From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A710C43441 for ; Wed, 14 Nov 2018 10:35:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D8DC2087A for ; Wed, 14 Nov 2018 10:35:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="gDKVMaQL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4D8DC2087A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732788AbeKNUiO (ORCPT ); Wed, 14 Nov 2018 15:38:14 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:53264 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727807AbeKNUiO (ORCPT ); Wed, 14 Nov 2018 15:38:14 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wAEAYISD180859; Wed, 14 Nov 2018 10:35:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=LQPGZ1ZZBUCslARdxXIXYIzsNi5Lbfm9NhZw89a0no4=; b=gDKVMaQLkJzcXfMirq2bxw73RwMVtsjdvXgyqHB9jodPl9UGpKD/lpgALrsOxsjTthaV kjojz1wBVak4oyzSBkz/+XGV8YiS0WLrgHbl5d37V9ampnB2fWzGD04Hk5/0Hu9LG/RQ /0eiSlPRC45hsBhi7fu7N8gitMJyuoEoBDIvkRKoEixmcnJjEI4LRZGbeY77o9KnW0ws lZou4kfVVGK96gwMq2bWmqTrmabWJTruUpe5wfUJZ/6IMXuCM4pxDJYISi6riyxa+HyK vdaK0FKWaqU9v0QbJg/hdFWwqMC/QNsVUi/QDmhx7LlOZ/95RTx0FpRwPZSSRAyv3gmF hA== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2nr7cs2jwr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 14 Nov 2018 10:35:28 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wAEAZRXk018137 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 14 Nov 2018 10:35:27 GMT Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id wAEAZQlQ000658; Wed, 14 Nov 2018 10:35:26 GMT Received: from [192.168.0.110] (/73.243.10.6) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 14 Nov 2018 02:35:26 -0800 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: [PATCH] mm/usercopy: Use memory range to be accessed for wraparound check From: William Kucharski In-Reply-To: <1542156686-12253-1-git-send-email-isaacm@codeaurora.org> Date: Wed, 14 Nov 2018 03:35:25 -0700 Cc: Kees Cook , crecklin@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, psodagud@codeaurora.org, tsoni@codeaurora.org, stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <1542156686-12253-1-git-send-email-isaacm@codeaurora.org> To: "Isaac J. Manjarres" X-Mailer: Apple Mail (2.3445.102.3) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9076 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=780 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1811140097 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 13, 2018, at 5:51 PM, Isaac J. Manjarres = wrote: >=20 > diff --git a/mm/usercopy.c b/mm/usercopy.c > index 852eb4e..0293645 100644 > --- a/mm/usercopy.c > +++ b/mm/usercopy.c > @@ -151,7 +151,7 @@ static inline void check_bogus_address(const = unsigned long ptr, unsigned long n, > bool to_user) > { > /* Reject if object wraps past end of memory. */ > - if (ptr + n < ptr) > + if (ptr + (n - 1) < ptr) > usercopy_abort("wrapped address", NULL, to_user, 0, ptr = + n); I'm being paranoid, but is it possible this routine could ever be passed = "n" set to zero? If so, it will erroneously abort indicating a wrapped address as (n - 1) = wraps to ULONG_MAX. Easily fixed via: if ((n !=3D 0) && (ptr + (n - 1) < ptr)) William Kucharski=