vti6: fix PMTU caching and reporting on xmit

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>

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index b7f28deddaeaf8aa35f23da3256f10440d84af85..c72ae3a4fe0978b314a0603be59a6668705ce75c 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);