From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: [KVM PATCH v8 3/3] KVM: add iosignalfd support Date: Mon, 22 Jun 2009 09:19:57 -0400 Message-ID: <4A3F84FD.3090700@gmail.com> References: <20090619002224.15859.97977.stgit@dev.haskins.net> <20090619003045.15859.73197.stgit@dev.haskins.net> <20090622104435.GA11594@redhat.com> <4A3F757C.6030508@novell.com> <20090622123022.GC12867@redhat.com> <4A3F8170.7000508@gmail.com> <20090622131351.GE12867@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig9831ACCC4F115803D27E67A4" Cc: Gregory Haskins , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com, mtosatti@redhat.com, paulmck@linux.vnet.ibm.com, markmc@redhat.com To: "Michael S. Tsirkin" Return-path: Received: from yw-out-2324.google.com ([74.125.46.31]:28815 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255AbZFVNUD (ORCPT ); Mon, 22 Jun 2009 09:20:03 -0400 In-Reply-To: <20090622131351.GE12867@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig9831ACCC4F115803D27E67A4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Michael S. Tsirkin wrote: > On Mon, Jun 22, 2009 at 09:04:48AM -0400, Gregory Haskins wrote: > =20 >> Sorry, Michael. I missed that you had other comments after the >> grammatical one. Will answer inline >> >> Michael S. Tsirkin wrote: >> =20 >>> On Mon, Jun 22, 2009 at 08:13:48AM -0400, Gregory Haskins wrote: >>> =20 >>> =20 >>> >>>> If thats true, we are in trouble ;) >>>> =20 >>>> =20 >>> I think it works at least on x86: >>> http://en.wikipedia.org/wiki/Packed#x86_and_x86-64 >>> =20 >>> =20 >> Right, understood. What I meant specifically is that if the (void*)va= l >> pointer is allowed to be misaligned we are in trouble ;). I haven't >> studied the implementation in front of the MMIO callback recently, but= I >> generally doubt thats the case. More than likely this is some buffer >> that was kmalloced and that should already be aligned to the machine w= ord. >> >> Kind Regards, >> -Greg >> >> =20 > > Yes, from what I saw of the code I think it can be BUG_ON. > Avi? > > =20 The question to ask is whether a guest can influence that condition. If they can, its an attack vector to crash the host. I suspect they can't, however. Therefore, your recommendation is perhaps a good approach so this condition cannot ever go unnoticed. Avi? -Greg --------------enig9831ACCC4F115803D27E67A4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAko/hP0ACgkQP5K2CMvXmqEOjACfV/cMVIAUoycWu1N0+0aS440N 7JcAnA2p/4jmgY9HWnK/SFVYvNBYEbag =Rv2O -----END PGP SIGNATURE----- --------------enig9831ACCC4F115803D27E67A4--