From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39777) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ya2HU-0004yL-6l for qemu-devel@nongnu.org; Mon, 23 Mar 2015 09:20:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ya2HP-0004up-Uh for qemu-devel@nongnu.org; Mon, 23 Mar 2015 09:20:36 -0400 Date: Mon, 23 Mar 2015 13:20:28 +0000 From: Stefan Hajnoczi Message-ID: <20150323132028.GG9268@stefanha-thinkpad.redhat.com> References: <1426831670-11080-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="oOB74oR0WcNeq9Zb" Content-Disposition: inline In-Reply-To: <1426831670-11080-1-git-send-email-jasowang@redhat.com> Subject: Re: [Qemu-devel] [PATCH for 2.3 V2] virtio-net: validate backend queue numbers against bus limitation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: mst@redhat.com, qemu-devel@nongnu.org, qemu-stable --oOB74oR0WcNeq9Zb Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Mar 20, 2015 at 02:07:50PM +0800, Jason Wang wrote: > We don't validate the backend queue numbers against bus limitation, > this will easily crash qemu if it exceeds the limitation which will > hit the abort() in virtio_del_queue(). An example is trying to > starting a virtio-net device with 256 queues. E.g: >=20 > ./qemu-system-x86_64 -netdev tap,id=3Dhn0,queues=3D256 -device > virtio-net-pci,netdev=3Dhn0 >=20 > Fixing this by doing the validation and fail early. >=20 > Cc: Michael S. Tsirkin > Cc: qemu-stable > Signed-off-by: Jason Wang > --- > Changes from V1: > Tweak the commit log. > --- > hw/net/virtio-net.c | 7 +++++++ > 1 file changed, 7 insertions(+) >=20 > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index 27adcc5..59f76bc 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -1588,6 +1588,13 @@ static void virtio_net_device_realize(DeviceState = *dev, Error **errp) > virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size); > =20 > n->max_queues =3D MAX(n->nic_conf.peers.queues, 1); > + if (n->max_queues * 2 + 1 > VIRTIO_PCI_QUEUE_MAX) { > + error_setg(errp, "Invalid number of queues (=3D %" PRIu32 "), " > + "must be a postive integer less than %d.", > + n->max_queues, (VIRTIO_PCI_QUEUE_MAX - 1) / 2); > + virtio_cleanup(vdev); > + return; > + } If VIRTIO_PCI_QUEUE_MAX is really PCI-only then this is a layering violation. Virtio devices should not assume a particular transport (PCI, CCW, etc). Either the constant should be renamed if it truly applies to all transports, or there should be a virtio_get_max_queues() function that lets the transport pick a value. That said, virtio-scsi.c already checks VIRTIO_PCI_QUEUE_MAX so maybe this patch is fine and a cleanup should be written later: Reviewed-by: Stefan Hajnoczi --oOB74oR0WcNeq9Zb Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJVEBMcAAoJEJykq7OBq3PIsk4IAJo+XETRSgFbEeVNSeW+Dd0E wLEhPU8vxUdLE1pSLoQ6ov7ogGGJBT0LYvenGQ+EGXwBf0nHXACRv7HyLCfH2Bi5 JmXy4SZpiGtA4noH0wj1N7tUNuJYnTlELNTyfqZpyP5uozy3lXXCC3pFqHZnjoe9 8xlFBB2+N8atUBeSELLJZmyejYc9bvxbGFxzyEzvSZG0MV9lQIOM1dMNzr7nBBT3 wAyuRL7sDjw/1gaY+xZ4TY8sIZiEkn93PX8LYVoDf2QvOIqXTwp1SBOdgwM1tXO9 17SgBo+YSsjLEd1xpL/IACoUbXnzSFIMahZvZA5upuRwDyyvMK8t8EpW0OrsSQg= =nshC -----END PGP SIGNATURE----- --oOB74oR0WcNeq9Zb--