From nobody Thu Nov 6 20:04:41 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.zoho.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 1488150297159863.2202692633738; Sun, 26 Feb 2017 15:04:57 -0800 (PST) Received: from localhost ([::1]:48852 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ci7s8-00074l-0J for importer@patchew.org; Sun, 26 Feb 2017 18:04:56 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50727) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ci7Xa-000697-UC for qemu-devel@nongnu.org; Sun, 26 Feb 2017 17:43:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ci7XX-0002z4-RR for qemu-devel@nongnu.org; Sun, 26 Feb 2017 17:43:42 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58977 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ci7XX-0002yv-Kj for qemu-devel@nongnu.org; Sun, 26 Feb 2017 17:43:39 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1QMcQep123786 for ; Sun, 26 Feb 2017 17:43:38 -0500 Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) by mx0a-001b2d01.pphosted.com with ESMTP id 28uqvksrgn-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sun, 26 Feb 2017 17:43:38 -0500 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 26 Feb 2017 17:43:38 -0500 Received: from d01dlp01.pok.ibm.com (9.56.250.166) by e18.ny.us.ibm.com (146.89.104.205) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Sun, 26 Feb 2017 17:43:35 -0500 Received: from b01cxnp22036.gho.pok.ibm.com (b01cxnp22036.gho.pok.ibm.com [9.57.198.26]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id 5F15C38C8039; Sun, 26 Feb 2017 17:43:36 -0500 (EST) Received: from b01ledav03.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v1QMhZSA52101342; Sun, 26 Feb 2017 22:43:35 GMT Received: from b01ledav03.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7565EB204D; Sun, 26 Feb 2017 17:43:33 -0500 (EST) Received: from [192.168.66.23] (unknown [9.164.183.34]) by b01ledav03.gho.pok.ibm.com (Postfix) with ESMTP id 3A005B2046; Sun, 26 Feb 2017 17:43:32 -0500 (EST) From: Greg Kurz To: qemu-devel@nongnu.org Date: Sun, 26 Feb 2017 23:43:32 +0100 In-Reply-To: <148814889214.28146.16915712763478774662.stgit@bahia> References: <148814889214.28146.16915712763478774662.stgit@bahia> User-Agent: StGit/0.17.1-20-gc0b1b-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17022622-0044-0000-0000-000002A867E5 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006689; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000204; SDB=6.00827424; UDB=6.00405424; IPR=6.00604941; BA=6.00005172; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014449; XFM=3.00000011; UTC=2017-02-26 22:43:38 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17022622-0045-0000-0000-000006D56F05 Message-Id: <148814901272.28146.1801619285977185367.stgit@bahia> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-02-26_11:, , 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=8.0.1-1612050000 definitions=main-1702260233 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PATCH v2 15/28] 9pfs: local: truncate: don't follow symlinks 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: Jann Horn , Prasad J Pandit , Greg Kurz , "Aneesh Kumar K.V" , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 The local_truncate() callback is vulnerable to symlink attacks because it calls truncate() which follows symbolic links in all path elements. This patch converts local_truncate() to rely on open_nofollow() and ftruncate() instead. This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz Reviewed-by: Stefan Hajnoczi --- hw/9pfs/9p-local.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c index e88426dfebe5..1d460a35aa7f 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -894,13 +894,14 @@ err_out: =20 static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size) { - char *buffer; - int ret; - char *path =3D fs_path->data; + int fd, ret; =20 - buffer =3D rpath(ctx, path); - ret =3D truncate(buffer, size); - g_free(buffer); + fd =3D local_open_nofollow(ctx, fs_path->data, O_WRONLY, 0); + if (fd =3D=3D -1) { + return -1; + } + ret =3D ftruncate(fd, size); + close_preserve_errno(fd); return ret; } =20