From 02f99df1875c11330cd0be69a40fa8ccd14749b2 Mon Sep 17 00:00:00 2001
From: William Tu <u9012063@gmail.com>
Date: Wed, 16 May 2018 17:24:32 -0700
Subject: [PATCH] erspan: fix invalid erspan version.

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 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 9c169bb2444d5..f200b304f76cb 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -722,10 +722,12 @@ 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 69727bc168cb0..a3e1dec96a748 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -979,11 +979,14 @@ 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;
 	}
 
-- 
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