From: Vasiliy Kulikov <segoon@openwall.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <bsingharora@gmail.com>,
Jerome Marchand <jmarchan@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] taskstats: add_del_listener() should ignore !valid listener's
Date: Wed, 20 Jul 2011 23:46:03 +0400 [thread overview]
Message-ID: <20110720194603.GA3385@albatros> (raw)
In-Reply-To: <20110720190036.GB21753@redhat.com>
On Wed, Jul 20, 2011 at 21:00 +0200, Oleg Nesterov wrote:
> When send_cpu_listeners() finds the orphaned listener it marks
> it as !valid and drops listeners->sem. Before it takes this sem
> for wrinting, s->pid can be reused and add_del_listener() can
> wrongly try to re-use this entry.
>
> Change add_del_listener() to check ->valid = T.
I think the current logic is wrong. If s was claimed is invalid, it
then points to a dead task, it is unknown when it died. As the same pid
can be reused by a new process BEFORE add_del_listener(), it is unknown
whether ->pid points to the actual owner task.
Rather than optimizing the wrong algorithm it's better to change the
processes keeping way.
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
next prev parent reply other threads:[~2011-07-20 19:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 18:59 [PATCH 0/2] 26c4caea "don't allow duplicate entries in listener mode" fix Oleg Nesterov
2011-07-20 19:00 ` [PATCH 1/2] taskstats: add_del_listener() shouldn't use the wrong node Oleg Nesterov
2011-07-20 19:50 ` Vasiliy Kulikov
2011-07-21 12:28 ` Jerome Marchand
2011-07-20 19:00 ` [PATCH 2/2] taskstats: add_del_listener() should ignore !valid listener's Oleg Nesterov
2011-07-20 19:46 ` Vasiliy Kulikov [this message]
2011-07-20 21:01 ` Oleg Nesterov
2011-07-21 12:50 ` Vasiliy Kulikov
2011-07-21 14:29 ` Oleg Nesterov
2011-07-21 15:49 ` Balbir Singh
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