From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1Nrrjg-0004zR-5y
	for qemu-devel@nongnu.org; Wed, 17 Mar 2010 07:48:28 -0400
Received: from [199.232.76.173] (port=42373 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Nrrjf-0004z9-ED
	for qemu-devel@nongnu.org; Wed, 17 Mar 2010 07:48:27 -0400
Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim
	4.60) (envelope-from <nchip@afflict.kos.to>) id 1Nrrjd-0003P2-V4
	for qemu-devel@nongnu.org; Wed, 17 Mar 2010 07:48:27 -0400
Received: from afflict.kos.to ([92.243.29.197]:47207)
	by monty-python.gnu.org with esmtps
	(TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60)
	(envelope-from <nchip@afflict.kos.to>) id 1Nrrjd-0003OH-2v
	for qemu-devel@nongnu.org; Wed, 17 Mar 2010 07:48:25 -0400
Date: Wed, 17 Mar 2010 11:48:07 +0000
From: Riku Voipio <riku.voipio@iki.fi>
Subject: Re: [Qemu-devel] [PATCH 0/6] Multi-level page tables and userland
	mapping fixes, v3
Message-ID: <20100317114807.GA13278@afflict.kos.to>
References: <cover.1268265556.git.rth@twiddle.net>
	<201003151346.10470.dl9pf@gmx.de>
	<20100315144803.GA1895@afflict.kos.to>
	<201003151608.46624.dl9pf@gmx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <201003151608.46624.dl9pf@gmx.de>
Content-Transfer-Encoding: quoted-printable
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Jan-Simon =?utf-8?Q?M=C3=B6ller?= <dl9pf@gmx.de>
Cc: Martin Mohring <martin.mohring@opensuse.org>, Riku Voipio <riku.voipio@iki.fi>, qemu-devel@nongnu.org, Aurelien Jarno <aurelien@aurel32.net>, Richard Henderson <rth@twiddle.net>

On Mon, Mar 15, 2010 at 04:08:46PM +0100, Jan-Simon M=C3=B6ller wrote:
> Am Montag, 15. M=C3=A4rz 2010 15:48:03 schrieb Riku Voipio:
> > On Mon, Mar 15, 2010 at 01:46:10PM +0100, Jan-Simon M=C3=B6ller wrote=
:
> > > root@frodo:/# qemu-arm -strace /sbin/ldconfig.real
> > > 16359 uname(0x403fef78) =3D 0
> > > 16359 brk(NULL) =3D 0x000a9000
> > > 16359 brk(0x000a9d08) =3D 0x000a9d08
> > > 16359 open("/dev/urandom",O_RDONLY) =3D 3
> > > 16359 read(3,0x403ff27d,3) =3D 3
> > > 16359 close(3) =3D 0
> > > [...]
> > > 16359 stat64("/usr/lib/libgettextlib.so",0x403fdf28) =3D 0
> > > 16359 stat64("/usr/lib/libgettextpo.so.0",0x403fdec0) =3D 0
> > > 16359 stat64("/usr/lib/libgettextpo.so.0.4.0",0x403fdf28) =3D 0
> > > 16359 stat64("/usr/lib/libpython2.6.so.1.0",0x403fdec0) =3D 0
> > > 16359 stat64("/usr/lib/libpython2.6.so.1.0",0x403fdf28) =3D 0
> > > 16359 open("/etc/ld.so.cache~",O_WRONLY|O_CREAT|O_NOFOLLOW|O_TRUNC,=
0600)
> > > =3D 3 16359 write(3,0xb03d0,1288) =3D 1288
> > > 16359 write(3,0x403ff0a0,0) =3D -1 errno=3D14 (Bad address)
=20
> > A zero sized write. According to manpage ok.
=20
> > In qemu we do a lock_user to to get the string to write. Richards cha=
nge
> >  changes the access checks the get called by lock_user:

> > page_check_range:
> >=20
> > -    if (start + len < start)
> > -        /* we've wrapped around */
> > ...
> > +    if (start + len - 1 < start) {
> > +        /* We've wrapped around.  */
> >=20
> > This now blows up with len =3D 0;

> Confirmed. A quick test with  if (len > 0) around and ldconfig.real run=
s.

Richard, would you be ok with that change? Or should we rather have expli=
cit=20

if (len =3D=3D 0) return 0;

?