[ovs-dev] [PATCH 06/11] ip_gre: check packet length and mtu correctly in erspan tx

Greg Rose gvrose8192 at gmail.com
Wed Apr 25 16:21:44 UTC 2018

From: William Tu <u9012063 at gmail.com>

Upstream commit:
    commit f192970de860d3ab90aa9e2a22853201a57bde78
    Author: William Tu <u9012063 at gmail.com>
    Date:   Thu Oct 5 12:07:12 2017 -0700

    ip_gre: check packet length and mtu correctly in erspan tx

    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")
    Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
    Signed-off-by: William Tu <u9012063 at gmail.com>
    Cc: Xin Long <lucien.xin at gmail.com>
    Cc: David Laight <David.Laight at aculab.com>
    Reviewed-by: Xin Long <lucien.xin at gmail.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>

Cc: William Tu <u9012063 at gmail.com>
Signed-off-by: Greg Rose <gvrose8192 at gmail.com>
 datapath/linux/compat/ip_gre.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/datapath/linux/compat/ip_gre.c b/datapath/linux/compat/ip_gre.c
index 1295fc5..2377d82 100644
--- a/datapath/linux/compat/ip_gre.c
+++ b/datapath/linux/compat/ip_gre.c
@@ -996,8 +996,8 @@ 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) {
-		pskb_trim(skb, dev->mtu);
+	if (skb->len > dev->mtu + dev->hard_header_len) {
+		pskb_trim(skb, dev->mtu + dev->hard_header_len);
 		truncate = true;

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