vti6: fix PMTU caching and reporting on xmit

[ Upstream commit d6990976af7c5d8f55903bfb4289b6fb030bf754 ]

When setting the skb->dst before doing the MTU check, the route PMTU
caching and reporting is done on the new dst which is about to be
released.

Instead, PMTU handling should be done using the original dst.

This is aligned with IPv4 VTI.

Fixes: ccd740cbc6 ("vti6: Add pmtu handling to vti6_xmit.")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 0e0ab90a433494a259333745be9ef1966022f614..b9e638cc955faa0b11127d9570a0de20c623b67e 100644 (file)
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -480,10 +480,6 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
                goto tx_err_dst_release;
        }
 
-       skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
-       skb_dst_set(skb, dst);
-       skb->dev = skb_dst(skb)->dev;
-
        mtu = dst_mtu(dst);
        if (!skb->ignore_df && skb->len > mtu) {
                skb_dst_update_pmtu(skb, mtu);
@@ -498,9 +494,14 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
                                  htonl(mtu));
                }
 
-               return -EMSGSIZE;
+               err = -EMSGSIZE;
+               goto tx_err_dst_release;
        }
 
+       skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
+       skb_dst_set(skb, dst);
+       skb->dev = skb_dst(skb)->dev;
+
        err = dst_output(t->net, skb->sk, skb);
        if (net_xmit_eval(err) == 0) {
                struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);