From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39353) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1clXc6-0008BA-T0 for qemu-devel@nongnu.org; Wed, 08 Mar 2017 04:10:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1clXc2-0000hO-Qs for qemu-devel@nongnu.org; Wed, 08 Mar 2017 04:10:30 -0500 Received: from mx3-phx2.redhat.com ([209.132.183.24]:52517) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1clXc2-0000h6-IR for qemu-devel@nongnu.org; Wed, 08 Mar 2017 04:10:26 -0500 Date: Wed, 8 Mar 2017 04:10:26 -0500 (EST) From: Paolo Bonzini Message-ID: <519330901.29898313.1488964226313.JavaMail.zimbra@redhat.com> In-Reply-To: <61938aa1-2698-f55e-ea1c-e7d96da0b5d7@redhat.com> References: <1488876478-6889-1-git-send-email-jasowang@redhat.com> <313e32c5-140d-ec13-6b10-98043756f2e6@redhat.com> <61938aa1-2698-f55e-ea1c-e7d96da0b5d7@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] virtio: destroy region cache during reset List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: mst@redhat.com, qemu-devel@nongnu.org, peterx@redhat.com ----- Original Message ----- > From: "Jason Wang" > To: "Paolo Bonzini" , mst@redhat.com, qemu-devel@non= gnu.org > Cc: peterx@redhat.com > Sent: Wednesday, March 8, 2017 7:22:06 AM > Subject: Re: [Qemu-devel] [PATCH] virtio: destroy region cache during res= et >=20 >=20 >=20 > On 2017=E5=B9=B403=E6=9C=8808=E6=97=A5 11:21, Jason Wang wrote: > > > > On 2017=E5=B9=B403=E6=9C=8807=E6=97=A5 18:55, Paolo Bonzini wrote: > >> > >> On 07/03/2017 09:47, Jason Wang wrote: > >>> We don't destroy region cache during reset which can make the maps > >>> of previous driver leaked to a buggy or malicious driver that don't > >>> set vring address before starting to use the device. > >> I'm still not sure as to how this can happen. Reset does clear > >> desc/used/avail, which should then be checked before accessing the > >> caches. > > > > But the code does not check them in fact? (E.g the attached qtest > > patch can still pass check-qtest). > > > > Thanks >=20 > Ok, the reproducer seems wrong. And I think what you mean is something > like the check done in virtio_queue_ready(). But looks like not all > virtqueue check for this. One example is virtio_net_handle_ctrl(), and > there may be even more. So you want to fix them all? Why would virtio_net_handle_ctrl be called when desc =3D=3D 0? The checks are all in common virtio code. static void virtio_queue_notify_vq(VirtQueue *vq) { if (vq->vring.desc && vq->handle_output) { VirtIODevice *vdev =3D vq->vdev; if (unlikely(vdev->broken)) { return; } trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); vq->handle_output(vdev, vq); } } = = 1440,29 55% Paolo