From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:56779)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <afaerber@suse.de>) id 1Un3kF-0007qi-TB
	for qemu-devel@nongnu.org; Thu, 13 Jun 2013 05:23:05 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <afaerber@suse.de>) id 1Un3kD-0002cu-GH
	for qemu-devel@nongnu.org; Thu, 13 Jun 2013 05:23:03 -0400
Received: from cantor2.suse.de ([195.135.220.15]:47068 helo=mx2.suse.de)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <afaerber@suse.de>) id 1Un3kD-0002cF-Al
	for qemu-devel@nongnu.org; Thu, 13 Jun 2013 05:23:01 -0400
Message-ID: <51B98F70.3070009@suse.de>
Date: Thu, 13 Jun 2013 11:22:56 +0200
From: =?ISO-8859-1?Q?Andreas_F=E4rber?= <afaerber@suse.de>
MIME-Version: 1.0
References: <51B96205.4010601@kamp.de>
In-Reply-To: <51B96205.4010601@kamp.de>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Qemu-devel] [RFC] sanitize memory on system reset
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Peter Lieven <pl@kamp.de>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Hi,

Am 13.06.2013 08:09, schrieb Peter Lieven:
> I was thinking if it would be a good idea to zeroize all memory
> resources on system reset and
> madvise dontneed them afterwards.

The current way of not zeroing memory has led to discovery of some
firmware bugs that we wouldn't have found if QEMU defaulted to zeroing.

> This would avoid system reset attacks
> in case the attacker
> has only access to the console of a vServer but not on the physical hos=
t
> and it would shrink
> RSS size of the vServer siginificantly.

Apart from the guest issue Stefan brought up (so far by definition we do
a hard reset, so guests cannot assume soft reset semantics, but we
should keep our options open), would not zeroing while marking pages as
unused be an option? E.g., -reset-memory=3DDEADBEEF or some other
command-line-specifiable pattern, absence would mean current behavior.

Regards,
Andreas

--=20
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrnbe=
rg