This call uses the sock to get the net to lookup the routing
in. With CONFIG_NET_NS this code will OOPS, since the sk ptr
is NULL.

After looking inside the ip6_dst_lookup and drawing the analogy
with respective ipv6 code, it seems, that the dccp ctl socket 
is a good candidate for the first argument.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>