Message-ID: <4546BE24.5000504@sgi.com>
Date: Mon, 30 Oct 2006 19:08:20 -0800
From: Jay Lan <jlan@sgi.com>
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To: Oleg Nesterov <oleg@tv-sign.ru>
CC: Jay Lan <jlan@engr.sgi.com>, Andrew Morton <akpm@osdl.org>,
       Shailabh Nagar <nagar@watson.ibm.com>, Balbir Singh <balbir@in.ibm.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] xacct_add_tsk: fix pure theoretical ->mm use-after-free
References: <20061029185826.GA1619@oleg> <454649CE.80804@engr.sgi.com> <20061030204125.GB677@oleg>
In-Reply-To: <20061030204125.GB677@oleg>
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Oleg Nesterov wrote:
> On 10/30, Jay Lan wrote:
>> Oleg Nesterov wrote:
>>> Paranoid fix. The task can free its ->mm after the 'if (p->mm)' check.
>> Why this change is necessary? This routine is indirectly invoked by
>> taskstats_exit_send() routine called inside do_exit():
> 
> Not only, please note
> 
> 	taskstats_user_cmd(TASKSTATS_CMD_ATTR_PID)->fill_pid()->xacct_add_tsk()
> 
> path. This tsk is not 'current', it was found by find_task_by_pid(), and
> it may exit at any time.

OK. Thanks!

Acked-by: Jay Lan <jlan@sgi.com>

> 
> Oleg.
> 

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