3.16.7-ckt9 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: Martin KaFai Lau <ka...@fb.com>

commit 3b4711757d7903ab6fa88a9e7ab8901b8227da60 upstream.

ipv6_cow_metrics() currently assumes only DST_HOST routes require
dynamic metrics allocation from inetpeer.  The assumption breaks
when ndisc discovered router with RTAX_MTU and RTAX_HOPLIMIT metric.
Refer to ndisc_router_discovery() in ndisc.c and note that dst_metric_set()
is called after the route is created.

This patch creates the metrics array (by calling dst_cow_metrics_generic) in
ipv6_cow_metrics().

Test:
radvd.conf:
interface qemubr0
{
        AdvLinkMTU 1300;
        AdvCurHopLimit 30;

        prefix fd00:face:face:face::/64
        {
                AdvOnLink on;
                AdvAutonomous on;
                AdvRouterAddr off;
        };
};

Before:
[root@qemu1 ~]# ip -6 r show | egrep -v unreachable
fd00:face:face:face::/64 dev eth0  proto kernel  metric 256  expires 27sec
fe80::/64 dev eth0  proto kernel  metric 256
default via fe80::74df:d0ff:fe23:8ef2 dev eth0  proto ra  metric 1024  expires 
27sec

After:
[root@qemu1 ~]# ip -6 r show | egrep -v unreachable
fd00:face:face:face::/64 dev eth0  proto kernel  metric 256  expires 27sec mtu 
1300
fe80::/64 dev eth0  proto kernel  metric 256  mtu 1300
default via fe80::74df:d0ff:fe23:8ef2 dev eth0  proto ra  metric 1024  expires 
27sec mtu 1300 hoplimit 30

Fixes: 8e2ec639173f325 (ipv6: don't use inetpeer to store metrics for routes.)
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
 net/ipv6/route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 920616d05758..07b1eee067b1 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -141,7 +141,7 @@ static u32 *ipv6_cow_metrics(struct dst_entry *dst, 
unsigned long old)
        u32 *p = NULL;
 
        if (!(rt->dst.flags & DST_HOST))
-               return NULL;
+               return dst_cow_metrics_generic(dst, old);
 
        peer = rt6_get_peer_create(rt);
        if (peer) {
--
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