From patchwork Wed Apr 14 05:28:33 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 50111 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 01BF7B7D27 for ; Wed, 14 Apr 2010 16:13:24 +1000 (EST) Received: from localhost ([127.0.0.1]:40528 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1vok-0007pI-Oj for incoming@patchwork.ozlabs.org; Wed, 14 Apr 2010 02:11:18 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O1vC7-0002Se-2r for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:23 -0400 Received: from [140.186.70.92] (port=49111 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1vC5-0002S2-Kq for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O1vC4-00063a-1I for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19811) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O1vC3-00063S-Mi for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:20 -0400 Received: from int-mx05.intmail.prod.int.phx2.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o3E5VF7s019945 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 14 Apr 2010 01:31:15 -0400 Received: from localhost (vpn-236-230.phx2.redhat.com [10.3.236.230]) by int-mx05.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o3E5VCBE000784; Wed, 14 Apr 2010 01:31:13 -0400 From: Amit Shah To: Anthony Liguori Date: Wed, 14 Apr 2010 10:58:33 +0530 Message-Id: <1271222917-7803-14-git-send-email-amit.shah@redhat.com> In-Reply-To: <1271222917-7803-13-git-send-email-amit.shah@redhat.com> References: <1271222917-7803-1-git-send-email-amit.shah@redhat.com> <1271222917-7803-2-git-send-email-amit.shah@redhat.com> <1271222917-7803-3-git-send-email-amit.shah@redhat.com> <1271222917-7803-4-git-send-email-amit.shah@redhat.com> <1271222917-7803-5-git-send-email-amit.shah@redhat.com> <1271222917-7803-6-git-send-email-amit.shah@redhat.com> <1271222917-7803-7-git-send-email-amit.shah@redhat.com> <1271222917-7803-8-git-send-email-amit.shah@redhat.com> <1271222917-7803-9-git-send-email-amit.shah@redhat.com> <1271222917-7803-10-git-send-email-amit.shah@redhat.com> <1271222917-7803-11-git-send-email-amit.shah@redhat.com> <1271222917-7803-12-git-send-email-amit.shah@redhat.com> <1271222917-7803-13-git-send-email-amit.shah@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.18 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: qemu list , Amit Shah , Avi Kivity , Gerd Hoffmann , Juan Quintela Subject: [Qemu-devel] [PATCH v5 13/17] virtio-serial: Handle scatter-gather buffers for control messages X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Current control messages are small enough to not be split into multiple buffers but we could run into such a situation in the future or a malicious guest could cause such a situation. So handle the entire iov request for control messages. Also ensure the size of the control request is >= what we expect otherwise we risk accessing memory that we don't own. Signed-off-by: Amit Shah CC: Avi Kivity Reported-by: Avi Kivity --- hw/virtio-serial-bus.c | 31 ++++++++++++++++++++++++++++--- 1 files changed, 28 insertions(+), 3 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index a72b6b5..b8410c3 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -204,7 +204,7 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port) } /* Guest wants to notify us of some event */ -static void handle_control_message(VirtIOSerial *vser, void *buf) +static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len) { struct VirtIOSerialPort *port; struct virtio_console_control cpkt, *gcpkt; @@ -213,6 +213,11 @@ static void handle_control_message(VirtIOSerial *vser, void *buf) gcpkt = buf; + if (len < sizeof(cpkt)) { + /* The guest sent an invalid control packet */ + return; + } + cpkt.event = lduw_p(&gcpkt->event); cpkt.value = lduw_p(&gcpkt->value); @@ -306,13 +311,33 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq) { VirtQueueElement elem; VirtIOSerial *vser; + uint8_t *buf; + size_t len; vser = DO_UPCAST(VirtIOSerial, vdev, vdev); + len = 0; + buf = NULL; while (virtqueue_pop(vq, &elem)) { - handle_control_message(vser, elem.out_sg[0].iov_base); - virtqueue_push(vq, &elem, elem.out_sg[0].iov_len); + size_t cur_len, copied; + + cur_len = iov_size(elem.out_sg, elem.out_num); + /* + * Allocate a new buf only if we didn't have one previously or + * if the size of the buf differs + */ + if (cur_len > len) { + qemu_free(buf); + + buf = qemu_malloc(cur_len); + len = cur_len; + } + copied = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, len); + + handle_control_message(vser, buf, copied); + virtqueue_push(vq, &elem, copied); } + qemu_free(buf); virtio_notify(vdev, vq); }