Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756661Ab0FYVzw (ORCPT ); Fri, 25 Jun 2010 17:55:52 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:58875 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996Ab0FYVzv (ORCPT ); Fri, 25 Jun 2010 17:55:51 -0400 Date: Fri, 25 Jun 2010 15:07:13 -0700 From: Sukadev Bhattiprolu To: Oleg Nesterov Cc: "Eric W. Biederman" , Pavel Emelyanov , Andrew Morton , Linux Containers , linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH] pid_ns: Fix proc_flush_task() accessing freed proc_mnt Message-ID: <20100625220713.GA31123@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> <20100625183733.GA2627@us.ibm.com> <20100625192945.GA25532@redhat.com> <20100625212618.GA11917@us.ibm.com> <20100625212758.GA30474@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100625212758.GA30474@redhat.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1284 Lines: 38 Oleg Nesterov [oleg@redhat.com] wrote: | On 06/25, Sukadev Bhattiprolu wrote: | > | > Oleg Nesterov [oleg@redhat.com] wrote: | > | On 06/25, Sukadev Bhattiprolu wrote: | > | > | > | > 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, | > | | > | Where does this reference comes from ? | > | > Caller of proc_pid_readdir() would be living in the same pid namespace right ? | | Afaics, in general not. | | Suppose that we do something like | | if (!clone(CLONE_NEWPID)) { | mount("none", "/SUB_PROC", "proc", 0, NULL); | exit(); | } | | After that /SUB_PROC/ still exists, one can do "ls /SUB_PROC/". Yes, I see it now. Thanks, Sukadev -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/