From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42060) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WUd1b-0001at-Qr for qemu-devel@nongnu.org; Mon, 31 Mar 2014 10:17:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WUd1W-0000op-Rx for qemu-devel@nongnu.org; Mon, 31 Mar 2014 10:17:19 -0400 Date: Mon, 31 Mar 2014 17:17:36 +0300 From: "Michael S. Tsirkin" Message-ID: <1396275242-10810-26-git-send-email-mst@redhat.com> References: <1396275242-10810-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1396275242-10810-1-git-send-email-mst@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v4 25/30] virtio-scsi: fix buffer overrun on invalid state load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: mdroth@linux.vnet.ibm.com, qemu-stable@nongnu.org, dgilbert@redhat.com, Anthony Liguori , Paolo Bonzini , =?us-ascii?B?PT9VVEYtOD9xP0FuZHJlYXM9MjBGPUMzPUE0cmJlcj89?= CVE-2013-4542 hw/scsi/scsi-bus.c invokes load_request. virtio_scsi_load_request does: qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem)); this probably can make elem invalid, for example, make in_num or out_num huge, then: virtio_scsi_parse_req(s, vs->cmd_vqs[n], req); will do: if (req->elem.out_num > 1) { qemu_sgl_init_external(req, &req->elem.out_sg[1], &req->elem.out_addr[1], req->elem.out_num - 1); } else { qemu_sgl_init_external(req, &req->elem.in_sg[1], &req->elem.in_addr[1], req->elem.in_num - 1); } and this will access out of array bounds. Note: this adds security checks within assert calls since SCSIBusInfo's load_request cannot fail. For now simply disable builds with NDEBUG - there seems to be little value in supporting these. Cc: Andreas F=E4rber Signed-off-by: Michael S. Tsirkin --- hw/scsi/virtio-scsi.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index b0d7517..1752193 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -147,6 +147,15 @@ static void *virtio_scsi_load_request(QEMUFile *f, S= CSIRequest *sreq) qemu_get_be32s(f, &n); assert(n < vs->conf.num_queues); qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem)); + /* TODO: add a way for SCSIBusInfo's load_request to fail, + * and fail migration instead of asserting here. + * When we do, we might be able to re-enable NDEBUG below. + */ +#ifdef NDEBUG +#error building with NDEBUG is not supported +#endif + assert(req->elem.in_num <=3D ARRAY_SIZE(req->elem.in_sg)); + assert(req->elem.out_num <=3D ARRAY_SIZE(req->elem.out_sg)); virtio_scsi_parse_req(s, vs->cmd_vqs[n], req); =20 scsi_req_ref(sreq); --=20 MST