From e41c7c68ea771683cae5a7f81c268f38d7912ecb Mon Sep 17 00:00:00 2001
From: William Tu <u9012063@gmail.com>
Date: Fri, 9 Mar 2018 07:34:42 -0800
Subject: [PATCH] ip6erspan: make sure enough headroom at xmit.

The patch adds skb_cow_header() to ensure enough headroom
at ip6erspan_tunnel_xmit before pushing the erspan header
to the skb.

Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv6/ip6_gre.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index a299f5424e16..1bbd0930063e 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -903,6 +903,9 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 		truncate = true;
 	}
 
+	if (skb_cow_head(skb, dev->needed_headroom))
+		goto tx_err;
+
 	t->parms.o_flags &= ~TUNNEL_KEY;
 	IPCB(skb)->flags = 0;