From: john stultz <johnstul@us.ibm.com>
To: dedekind1@gmail.com
Cc: Oleg Nesterov <oleg@redhat.com>,
Kees Cook <kees.cook@canonical.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Neil Horman <nhorman@tuxdriver.com>,
Roland McGrath <roland@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sanitize task->comm to avoid leaking escape codes
Date: Tue, 29 Jun 2010 15:32:11 -0700 [thread overview]
Message-ID: <1277850731.1821.44.camel@localhost> (raw)
In-Reply-To: <1277787505.3599.25.camel@localhost.localdomain>
On Tue, 2010-06-29 at 07:58 +0300, Artem Bityutskiy wrote:
> On Wed, 2010-06-23 at 21:41 +0200, Oleg Nesterov wrote:
> > On 06/23, Kees Cook wrote:
> > >
> > > @@ -956,7 +957,15 @@ void set_task_comm(struct task_struct *tsk, char *buf)
> > > */
> > > memset(tsk->comm, 0, TASK_COMM_LEN);
> > > wmb();
> >
> > Off-topic. I'd wish I could understand this barrier. Since the lockless
> > reader doesn't do rmb() I don't see how this can help.
>
> This wmb() looks wrong to me as well. To achieve what the comment in
> this function says, it should be smp_wmb() and we should have smp_rmb()
> in the reading side, AFAIU.
>
> > OTOH, I don't
> > understand why it is needed, we never change ->comm[TASK_COMM_LEN-1] == '0'.
>
> I think the idea was that readers can see incomplete names, but not
> messed up names, consisting of old and new ones.
Yes, that was the intent, but I do see how it is unnecessary.
So I'm fine with it and the memset being removed.
Thanks for catching this!
-john
prev parent reply other threads:[~2010-06-29 22:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-23 18:11 [PATCH] sanitize task->comm to avoid leaking escape codes Kees Cook
2010-06-23 19:41 ` Oleg Nesterov
2010-06-23 20:23 ` Alexey Dobriyan
2010-06-23 21:28 ` Kees Cook
2010-06-28 20:00 ` Andrew Morton
2010-06-28 21:03 ` Kees Cook
2010-06-29 8:45 ` Alexey Dobriyan
2010-06-29 15:09 ` Kees Cook
2010-06-29 18:59 ` Andrew Morton
2010-06-29 19:13 ` Kees Cook
2010-06-29 4:58 ` Artem Bityutskiy
2010-06-29 13:31 ` Oleg Nesterov
2010-06-29 16:23 ` Paul E. McKenney
2010-06-29 17:18 ` Oleg Nesterov
2010-06-29 17:33 ` Paul E. McKenney
2010-06-29 22:32 ` john stultz [this message]
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