@gmail.com>
Signed-off-by: Haishuang Yan <yanhaishu...@cmss.chinamobile.com>

---
Change since v3:
  * Rebase on latest master branch.
  * Fix wrong commit information.
---
 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 3029e3e..90c9123 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -436,11 +436,13 @@ static int gre_rcv(struct sk_buff *skb)
                     tpi.proto == htons(ETH_P_ERSPAN2))) {
                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);
-- 
1.8.3.1