Date: Fri, 25 Jun 2010 11:37:33 -0700
From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       Pavel Emelyanov <xemul@openvz.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linux Containers <containers@lists.osdl.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH] pid_ns: Fix proc_flush_task() accessing freed
	proc_mnt
Message-ID: <20100625183733.GA2627@us.ibm.com>
References: <20100623203652.GA25298@redhat.com> <1277399329-18087-1-git-send-email-louis.rilling@kerlabs.com> <20100624191843.GA14205@redhat.com> <20100625102303.GG3773@hawkmoon.kerlabs.com>
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Louis Rilling [Louis.Rilling@kerlabs.com] wrote:
| - proc_pid_readdir():
|   Needs similar check and protection to proc_pid_lookup(), but there is another
|   issue: next_tgid() can find a dying task:

Hmm, I thought proc_pid_readdir() would be a problem too but convinced myself
that it would not - since a process running proc_pid_readdir() would have
a reference to the pid namespace, in which case destroy_pid_ns() would not
be called.
| 
|   next_tgid() finds a task
|                                    task dies
|                                    last reference to ns is dropped
|                                    destroy_pid_namespace()

caller of next_tgid() holds a ref to pid-ns right ?

Sukadev
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