From: Tejun Heo <tj@kernel.org>
To: Li Zefan <lizefan@huawei.com>
Cc: cgroups <cgroups@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] cgroup: fix exit() vsrmdir() race
Date: Thu, 24 Jan 2013 10:19:23 -0800 [thread overview]
Message-ID: <20130124181923.GK2373@mtj.dyndns.org> (raw)
In-Reply-To: <5100D810.5020406@huawei.com>
On Thu, Jan 24, 2013 at 02:43:28PM +0800, Li Zefan wrote:
> In cgroup_exit() put_css_set_taskexit() is called without any lock,
> which might lead to accessing a freed cgroup:
>
> thread1 thread2
> ---------------------------------------------
> exit()
> cgroup_exit()
> put_css_set_taskexit()
> atomic_dec(cgrp->count);
> rmdir();
> /* not safe !! */
> check_for_release(cgrp);
>
> rcu_read_lock() can be used to make sure the cgroup is alive.
>
> Signed-off-by: Li Zefan <lizefan@huawei.com>
Applying to cgroup/for-3.8-fixes w/ stable cc'd.
* Can you please add WARN_ON_ONCE(!rcu_read_lock_held()) in
check_for_release()?
* cgroup_release_agent() seems broken too. It's accessing cgrp after
removing it from release_list. Can you please fix it too?
Thanks.
--
tejun
next prev parent reply other threads:[~2013-01-24 18:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-24 6:43 [PATCH 1/2] cgroup: fix exit() vsrmdir() race Li Zefan
2013-01-24 6:43 ` [PATCH 2/2] cgroup: remove a NULL check in cgroup_exit() Li Zefan
2013-01-24 18:20 ` Tejun Heo
2013-01-24 18:19 ` Tejun Heo [this message]
2013-01-24 18:36 ` [PATCH 1/2] cgroup: fix exit() vsrmdir() race Tejun Heo
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