From patchwork Fri Mar 19 11:58:41 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 48143 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 C8094B7C48 for ; Fri, 19 Mar 2010 23:14:52 +1100 (EST) Received: from localhost ([127.0.0.1]:52006 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nsb1r-0003vk-HE for incoming@patchwork.ozlabs.org; Fri, 19 Mar 2010 08:10:15 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nsat9-0001BK-GE for qemu-devel@nongnu.org; Fri, 19 Mar 2010 08:01:16 -0400 Received: from [199.232.76.173] (port=35589 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nsat9-0001B0-40 for qemu-devel@nongnu.org; Fri, 19 Mar 2010 08:01:15 -0400 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Nsat4-0004ju-J5 for qemu-devel@nongnu.org; Fri, 19 Mar 2010 08:01:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62755) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Nsat2-0004iz-Fc for qemu-devel@nongnu.org; Fri, 19 Mar 2010 08:01:09 -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 o2JC0So9017612 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 19 Mar 2010 08:00:28 -0400 Received: from localhost (vpn-235-201.phx2.redhat.com [10.3.235.201]) by int-mx05.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o2JC0QTA028696; Fri, 19 Mar 2010 08:00:27 -0400 From: Amit Shah To: qemu-devel@nongnu.org Date: Fri, 19 Mar 2010 17:28:41 +0530 Message-Id: <1268999926-29560-5-git-send-email-amit.shah@redhat.com> In-Reply-To: <1268999926-29560-4-git-send-email-amit.shah@redhat.com> References: <1268999926-29560-1-git-send-email-amit.shah@redhat.com> <1268999926-29560-2-git-send-email-amit.shah@redhat.com> <1268999926-29560-3-git-send-email-amit.shah@redhat.com> <1268999926-29560-4-git-send-email-amit.shah@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.18 X-detected-operating-system: by monty-python.gnu.org: Genre and OS details not recognized. Cc: quintela@redhat.com, mst@redhat.com, virtualization@lists.linux-foundation.org, Avi Kivity , Amit Shah , kraxel@redhat.com Subject: [Qemu-devel] [PATCH 4/9] 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 | 43 ++++++++++++++++++++++++++++++++++++++++--- 1 files changed, 40 insertions(+), 3 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 830eb75..d5887ab 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -200,7 +200,7 @@ 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; @@ -208,6 +208,10 @@ static void handle_control_message(VirtIOSerial *vser, void *buf) size_t buffer_len; gcpkt = buf; + if (len < sizeof(cpkt)) { + /* The guest sent an invalid control packet */ + return; + } port = find_port_by_id(vser, ldl_p(&gcpkt->id)); if (!port) return; @@ -281,12 +285,45 @@ 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); + unsigned int i; + size_t cur_len, offset; + + cur_len = 0; + for (i = 0; i < elem.out_num; i++) { + cur_len += elem.out_sg[i].iov_len; + } + /* + * Allocate a new buf only if we didn't have one previously or + * if the size of the buf differs + */ + if (cur_len != len) { + if (len) { + qemu_free(buf); + } + buf = qemu_malloc(cur_len); + } + + offset = 0; + for (i = 0; i < elem.out_num; i++) { + memcpy(buf + offset, elem.out_sg[i].iov_base, + elem.out_sg[i].iov_len); + offset += elem.out_sg[i].iov_len; + } + len = cur_len; + + handle_control_message(vser, buf, len); + virtqueue_push(vq, &elem, len); + } + if (len) { + qemu_free(buf); } virtio_notify(vdev, vq); }