From: Florian Westphal <fw@strlen.de>
To: dwilder <dwilder@us.ibm.com>
Cc: Florian Westphal <fw@strlen.de>,
netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
wilder@us.ibm.com, mkubecek@suse.com
Subject: Re: [(RFC) PATCH ] NULL pointer dereference on rmmod iptable_mangle.
Date: Thu, 4 Jun 2020 12:38:15 +0200 [thread overview]
Message-ID: <20200604103815.GE28263@breakpoint.cc> (raw)
In-Reply-To: <72692f32471b5d2eeef9514bb2c9ba51@linux.vnet.ibm.com>
dwilder <dwilder@us.ibm.com> wrote:
> > Since the netns core already does an unconditional synchronize_rcu after
> > the pre_exit hooks this would avoid the problem as well.
>
> Something like this? (un-tested)
Yes.
> diff --git a/net/ipv4/netfilter/iptable_mangle.c
> b/net/ipv4/netfilter/iptable_mangle.c
> index bb9266ea3785..0d448e4d5213 100644
> --- a/net/ipv4/netfilter/iptable_mangle.c
> +++ b/net/ipv4/netfilter/iptable_mangle.c
> @@ -100,15 +100,26 @@ static int __net_init iptable_mangle_table_init(struct
> net *net)
> return ret;
> }
>
> +static void __net_exit iptable_mangle_net_pre_exit(struct net *net)
> +{
> + struct xt_table *table = net->ipv4.iptable_mangle;
> +
> + if (mangle_ops)
> + nf_unregister_net_hooks(net, mangle_ops,
> + hweight32(table->valid_hooks));
> +}
You probably need if (table) here, not mangle_ops.
I'm not sure if it makes sense to add a new
xt_unregister_table_hook() helper, I guess one would have to try
and see if that reduces copy&paste programming or not.
> static void __net_exit iptable_mangle_net_exit(struct net *net)
> {
> if (!net->ipv4.iptable_mangle)
> return;
> - ipt_unregister_table(net, net->ipv4.iptable_mangle, mangle_ops);
> + ipt_unregister_table(net, net->ipv4.iptable_mangle, NULL);
I guess the 3rd arg could be removed from the helper.
But yes, this looks like what I had in mind.
next prev parent reply other threads:[~2020-06-04 10:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 21:25 [(RFC) PATCH ] NULL pointer dereference on rmmod iptable_mangle David Wilder
2020-06-03 22:05 ` Florian Westphal
2020-06-04 6:00 ` dwilder
2020-06-04 10:38 ` Florian Westphal [this message]
2020-06-15 11:44 ` Florian Westphal
2020-06-15 16:21 ` dwilder
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