From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:51014)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1S2Jbl-0004ap-R2
	for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:44:36 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1S2JbW-0005nd-Dy
	for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:44:33 -0500
Received: from mx1.redhat.com ([209.132.183.28]:12086)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1S2JbW-0005nU-5U
	for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:44:18 -0500
Message-ID: <4F4CA2C1.7070708@redhat.com>
Date: Tue, 28 Feb 2012 10:47:45 +0100
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <1330360065-27334-1-git-send-email-kwolf@redhat.com>
	<CAJSP0QWspNM+ESSGjzW1KSXcHJp8RUU+BQxrRzwyZ6cqPVMx1g@mail.gmail.com>
In-Reply-To: <CAJSP0QWspNM+ESSGjzW1KSXcHJp8RUU+BQxrRzwyZ6cqPVMx1g@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH] qcow2: Reject unrealistically large header
 extensions
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: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel@nongnu.org

Am 28.02.2012 10:33, schrieb Stefan Hajnoczi:
> On Mon, Feb 27, 2012 at 4:27 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> +        if (ext.len > 65536) {
>> +            error_report("Header extension larger than 64k - this looks wrong");
>> +            return -ENOTSUP;
>> +        }
> 
> This is an implementation limit and not in the spec, but I think it's
> reasonable.
> 
> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Hm, actually, now that I look at this patch again, I think there's a
much better error condition that even matches the spec:

    if (offset + ext.len > end_offset)

I'll send a changed version of the patch.

Kevin