On Sat, Jul 09, 2016 at 01:30:38AM +0200, Florian Westphal wrote:
> Aaron Conole <aconole@xxxxxxxxxx> wrote:
> > --- a/net/netfilter/core.c
> > +++ b/net/netfilter/core
> [..]
> > +#define nf_entry_dereference(e) \
> > + rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
> >
> > -static struct list_head *nf_find_hook_list(struct net *net,
> > - const struct nf_hook_ops *reg)
> > +static struct nf_hook_entry *nf_find_hook_list(struct net *net,
> > + const struct nf_hook_ops *reg)
> > {
> > - struct list_head *hook_list = NULL;
> > + struct nf_hook_entry *hook_list = NULL;
> >
> > if (reg->pf != NFPROTO_NETDEV)
> > - hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
> > + hook_list = rcu_dereference(net->nf.hooks[reg->pf]
> > + [reg->hooknum]);
> > else if (reg->hooknum == NF_NETDEV_INGRESS) {
> > #ifdef CONFIG_NETFILTER_INGRESS
> > if (reg->dev && dev_net(reg->dev) == net)
> > - hook_list = ®->dev->nf_hooks_ingress;
> > + hook_list =
> > + rcu_dereference(reg->dev->nf_hooks_ingress);
>
> Both of these should use nf_entry_dereference() to avoid the lockdep
> splat reported by kbuild robot:
>
> net/netfilter/core.c:75 suspicious rcu_dereference_check() usage!
> 2 locks held by swapper/1:
> #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff81c2e567>] rtnl_lock+0x17/0x20
> #1: (nf_hook_mutex){+.+...}, at: [<ffffffff81c58fcb>] nf_register_net_hook+0xcb/0x240
Aaron, please, send a v2.
I have a patchset that changes the footprint of the hook function as
it was discussed during the last Netfilter Workshop that clashes with
this.
Thanks!
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