netdev - [PATCH net-next] ip_gre: check packet length and mtu correctly in erspan_fb

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Date:   Wed,  4 Oct 2017 17:14:05 -0700
From:   William Tu <u9012063@...il.com>
To:     netdev@...r.kernel.org
Cc:     Xin Long <lucien.xin@...il.com>
Subject: [PATCH net-next] ip_gre: check packet length and mtu correctly in erspan_fb_xmit

Similarly to early patch for erspan_xmit(), the ARPHDR_ETHER device
is the length of the whole ether packet.  So skb->len should subtract
the dev->hard_header_len.

Fixes: 1a66a836da63 ("gre: add collect_md mode to ERSPAN tunnel")
Signed-off-by: William Tu <u9012063@...il.com>
Cc: Xin Long <lucien.xin@...il.com>
---
 net/ipv4/ip_gre.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index b279c325c7f6..10b21fe5b3a6 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -579,7 +579,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev,
 	if (gre_handle_offloads(skb, false))
 		goto err_free_rt;
 
-	if (skb->len > dev->mtu) {
+	if (skb->len - dev->hard_header_len > dev->mtu) {
 		pskb_trim(skb, dev->mtu);
 		truncate = true;
 	}
-- 
2.7.4