linux-kernel - Re: [PATCH 1/1] pid_ns: move pid_ns_release_proc() from proc_flush_task() to zap_pid_ns

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Message-ID: <20100624130111.GB7257@redhat.com>
Date:	Thu, 24 Jun 2010 15:01:11 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Louis Rilling <louis.rilling@...labs.com>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Linux Containers <containers@...ts.osdl.org>,
	linux-kernel@...r.kernel.org,
	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Subject: Re: [PATCH 1/1] pid_ns: move pid_ns_release_proc() from
	proc_flush_task() to zap_pid_ns_processes()

On 06/24, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@...hat.com> writes:
>
> > This is mostly cleanup and optimization, but also fixes the bug.
>
> Oleg with respect to your other patches I think they are some of
> the best ones we have on the table.
>
> > proc_flush_task() checks upid->nr == 1 to detect the case when
> > a sub-namespace exits. However, this doesn't work in case when
> > a multithreaded init execs and calls release_task(old_leader),
> > the old leader has the same pid 1.
> >
> > Move pid_ns_release_proc() to zap_pid_ns_processes(), it is called
> > when we know for sure that init is exiting.
>
> This actually guarantees a use after free for the namespace init:

Yes, thanks. I am stupid.

Please ignore the patch.

Oleg.

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