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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B85CC61DF7 for ; Fri, 24 Nov 2023 00:54:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B79B16B06A6; Thu, 23 Nov 2023 19:54:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B289E6B06A7; Thu, 23 Nov 2023 19:54:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97A756B06AA; Thu, 23 Nov 2023 19:54:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 88CC26B06A6 for ; Thu, 23 Nov 2023 19:54:57 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5CBD1120758 for ; Fri, 24 Nov 2023 00:54:57 +0000 (UTC) X-FDA: 81491028234.06.DA1C8EB Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.43]) by imf10.hostedemail.com (Postfix) with ESMTP id 88E3FC0006 for ; Fri, 24 Nov 2023 00:54:53 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=LCC96qqN; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf10.hostedemail.com: domain of feng.tang@intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=feng.tang@intel.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1700787294; a=rsa-sha256; cv=fail; b=gqtnOY29C3HIpUlEr6h4M2eWM/OCdJo1E38+CAUwLBZ3rb/1ExULHD1UfQ7a0HuRszCLhN LXjnOFIDLYOoInjUV/Plskg6xEQvgqSgTPEslLzQw8bWmJzgc/w6ZGQGoIqOR5v3vhYc8U mj2TpwsI/JWdjl+vBXbQ25sYFcM7xO4= ARC-Authentication-Results: i=2; imf10.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=LCC96qqN; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf10.hostedemail.com: domain of feng.tang@intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=feng.tang@intel.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1700787294; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0dqoKVhc5+sdR8QGU3tJAlLWkBNSGc9w4l0seMdfmm4=; b=QicK/Yvm/xvcAR2sqIMqBDbk/JmwgyQgmOwAn4/xIz0hbkfQmHibz5ykB7bjyLpasyz7mo dV7MjfHkAsrZidoQQrvxYuk9I2Gb0CIhUrynTmKvpvraStDwUnHVJxVVHxGK9oFjGGLkz1 u23fCchdRdESCwbEp/JwbGOrVEB2QRk= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1700787293; x=1732323293; h=date:from:to:cc:subject:message-id:references: content-transfer-encoding:in-reply-to:mime-version; bh=F2TRS/b4tNTqr4VJsiDl3YJIruPGaMWOX4jvDw5PzSk=; b=LCC96qqNkCL8Uv13dohy/efgk9Fntj7XloDeZjmICRSG4KjDK4vqcBMi s50z6iqD3hTm6frrMnkHKnwT+uCdiQxasnQc8aHWGzFXfIaap+YU2NnjQ lsiWrSrhFRc5Uhuk3I2LzNEUpoPINLof/d1XyHzMHT3D9NWh2k7x57rdT vFF2r3RbjxsKlzaO92lEA364GTB9k+0Q7qw2VlmbI9f/XDv5a6pafhyR4 25GovX6sA3Wi3H5yWixZ6ikxL5pXOGEbalBtJGsrDlGmW+dJccC/3XOis de1vONP7wKFi8KeIL+8KxNLV6M0Nejq103zdLaI66ztqQYLL2/xo7olAF g==; X-IronPort-AV: E=McAfee;i="6600,9927,10902"; a="478548135" X-IronPort-AV: E=Sophos;i="6.04,223,1695711600"; d="scan'208";a="478548135" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Nov 2023 16:54:50 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10902"; a="802070697" X-IronPort-AV: E=Sophos;i="6.04,223,1695711600"; d="scan'208";a="802070697" Received: from fmsmsx603.amr.corp.intel.com ([10.18.126.83]) by orsmga001.jf.intel.com with ESMTP/TLS/AES256-GCM-SHA384; 23 Nov 2023 16:54:45 -0800 Received: from fmsmsx610.amr.corp.intel.com (10.18.126.90) by fmsmsx603.amr.corp.intel.com (10.18.126.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Thu, 23 Nov 2023 16:54:44 -0800 Received: from fmsedg602.ED.cps.intel.com (10.1.192.136) by fmsmsx610.amr.corp.intel.com (10.18.126.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34 via Frontend Transport; Thu, 23 Nov 2023 16:54:44 -0800 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (104.47.59.169) by edgegateway.intel.com (192.55.55.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.34; Thu, 23 Nov 2023 16:54:44 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=EVNoBm7NclmN0tQ+BlHQjCQJdPr1dPLtX9yDYMdmKCecElsD+TsCzDseawHqbuZU67gw8PP3NBcujWotsOm5jFASuueHpu+Bwql4/tVljjRidNBHSWEZdgRCU6Qvke6Bo0FyLf9Wht5c0G02dMejVlFpWeghvX4wRrC+YAbXu13jMqtE3vtmxn+8d3n1o4oqTU5t/ZEPH4BJx9xtI/VDY9RcajjhHBmPNolvGEGse7Hw3PNsEIcciTnthKIKBdcaPKWQvHrj26eN0/AD0MjmqTOsgUZ1pOf1rWzAqa9mwnNeKTo4yd6o4uQ4PwdvSJOwPUfdNkceamOVOwPI9hAV5g== 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-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=0dqoKVhc5+sdR8QGU3tJAlLWkBNSGc9w4l0seMdfmm4=; b=fKW0iI35x00ZfzVkWngmKmgmXjOC57arzCAkicCLdHhirRQvCNEDZxFJD3VKz19KMsnoqKgj/PQpG2m+BGzHuHnl2YzJCsuEYU0LfiRK6qYgeygRiTzmcnx43V4Y3w5TL5aWiKd83hkMz3PxKTZheJSBXg1sdmMP32aMAXFFxhJ9tOu5lwHY/1sIf563dSLMzTylRVtUrsdWH5sh7ufrJxJnMKV5DSw7UK3xvrp4OH6/GoJGIxiqouoU2Xr9k2jcFnelTKtj9CZQOMaiRAM8Dhogy+HzJ68V67Tc3JIvQe0CGrkllu8cm+WbtOLoj/Uc+4qXmOkvP0HIGnyty7gx7w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Received: from MN0PR11MB6304.namprd11.prod.outlook.com (2603:10b6:208:3c0::7) by BL1PR11MB5477.namprd11.prod.outlook.com (2603:10b6:208:31f::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7025.20; Fri, 24 Nov 2023 00:54:42 +0000 Received: from MN0PR11MB6304.namprd11.prod.outlook.com ([fe80::24ce:9f48:bce:5ade]) by MN0PR11MB6304.namprd11.prod.outlook.com ([fe80::24ce:9f48:bce:5ade%7]) with mapi id 15.20.7025.020; Fri, 24 Nov 2023 00:54:42 +0000 Date: Fri, 24 Nov 2023 08:45:38 +0800 From: Feng Tang To: Andrey Konovalov CC: "andrey.konovalov@linux.dev" , Andrew Morton , Marco Elver , "Alexander Potapenko" , Dmitry Vyukov , "Vlastimil Babka" , "kasan-dev@googlegroups.com" , Evgenii Stepanov , "Oscar Salvador" , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Andrey Konovalov Subject: Re: [PATCH mm] slub, kasan: improve interaction of KASAN and slub_debug poisoning Message-ID: References: <20231122231202.121277-1-andrey.konovalov@linux.dev> Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: SGXP274CA0012.SGPP274.PROD.OUTLOOK.COM (2603:1096:4:b8::24) To MN0PR11MB6304.namprd11.prod.outlook.com (2603:10b6:208:3c0::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN0PR11MB6304:EE_|BL1PR11MB5477:EE_ X-MS-Office365-Filtering-Correlation-Id: 5ab128ee-7f5e-46a2-d561-08dbec87f16b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 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:MN0PR11MB6304.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(7916004)(366004)(376002)(396003)(136003)(39860400002)(346002)(230922051799003)(451199024)(64100799003)(186009)(1800799012)(316002)(6916009)(66476007)(66556008)(54906003)(66946007)(6512007)(53546011)(6506007)(6666004)(26005)(478600001)(38100700002)(6486002)(9686003)(33716001)(82960400001)(83380400001)(86362001)(7416002)(5660300002)(44832011)(2906002)(41300700001)(8936002)(8676002)(4326008);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?N2RZalZKYmhSbDFKcHZ6czR2TGRVTWdhQ3hnUStnVEp3eVhwK1pKOFp1U3pj?= =?utf-8?B?Q0pLT1h6RmJkLzIrVjE5ZFEyeVdXbkpRaHZzbXdhSGErWnBiT0ltRnczUG5r?= =?utf-8?B?eHNCS1JwTGNJN2ZUWTBCU0xyQ2t0WDNUVWhyVmozMXdpNXpWMkJlb3hSMDlm?= =?utf-8?B?NUw2akhYVDc4eFJLbS94d3lRRnJJRy9nSHdFeHpZTDVoeW93dnBxblNUZVAz?= =?utf-8?B?MmxkdmgvSFNuam55NHlITjM5MmxZZVF2M0ZVMHA1MklUOUErbDhmQ24rVkpT?= =?utf-8?B?WVJLYWNMSVFJeXhPekVnKzJnTW5NM2I0Z2JMWS9IbzdPQ0M0SytWVWtoMHc2?= =?utf-8?B?QTZsMjUrWUtDK3cyVmdVMVgzZEVGN3FUUXpwM0gwNHhYNTErM3dGNUt3N1Jy?= =?utf-8?B?UEJaSGNMeXI1dHZneVZqM0pmR1FqYlpRNEdSc0g5K2xSSDN0KzNCSDRTdXlV?= =?utf-8?B?SmNvMmwvQzdidnh1ay8xTUNIdFZNOVZzaXNOV2hhMk5YNmVITWsrNEdiVWxS?= =?utf-8?B?OXlhWDlpUVM1OGlWY0RCN3ArV0lHaFBSdmhuZEc5OVlLK0lEWEQ4akhJSDlF?= =?utf-8?B?aXZXQldtVDZWUXo5RnFvSjN2YmRSYmIzUU5tRDNSNE1ySGFTMWpjaWNMV09B?= =?utf-8?B?WXFGTVBiTkg5MWJlNmlWYlVUOXRmMTRoQkQ0UTRQY2NPUUkvU0JkWHlTczND?= =?utf-8?B?N0k2M3JPVTc1NTNNSnBxeXhhZ2FJM3VUOStLS0Y5SVNLVG83WFNCWFJUQlJp?= =?utf-8?B?cHMvbi9EaVlrZ082ZDduWlpIeGZOZklSWGw0M3RsWEZhczYzNjFWVUFjbUpt?= =?utf-8?B?b1hhVXZDc0F4SC9La1p5QnVvMHZRbDNNd21IYUZRYm15enBPZFhReGs2UTZW?= =?utf-8?B?TnMyU3ZKbGkrVk82SVNvVklNcEUyK0xHVlFFTEludS9jdDJvaFE3QVBqTnBT?= =?utf-8?B?dnlHM0VGVGtqSmd6azBMTnpDNFBvS2JzU3JlYVNlcENibDlwS0JhdjRjb3Vl?= =?utf-8?B?RFFGMGc1RVZwelNvNEFuV1VvckdCaXdzUmFkNExHQ0xlZWpRUlFDMXorTU1y?= =?utf-8?B?OEM1RkJHdGRMUGkyaHJ6N1c1STFlaVZzYTI1RWtyNFZzNzB2REdrb2VwRkNZ?= =?utf-8?B?TUpuTWFNbGtySFZkdlU3YnBxZzQ4NjhMSDEyL0toVkR1Yi9SSjVhZXZkVjVh?= =?utf-8?B?dWh0TUFTMWlpSHNiUHcxZk9sYnVMaFRRRkVyY2pYb3JVSVBtaHZzakdVRnFM?= =?utf-8?B?b3VIcFg2R3N6SmF1cUpkblJZMXhyMDN5UDg2MkRnSGFQd0pkNnVUQWFUY05P?= =?utf-8?B?bnJWRDQyM0FJSEhyOEppdDlaRVY0UW1rZGErQjV4bEk0MlBwVC9uQkxpNWF6?= =?utf-8?B?WFQxejdJcHIramhPL2FaNHFCazI0eTJhd21IR3dsMDJ2ZGJFWGEvdjVZRmls?= =?utf-8?B?dnlNclJBZ242TVU5MmM3Qld5ZVFaZDRYWHdrT1hNWHE0NEZtT29vamZqOGth?= =?utf-8?B?S2w5UGk3NURXeVJ3bCs2eFk0RUVhQlliTlBndU12cUI2RlZwVFhUeTFtVzFX?= =?utf-8?B?UlJEKzRJSjBVYWR0bXQrY245V1JvU3RGR09LUCtYUk43UFFST25BcFJUUjJ0?= =?utf-8?B?WVZjS1ppbUxDZ0hrK1dUaFNyQUpmOHRpNEhuWWVBbHJtakIyb3Zvb1RWYVk3?= =?utf-8?B?UlVDVngwaHEvNzdpNEd0YlEzdlBNajFWVk05ZVJtekU4ODRsL3A5WWhlTHlH?= =?utf-8?B?WVZpN1ppb3ZXSkZOWFFxbllhMStLbWMzNGxqankrNHhUMVN4amkrdWNLZnB2?= =?utf-8?B?czhSVTNDL3E1SUY1WnhKUTRMUjBuWHJ3MFRaakNZN25kNWVpOXBQVm9tNHNS?= =?utf-8?B?cnFSVzNMbzRNWUszSlpDUTh5YlVqbUx2Q2ZpY0FjM3JGWU5ETytIWlYxUS9O?= =?utf-8?B?ajlteVRRY3N3RXpNTnl2VlJkbDdQa1NOTWduWm1MRXppcmRNc2JPSmtleUtk?= =?utf-8?B?S2U2cHFvd3FTMzd2REdSLzdGSUJuTGZCY2w0bk9KNUZkTUtYcTBkS0xwTEM5?= =?utf-8?B?UitYU3dMQVE1QkxKZ1IvdUlYandQSkd2NUw0RUE4M3U4a0FScGh1cVE2QUx6?= =?utf-8?Q?0uxhnJEQ4e5Z8dyA/nfKgsyLl?= X-MS-Exchange-CrossTenant-Network-Message-Id: 5ab128ee-7f5e-46a2-d561-08dbec87f16b X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6304.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Nov 2023 00:54:42.3443 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: /nUxwmSeTmPbetsbrgFeBHPGSd2YXarcp+35n9B3OG+g5/znCo9IcZwNkIt69oQmfHzZu/Y8Oi/tlyOIH5T49g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR11MB5477 X-OriginatorOrg: intel.com X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 88E3FC0006 X-Stat-Signature: 33kk94fp4dmb85khsnzf8jbh6owh83ph X-HE-Tag: 1700787293-86433 X-HE-Meta: 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 Y8jZELlT 4IyQnlmEpkOCXLXBKSQ/tXP02vtIDiszKONnvWvF3q/PyKRH2X0HsaWoSl5uA3S38cemIzZbbbgzTh80Gt4wSVONL0taBGe+ET4m5Rdk0wh6J5JtwfBZNL6PznBdLCkTAQzbyflX83CraDUH9Da6/+m5kRR2GUMAFJkwKh7/QPxwmc1LKl8uyOZG3gvKrHxavayCoVeQ1+nBr7p9xeW9Lk/ZTwNkIYiGTNWym63PRMPmUamUH70dU4NkOH3mhEBT3PFo2ONI21mMpQ4TyOzMJH6aPpNPGXA0bszSfBfNMP+6Vn0Z01GJkHZ64RnfpGrT5V++CX/C5D53G7LW+Zui7eHdAsKo+8BqUab2lbUhT4/m5Ht5EQxRpQj3A10XNwzXWe89Ge0CWd/TMY7y2hTq6zf7bAjkvmP0v818gnQVlpXzn8X1p7s13Buldvu9CgSsg3Ru9D801YzmEYMI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Andrey, On Thu, Nov 23, 2023 at 05:12:08PM +0100, Andrey Konovalov wrote: > On Thu, Nov 23, 2023 at 7:35 AM Feng Tang wrote: > > > > Hi Feng, > > > > --- a/mm/slub.c > > > +++ b/mm/slub.c > > > @@ -870,20 +870,20 @@ static inline void set_orig_size(struct kmem_cache *s, > > > void *object, unsigned int orig_size) > > > { > > > void *p = kasan_reset_tag(object); > > > + unsigned int kasan_meta_size; > > > > > > if (!slub_debug_orig_size(s)) > > > return; > > > > > > -#ifdef CONFIG_KASAN_GENERIC > > > /* > > > - * KASAN could save its free meta data in object's data area at > > > - * offset 0, if the size is larger than 'orig_size', it will > > > - * overlap the data redzone in [orig_size+1, object_size], and > > > - * the check should be skipped. > > > + * KASAN can save its free meta data inside of the object at offset 0. > > > + * If this meta data size is larger than 'orig_size', it will overlap > > > + * the data redzone in [orig_size+1, object_size]. Thus, we adjust > > > + * 'orig_size' to be as at least as big as KASAN's meta data. > > > */ > > > - if (kasan_metadata_size(s, true) > orig_size) > > > - orig_size = s->object_size; > > > -#endif > > > + kasan_meta_size = kasan_metadata_size(s, true); > > > + if (kasan_meta_size > orig_size) > > > + orig_size = kasan_meta_size; > > > > 'orig_size' is to save the orignal request size for kmalloc object, > > and its main purpose is to detect the memory wastage of kmalloc > > objects, see commit 6edf2576a6cc "mm/slub: enable debugging memory > > wasting of kmalloc" > > > > Setting "orig_size = s->object_size" was to skip the wastage check > > and the redzone sanity check for this 'wasted space'. > > Yes, I get that. > > The point of my change was to allow slub_debug detecting overwrites in > the [kasan_meta_size, object_size) range when KASAN stores its free > meta in the [0, kasan_meta_size) range. If orig_size is set to > object_size, writes to that area will not be detected. I also thought > that using kasan_meta_size instead of object_size for orig_size might > give the reader better understanding of the memory layout. > > > So it's better not to set 'kasan_meta_size' to orig_size. > > I don't have a strong preference here: slub_debug and KASAN are not > really meant to be used together anyway. So if you prefer, I can > revert this change and keep using object_size as before. Thanks for the explanation! I got your point now. I'm fine with either way, as this change can help to enforce the redzone check for all kmalloc objects, while can make some debug wastage info less accurate. Thanks, Feng > > > And from the below code, IIUC, the orig_size is not used in fixing > > the boot problem found by Hyeonggon? > > No, this is a just a partially-related clean up. It just seemed > natural to include it into the fix, as it also touches the code around > a kasan_metadata_size call. > > Thanks!