linux-kernel - Re: [RESEND] [BUG] futex_unlock_pi() hurts my brain and may cause application deadlock

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]

Date:	Tue, 31 Jul 2007 20:00:05 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	john stultz <johnstul@...ibm.com>
cc:	Ingo Molnar <mingo@...e.hu>, lkml <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sripathi Kodi <sripathik@...ibm.com>
Subject: Re: [RESEND] [BUG] futex_unlock_pi() hurts my brain and may cause
 application deadlock



--
On Tue, 31 Jul 2007, john stultz wrote:

> On Wed, 2007-05-30 at 17:49 -0700, john stultz wrote:
>
> Hey Ingo,
> 	I sent this fix for this back in the 2.6.21-rt9 era, and I thought to
> picked it up, but I think it arrived amid some futex churn and
> apparently has been dropped or was just lost.
>
> Some of our testers have been reporting futex deadlocks and this fix
> resolves it, so I believe it to still be needed.

Heh, I remember this bug.  Wasn't there another patch that modified this.
I almost definitly remember this getting into the patch queue, but it must
have been dropped later.

John, thanks for looking into this deeper!

Acked-by: Steven Rostedt <rostedt@...dmis.org>

>
> thanks
> -john
>
> Avoid futex_unlock_pi returning -EFAULT (which results in deadlock), by
> clearing uval before jumping to retry_locked.
>
> Signed-off-by: John Stultz <johnstul@...ibm.com>
> Index: 2.6-rt/kernel/futex.c
> ===================================================================
> --- 2.6-rt.orig/kernel/futex.c	2007-07-31 16:48:41.000000000 -0700
> +++ 2.6-rt/kernel/futex.c	2007-07-31 16:48:48.000000000 -0700
> @@ -1673,6 +1673,7 @@ pi_faulted:
>  					 attempt);
>  		if (ret)
>  			goto out;
> +		uval = 0;
>  		goto retry_unlocked;
>  	}
>
>
>
>
>
-
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/