The reason is that the conntrack template is set to confirmed before adding
the extension and it is invalid to add extensions to already confirmed
conntracks. Fix by adding the extensions before setting the conntrack to
confirmed.
Reported-by: Jesper Dangaard Brouer <jesper.brouer@gmail.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>