[IPV6]: Don't update ADVMSS on routes where the MTU is not also updated

The ADVMSS value was incorrectly updated for ALL routes when the MTU
is updated because it's outside the effect of the if statement's
condition.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 919de682b331..55ea80fac601 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1983,9 +1983,10 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
             !dst_metric_locked(&rt->u.dst, RTAX_MTU) &&
             (dst_mtu(&rt->u.dst) > arg->mtu ||
              (dst_mtu(&rt->u.dst) < arg->mtu &&
-              dst_mtu(&rt->u.dst) == idev->cnf.mtu6)))
+              dst_mtu(&rt->u.dst) == idev->cnf.mtu6))) {
                 rt->u.dst.metrics[RTAX_MTU-1] = arg->mtu;
-        rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(arg->mtu);
+                rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(arg->mtu);
+        }
         return 0;
 }