linux-kernel - Re: [PATCH] cgroup: fix use-after-free when umounting cgroupfs

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Date:	Fri, 26 Apr 2013 11:59:23 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Li Zefan <lizefan@...wei.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCH] cgroup: fix use-after-free when umounting cgroupfs

On Fri, Apr 26, 2013 at 10:54:11AM +0800, Li Zefan wrote:
> Try:
>   # mount -t cgroup xxx /cgroup
>   # mkdir /cgroup/sub && rmdir /cgroup/sub && umount /cgroup
> 
> And you might see this:
> 
> ida_remove called for id=1 which is not allocated.
> 
> It's because cgroup_kill_sb() is called to destroy root->cgroup_ida
> and free cgrp->root before ida_simple_removed() is called. What's
> worse is we're accessing cgrp->root while it has been freed.
> 
> Signed-off-by: Li Zefan <lizefan@...wei.com>

Applied to cgroup/for-3.10.

Thanks.

-- 
tejun
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