From patchwork Fri Sep 30 15:12:58 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kurz X-Patchwork-Id: 9358535 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BED996077B for ; Fri, 30 Sep 2016 15:21:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B064E2A0A9 for ; Fri, 30 Sep 2016 15:21:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A524D2A0AC; Fri, 30 Sep 2016 15:21:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1CE512A0A9 for ; Fri, 30 Sep 2016 15:21:56 +0000 (UTC) Received: from localhost ([::1]:45208 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpzdL-0002lr-6t for patchwork-qemu-devel@patchwork.kernel.org; Fri, 30 Sep 2016 11:21:55 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53800) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpzUu-00044R-Ku for qemu-devel@nongnu.org; Fri, 30 Sep 2016 11:13:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpzUp-0004Od-G6 for qemu-devel@nongnu.org; Fri, 30 Sep 2016 11:13:12 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:57955 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpzUp-0004OH-Ac for qemu-devel@nongnu.org; Fri, 30 Sep 2016 11:13:07 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u8UF7xJB133549 for ; Fri, 30 Sep 2016 11:13:07 -0400 Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) by mx0b-001b2d01.pphosted.com with ESMTP id 25sr8rewvt-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 30 Sep 2016 11:13:06 -0400 Received: from localhost by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 30 Sep 2016 09:13:02 -0600 Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 444FC19D8047; Fri, 30 Sep 2016 09:12:30 -0600 (MDT) Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u8UFD28o12779822; Fri, 30 Sep 2016 08:13:02 -0700 Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3595178043; Fri, 30 Sep 2016 09:13:02 -0600 (MDT) Received: from [192.168.66.108] (unknown [9.164.139.88]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP id ED1E178037; Fri, 30 Sep 2016 09:12:59 -0600 (MDT) From: Greg Kurz To: qemu-devel@nongnu.org Date: Fri, 30 Sep 2016 17:12:58 +0200 In-Reply-To: <147524835229.953.16853431367911587573.stgit@bahia> References: <147524835229.953.16853431367911587573.stgit@bahia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16093015-8235-0000-0000-0000094EFE36 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00005830; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000186; SDB=6.00763113; UDB=6.00363859; IPR=6.00538276; BA=6.00004775; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00012833; XFM=3.00000011; UTC=2016-09-30 15:13:05 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16093015-8236-0000-0000-00003546E289 Message-Id: <147524837881.953.14115293542666286821.stgit@bahia> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-09-30_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=3 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609280000 definitions=main-1609300276 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PATCH v4 3/9] virtio-9p: handle handle_9p_output() error X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "Michael S. Tsirkin" , Jason Wang , Greg Kurz , Max Reitz , "Aneesh Kumar K.V" , Stefan Hajnoczi , Cornelia Huck , Paolo Bonzini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP A broken guest may send a request without providing buffers for the reply or for the request itself, and virtqueue_pop() will return an element with either in_num == 0 or out_num == 0. All 9P requests are expected to start with the following 7-byte header: uint32_t size_le; uint8_t id; uint16_t tag_le; If iov_to_buf() fails to return these 7 bytes, then something is wrong in the guest. In both cases, it is wrong to crash QEMU, since the root cause lies in the guest. This patch hence does the following: - keep the check of in_num since pdu_complete() assumes it has enough space to store the reply and we will send something broken to the guest - let iov_to_buf() handle out_num == 0, since it will return 0 just like if the guest had provided an zero-sized buffer. - call virtio_error() to inform the guest that the device is now broken, instead of aborting - detach the request from the virtqueue and free it Signed-off-by: Greg Kurz Reviewed-by: Stefan Hajnoczi --- v4: - added Stefan's R-b tag --- hw/9pfs/virtio-9p-device.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c index e7ea0e45f3dd..a338f6400264 100644 --- a/hw/9pfs/virtio-9p-device.c +++ b/hw/9pfs/virtio-9p-device.c @@ -41,6 +41,7 @@ static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq) V9fsState *s = &v->state; V9fsPDU *pdu; ssize_t len; + VirtQueueElement *elem; while ((pdu = pdu_alloc(s))) { struct { @@ -48,21 +49,28 @@ static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq) uint8_t id; uint16_t tag_le; } QEMU_PACKED out; - VirtQueueElement *elem; elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); if (!elem) { - pdu_free(pdu); - break; + goto out_free_pdu; } - BUG_ON(elem->out_num == 0 || elem->in_num == 0); + if (elem->in_num == 0) { + virtio_error(vdev, + "The guest sent a VirtFS request without space for " + "the reply"); + goto out_free_req; + } QEMU_BUILD_BUG_ON(sizeof(out) != 7); v->elems[pdu->idx] = elem; len = iov_to_buf(elem->out_sg, elem->out_num, 0, &out, sizeof(out)); - BUG_ON(len != sizeof(out)); + if (len != sizeof(out)) { + virtio_error(vdev, "The guest sent a malformed VirtFS request: " + "header size is %zd, should be 7", len); + goto out_free_req; + } pdu->size = le32_to_cpu(out.size_le); @@ -72,6 +80,14 @@ static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq) qemu_co_queue_init(&pdu->complete); pdu_submit(pdu); } + + return; + +out_free_req: + virtqueue_detach_element(vq, elem, 0); + g_free(elem); +out_free_pdu: + pdu_free(pdu); } static uint64_t virtio_9p_get_features(VirtIODevice *vdev, uint64_t features,