[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20110703200106.GB9714@albatros>
Date: Mon, 4 Jul 2011 00:01:06 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
viro@...iv.linux.org.uk, rientjes@...gle.com, wilsons@...rt.ca,
security@...nel.org, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH] proc: fix a race in do_io_accounting()
On Sun, Jul 03, 2011 at 12:24 -0700, Linus Torvalds wrote:
> On Sun, Jul 3, 2011 at 3:39 AM, Vasiliy Kulikov <segoon@...nwall.com> wrote:
> >
> > The order of locking is similar to the one inside of
> > ptrace_attach(): first goes cred_guard_mutex, then lock_task_sighand().
>
> Hmm. mm_for_maps() uses mutex_lock_killable(), as does lock_trace.
Killable/interruptable here makes sense.
> And neither proc_pid_wchan() nor the fd following ones
> (proc_pid_follow_link etc) use anything at all.
>
> So I'm not sure. And do we really even care about the theoretical
> race? Even if we do hit the race window and happen to get it just as a
> process turns setuid, it would seem to be totally harmless (we're not
> going to see any of the sensitive IO anyway).
I consider this as a theoretical race too unless there is a crazy bug in
scheduler/timer. But IMO it's better to just fully remove the risk
(even purely theoretical) given the lock is simple and it doesn't cost
much.
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
