From nobody Tue Dec 16 16:37:12 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1512590342963493.99119991271675; Wed, 6 Dec 2017 11:59:02 -0800 (PST) Received: from localhost ([::1]:57441 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMfqN-00018r-3B for importer@patchew.org; Wed, 06 Dec 2017 14:58:59 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49980) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMfCj-000100-6x for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:18:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMfCg-00012C-1t for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:18:01 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:47946) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMfCf-00010q-Nn for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:17:57 -0500 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB6JE45J043688 for ; Wed, 6 Dec 2017 14:17:56 -0500 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0a-001b2d01.pphosted.com with ESMTP id 2epmpw5emv-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 06 Dec 2017 14:17:56 -0500 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Wed, 6 Dec 2017 14:17:53 -0500 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id vB6JHr5C40763518; Wed, 6 Dec 2017 19:17:53 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ADD49AC04A; Wed, 6 Dec 2017 14:18:52 -0500 (EST) Received: from localhost (unknown [9.80.93.86]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP id 62DCFAC046; Wed, 6 Dec 2017 14:18:52 -0500 (EST) From: Michael Roth To: qemu-devel@nongnu.org Date: Wed, 6 Dec 2017 13:16:42 -0600 X-Mailer: git-send-email 2.11.0 In-Reply-To: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> References: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17120619-2213-0000-0000-00000246B564 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008161; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000244; SDB=6.00956379; UDB=6.00483442; IPR=6.00736416; BA=6.00005729; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018387; XFM=3.00000015; UTC=2017-12-06 19:17:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17120619-2214-0000-0000-0000585E2E0A Message-Id: <20171206191648.18208-50-mdroth@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-12-06_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712060273 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.156.1 Subject: [Qemu-devel] [PATCH 49/55] nbd/server: CVE-2017-15118 Stack smash on large export name 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: qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Eric Blake Introduced in commit f37708f6b8 (2.10). The NBD spec says a client can request export names up to 4096 bytes in length, even though they should not expect success on names longer than 256. However, qemu hard-codes the limit of 256, and fails to filter out a client that probes for a longer name; the result is a stack smash that can potentially give an attacker arbitrary control over the qemu process. The smash can be easily demonstrated with this client: $ qemu-io f raw nbd://localhost:10809/$(printf %3000d 1 | tr ' ' a) If the qemu NBD server binary (whether the standalone qemu-nbd, or the builtin server of QMP nbd-server-start) was compiled with -fstack-protector-strong, the ability to exploit the stack smash into arbitrary execution is a lot more difficult (but still theoretically possible to a determined attacker, perhaps in combination with other CVEs). Still, crashing a running qemu (and losing the VM) is bad enough, even if the attacker did not obtain full execution control. CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake (cherry picked from commit 51ae4f8455c9e32c54770c4ebc25bf86a8128183) Signed-off-by: Michael Roth --- nbd/server.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index b93cb88911..56aed3a735 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -393,6 +393,10 @@ static int nbd_negotiate_handle_info(NBDClient *client= , uint32_t length, msg =3D "name length is incorrect"; goto invalid; } + if (namelen >=3D sizeof(name)) { + msg =3D "name too long for qemu"; + goto invalid; + } if (nbd_read(client->ioc, name, namelen, errp) < 0) { return -EIO; } --=20 2.11.0