From 5513d08d29511c263c00933c00dd7a82fffda3c9 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 1 Oct 2017 22:00:54 +0800 Subject: [PATCH] ip_gre: check packet length and mtu correctly in erspan_xmit As a ARPHRD_ETHER device, skb->len in erspan_xmit is the length of the whole ether packet. So before checking if a packet size exceeds the mtu, skb->len should subtract dev->hard_header_len. Otherwise, all packets with max size according to mtu would be trimmed to be truncated packet. Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN") Signed-off-by: Xin Long Signed-off-by: David S. Miller --- 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 b25b1e5112d0..2a4ef9dc48ff 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -731,7 +731,7 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb, if (skb_cow_head(skb, dev->needed_headroom)) goto free_skb; - if (skb->len > dev->mtu) { + if (skb->len - dev->hard_header_len > dev->mtu) { pskb_trim(skb, dev->mtu); truncate = true; } -- 2.34.1