On Tue, Sep 26, 2017 at 02:42:11PM +0200, Florian Westphal wrote:
> Artem Savkov <asavkov@xxxxxxxxxx> wrote:
> > It is possible for ebt_in_hook to be triggered before ebt_table is assigned
> > resulting in a NULL-pointer dereference. Make sure hooks are
> > registered as the last step.
>
> Right, thanks for the patch.
>
> > --- a/net/bridge/netfilter/ebtable_broute.c
> > +++ b/net/bridge/netfilter/ebtable_broute.c
> > @@ -65,7 +65,7 @@ static int ebt_broute(struct sk_buff *skb)
> >
> > static int __net_init broute_net_init(struct net *net)
> > {
> > - net->xt.broute_table = ebt_register_table(net, &broute_table, NULL);
> > + net->xt.broute_table = ebt_register_table(net, &broute_table);
>
> I wonder if it makes more sense to model this like the iptables version,
> i.e. pass net->xt.table_name as last arg to ebt_register_table ...
>
> > +int ebt_register_hooks(struct net *net, struct ebt_table *table,
> > + const struct nf_hook_ops *ops)
> > +{
> > + int ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
> > +
> > + if (ret)
> > + __ebt_unregister_table(net, table);
> > +
> > + return ret;
> > +}
>
> ... because this looks strange (unregister of table/not-so-obvious error
> unwinding ...)
>
> > @@ -1252,15 +1262,6 @@ ebt_register_table(struct net *net, const struct ebt_table *input_table,
> > list_add(&table->list, &net->xt.tables[NFPROTO_BRIDGE]);
> > mutex_unlock(&ebt_mutex);
>
> ... here one could then assign the net->xt.table_X pointer, and then do
> the hook registration right after.
>
> However i have no strong opinion here.
Agreed, that does look better and requires less changes. I'll send a v2.
--
Regards,
Artem
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