Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

From: "H. Peter Anvin" <hpa@zytor.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: "Klaus S. Madsen" <ksm@hjernemadsen.org>,
	Suspend-devel list <suspend-devel@lists.sourceforge.net>,
	Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	Thomas Gleixner <tglx@linutronix.de>,
	mjg59@srcf.ucam.org
Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending
Date: Mon, 03 Mar 2008 09:50:09 -0800	[thread overview]
Message-ID: <47CC3A51.60209@zytor.com> (raw)
In-Reply-To: <20080303174724.GC13869@elf.ucw.cz>

Pavel Machek wrote:
> On Mon 2008-03-03 09:10:35, H. Peter Anvin wrote:
>> Pavel Machek wrote:
>>>> The only thing I don't understand is why this is suddenly a problem with
>>>> 2.6.25, and not with 2.6.24? Is there a bug in 2.6.24 and previously
>>>> that allows real-mode execution of non-executable pages?
>>> It is strange indeed... Should it be traced as an regression?
>> I'd like to understand what the heck happened, but as far as we can observe 
>> right now, it's a *progression*, not a regression, since executing out of a 
>> non-PROT_EXEC area isn't *supposed* to work...
> 
> Okay, I guess this depends on the eye of the beholder... because s2ram
> *is* supposed to work ;-).
> 
> Ideally, I'd like to keep 2.6.24 behaviour for at least a while, so we
> can try to fix the libx86 out there or something...
> 									Pavel
> PS: Matthew, there's problem in libx86: it tries to execute from area
> not marked as PROT_EXEC.

Allowing execution of a PROT_EXEC area is a security hole.  The fact 
that you happened to benefit from it doesn't change its nature as a 
security hole.

	-hpa