[PATCH net] erspan: fix invalid erspan version.

[William Tu <u9012063@gmail.com>]

ERSPAN only support version 1 and 2.  When packets send to an
erspan device which does not have proper version number set,
drop the packet.  In real case, we observe multicast packets
sent to the erspan pernet device, erspan0, which does not have
erspan version configured.

Reported-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: William Tu <u9012063@gmail.com>
---
 net/ipv4/ip_gre.c  | 4 +++-
 net/ipv6/ip6_gre.c | 5 ++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 2409e648454d..2d8efeecf619 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -734,10 +734,12 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
 		erspan_build_header(skb, ntohl(tunnel->parms.o_key),
 				    tunnel->index,
 				    truncate, true);
-	else
+	else if (tunnel->erspan_ver == 2)
 		erspan_build_header_v2(skb, ntohl(tunnel->parms.o_key),
 				       tunnel->dir, tunnel->hwid,
 				       truncate, true);
+	else
+		goto free_skb;
 
 	tunnel->parms.o_flags &= ~TUNNEL_KEY;
 	__gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_ERSPAN));
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index bede77f24784..d20072fc38cb 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -991,11 +991,14 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 			erspan_build_header(skb, ntohl(t->parms.o_key),
 					    t->parms.index,
 					    truncate, false);
-		else
+		else if (t->parms.erspan_ver == 2)
 			erspan_build_header_v2(skb, ntohl(t->parms.o_key),
 					       t->parms.dir,
 					       t->parms.hwid,
 					       truncate, false);
+		else
+			goto tx_err;
+
 		fl6.daddr = t->parms.raddr;
 	}
 
-- 
2.7.4