linux-kernel - Re: [PATCH -mm 2/2] PM: Disable usermode helper before hibernation and suspend

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: <200706152336.46278.rjw@sisk.pl>
Date:	Fri, 15 Jun 2007 23:36:45 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Uli Luckas <u.luckas@...d.de>
Cc:	LKML <linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH -mm 2/2] PM: Disable usermode helper before hibernation and suspend

On Friday, 15 June 2007 15:08, Uli Luckas wrote:
> On Monday, 4. June 2007, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@...k.pl>
> >
> > Use a hibernation and suspend notifier to disable the user mode helper
> > before a hibernation/suspend and enable it after the operation.
> >
> Hi Rafael,
> I have a couple of questions, regarding this patch ...
> > -	if (!khelper_wq)
> > +	if (!khelper_wq || usermodehelper_disabled)
> >  		return -EBUSY;
> 1) how about not returning -EBUSY here, if (wait == UMH_NO_WAIT)?

Yes, this would make sense.

> 2) how does your patch prevent wait_for_completion(&done) to hang during
>    freezing if usermodehelper_pm_callback is called _after_ the above check?

It doesn't.  Once the helper is running, we can't distinguish it from any other
user land process.

Still, it narrows the window quite a bit.

Greetings,
Rafael

-- 
"Premature optimization is the root of all evil." - Donald Knuth
-
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/