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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,USER_AGENT_SANE_1 autolearn=no 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 72719C433DF for ; Tue, 19 May 2020 01:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35BEF20709 for ; Tue, 19 May 2020 01:37:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="JcpiRW9t"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="Ja0akDHB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728108AbgESBhH (ORCPT ); Mon, 18 May 2020 21:37:07 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:9822 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726532AbgESBhG (ORCPT ); Mon, 18 May 2020 21:37:06 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 04J1aprp017949; Mon, 18 May 2020 18:36:51 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=subject : to : cc : references : from : message-id : date : in-reply-to : content-type : content-transfer-encoding : mime-version; s=facebook; bh=kdkDRmBRw3AOdXl0cTNhLj6sfFXjj0a9j2kQ1tXWz9w=; b=JcpiRW9tnurdHbvWSEIH8U7wxYphafzPsFKPbXwhh7XOF30FuJ+qQdh++5Pun9hA7CXq 7yqsmmKbsnVs9c3fEVcP+VTEmsYkYF7aMqvkVV9BwYI04nFhG9S3tz8JK+/fY2qBbAlw jCLk6S7vNNlgiKPwawN2GMe30MYa/F+wI2c= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 31305aba7u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Mon, 18 May 2020 18:36:50 -0700 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (100.104.98.9) by o365-in.thefacebook.com (100.104.94.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Mon, 18 May 2020 18:36:29 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=LriHpLeeaQPFeHiiPxjiHqQmKRVF0wDzxkFdbaiF98eDHdhMPBFViJ6BlgOWJ+vMDSkqfe7Bt+6TGsBDdCVdxfPKVrWcevG625X/iByj0oBJYqvaHXEJPa1fD/bISSBWXvhBBCNt/iocMZ+f9ZM8g1G8Pd26SaftVbRN8wqeeJ5UiXDUXkU2JESUVLh9UsdySfiSvWogvharYrOxuAv0pHRBOabbuFMJ2Zm4zUfRzs0mo0JoHovdRg9etuMzZOaFvg49bkBpX+SxxT/NmptcH301fpe1ZTSS1sa9RdRtZE6ioHxxf0I/QT7PGylLEzt8nBrQXkiEFTpApcngaUK44A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=kdkDRmBRw3AOdXl0cTNhLj6sfFXjj0a9j2kQ1tXWz9w=; b=IZZzcCbJ0idLeCXRzEGe/RHdg+Llvw+qvu3m79aX82rrnYr5N2dqfFnJJ7IjPNmQXauWzTF2pj6TuyXbl53qhqU5UMB/nuKd8UXVEwJ8RlWhwW++qUGIW+7/hw/UbR2DsJ6qXXb0e4Eui/q3NQuFq6R6K48axQe2yWrJ89hYllF6M+z37/oYJI1FXEuaMeV8dPa/2/+bcBrC6CbV7v1QdheCfX1mSH/hc1Wspk53kHMj85HVRNqPI8VPuzglnm9x8KkChBHwIngsVh4u7oZprZdhTna+AxpIDseTr5fa/PObPyeT3PybHoe7GW/rYUPIZoNgBTtmcg139GUGJPbasQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=kdkDRmBRw3AOdXl0cTNhLj6sfFXjj0a9j2kQ1tXWz9w=; b=Ja0akDHBqJbY5RUP/qvCl1tXynVAwIezYrQA7CSafbfZsTOc233ZzfZtUOohZaMpEZ603PzxkgWKXbMeVv+17b8W797iYt2qtzBl6HIgyphh9NCO8gFSv4oh4pWqxOhlONM9jFz5vq14uoGw/J+wHbiBP2MeyMCrwg/4dvR0lQw= Authentication-Results: chromium.org; dkim=none (message not signed) header.d=none;chromium.org; dmarc=none action=none header.from=fb.com; Received: from BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) by BYAPR15MB3365.namprd15.prod.outlook.com (2603:10b6:a03:111::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3000.24; Tue, 19 May 2020 01:36:28 +0000 Received: from BYAPR15MB4088.namprd15.prod.outlook.com ([fe80::4922:9927:5d6c:5301]) by BYAPR15MB4088.namprd15.prod.outlook.com ([fe80::4922:9927:5d6c:5301%7]) with mapi id 15.20.3000.034; Tue, 19 May 2020 01:36:28 +0000 Subject: Re: UBSAN: array-index-out-of-bounds in kernel/bpf/arraymap.c:177 To: Andrii Nakryiko CC: Qian Cai , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Andrii Nakryiko , John Fastabend , KP Singh , Linux Netdev List , bpf , Linux Kernel Mailing List , clang-built-linux , Kees Cook References: <45f9ef5d-18e3-c92f-e7a9-1c6d6405e478@fb.com> From: Yonghong Song Message-ID: Date: Mon, 18 May 2020 18:36:26 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR05CA0015.namprd05.prod.outlook.com (2603:10b6:a03:c0::28) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from macbook-pro-52.local.dhcp.thefacebook.com (2620:10d:c090:400::5:f205) by BYAPR05CA0015.namprd05.prod.outlook.com (2603:10b6:a03:c0::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3021.12 via Frontend Transport; Tue, 19 May 2020 01:36:27 +0000 X-Originating-IP: [2620:10d:c090:400::5:f205] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 0239befe-64be-4502-b867-08d7fb950cf6 X-MS-TrafficTypeDiagnostic: BYAPR15MB3365: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-Forefront-PRVS: 040866B734 X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB4088.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(10001)(366004)(39860400002)(376002)(346002)(396003)(136003)(6486002)(2906002)(7416002)(6512007)(52116002)(53546011)(6506007)(5660300002)(31686004)(86362001)(6916009)(66476007)(8936002)(31696002)(66556008)(8676002)(66946007)(16526019)(186003)(54906003)(36756003)(478600001)(2616005)(316002)(4326008)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 0239befe-64be-4502-b867-08d7fb950cf6 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 May 2020 01:36:28.4098 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: SmmqETYodBihio51VHmhp2MfT16SusKiK8Z4sWvMWlVsTiJn1/667bWZSaDjqkij X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3365 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-18_11:2020-05-15,2020-05-18 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 bulkscore=0 spamscore=0 cotscore=-2147483648 clxscore=1015 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 suspectscore=27 phishscore=0 mlxscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005190013 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/18/20 6:30 PM, Andrii Nakryiko wrote: > On Mon, May 18, 2020 at 6:00 PM Yonghong Song wrote: >> >> >> >> On 5/18/20 5:25 PM, Andrii Nakryiko wrote: >>> On Mon, May 18, 2020 at 5:09 PM Qian Cai wrote: >>>> >>>> On Mon, May 18, 2020 at 7:55 PM Andrii Nakryiko >>>> wrote: >>>>> >>>>> On Sun, May 17, 2020 at 7:45 PM Qian Cai wrote: >>>>>> >>>>>> With Clang 9.0.1, >>>>>> >>>>>> return array->value + array->elem_size * (index & array->index_mask); >>>>>> >>>>>> but array->value is, >>>>>> >>>>>> char value[0] __aligned(8); >>>>> >>>>> This, and ptrs and pptrs, should be flexible arrays. But they are in a >>>>> union, and unions don't support flexible arrays. Putting each of them >>>>> into anonymous struct field also doesn't work: >>>>> >>>>> /data/users/andriin/linux/include/linux/bpf.h:820:18: error: flexible >>>>> array member in a struct with no named members >>>>> struct { void *ptrs[] __aligned(8); }; >>>>> >>>>> So it probably has to stay this way. Is there a way to silence UBSAN >>>>> for this particular case? >>>> >>>> I am not aware of any way to disable a particular function in UBSAN >>>> except for the whole file in kernel/bpf/Makefile, >>>> >>>> UBSAN_SANITIZE_arraymap.o := n >>>> >>>> If there is no better way to do it, I'll send a patch for it. >>> >>> >>> That's probably going to be too drastic, we still would want to >>> validate the rest of arraymap.c code, probably. Not sure, maybe >>> someone else has better ideas. >> >> Maybe something like below? >> >> struct bpf_array { >> struct bpf_map map; >> u32 elem_size; >> u32 index_mask; >> struct bpf_array_aux *aux; >> union { >> char value; >> void *ptrs; >> void __percpu *pptrs; >> } u[] __aligned(8); > > That will require wider code changes, and would look quite unnatural: > > array->u[whatever].pptrs > > instead of current > > array->pptrs[whatever] Right. There will be a tradeoff between to make it work vs. some code ugliness :-). BTW, I don't have a strong preference on how to solve this particular issue. > >> };