From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Fastabend <john.r.fastabend@intel.com>
Subject: Re: [RFC PATCH] net: cgroup: null ptr dereference in netprio cgroup
 during init
Date: Tue, 17 Jul 2012 22:50:13 -0700
Message-ID: <50064E95.7020503@intel.com>
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Cc: davem@davemloft.net, nhorman@tuxdriver.com,
	mark.d.rustad@intel.com, netdev@vger.kernel.org,
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To: Gao feng <gaofeng@cn.fujitsu.com>
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On 7/17/2012 6:59 PM, Gao feng wrote:
> =E4=BA=8E 2012=E5=B9=B407=E6=9C=8818=E6=97=A5 08:33, John Fastabend =E5=
=86=99=E9=81=93:
>> When the netprio cgroup is built in the kernel cgroup_init will call
>> cgrp_create which eventually calls update_netdev_tables. This is
>> being called before do_initcalls() so a null ptr dereference occurs
>> on init_net.
>>

[...]

>
>
> Thanks John.
> It's my mistake.
>
> Can we make sure init_net.count is zero here?
> I can't find some places to initialize it to zero.
>

Its defined in net_namespace.c so it's zeroed by virtue
of being global. And initialized in setup_net via
pure_initcall() always after cgroup_init() if I've done
my accounting correctly.

=2EJohn