linux-kernel - Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120410225431.GN24857@moon>
Date:	Wed, 11 Apr 2012 02:54:31 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Andrey Vagin <avagin@...nvz.org>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Glauber Costa <glommer@...allels.com>,
	Andi Kleen <andi@...stfloor.org>, Tejun Heo <tj@...nel.org>,
	Matt Helsley <matthltc@...ibm.com>,
	Pekka Enberg <penberg@...nel.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Vasiliy Kulikov <segoon@...nwall.com>,
	Alexey Dobriyan <adobriyan@...il.com>, Valdis.Kletnieks@...edu,
	Michal Marek <mmarek@...e.cz>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>
Subject: Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree

On Mon, Apr 09, 2012 at 08:25:22PM -0700, Eric W. Biederman wrote:
...
> 
> Having just read through it again the only possible issue I can see is
> that we compare file descriptors after dropping all of the locks.
> 
> Since rcu_read_lock doesn't participate in ABBA deadlocks. My gut feel
> is that we should hold rcu_read_lock across the hole file pointer
> comparison to remove the possibility of races as file descriptor
> pointers go away.
> 
> Still in practice I don't think it matters.  At worst there is the
> slightest possibility of returning a value instead of -EBADF.  The
> expectation is for all of the tasks we are operating on to be frozen,
> and even if the tasks are not frozen it is a very tiny window for a race
> to be in.

yeah, we use this call heavily on stopped tasks atm

> > So what do people think?  Any issues?  Any nacks?  Should I sneak it
> > into Linus this week or do we need to go another round with it all?
> 
> Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> 

Thanks a lot, Eric!

	Cyrill
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/