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 02880C54FC6 for ; Tue, 3 Sep 2024 01:53:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6E5986B03E4; Mon, 2 Sep 2024 21:53:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 696008D00E7; Mon, 2 Sep 2024 21:53:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 536886B03E6; Mon, 2 Sep 2024 21:53:22 -0400 (EDT) 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 349086B03E4 for ; Mon, 2 Sep 2024 21:53:22 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B306040280 for ; Tue, 3 Sep 2024 01:53:21 +0000 (UTC) X-FDA: 82521754602.02.5F861FF Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) by imf12.hostedemail.com (Postfix) with ESMTP id D65D24000E for ; Tue, 3 Sep 2024 01:53:19 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=kvs1151T; spf=pass (imf12.hostedemail.com: domain of rientjes@google.com designates 209.85.214.171 as permitted sender) smtp.mailfrom=rientjes@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1725328352; a=rsa-sha256; cv=none; b=Ixt3CCFxJ34Aoax5dbM/ak/siJ8x5oy/krRVdJWrK1PSavmlFHWqEBPQe+Msmli0jalMs0 nlXCNJmJ/EE2YBF6EjubPqDZbSQqtnpGYrYmzD7V4t9QkR6mJbgfZnv8KzUhecq2pW49gX 1LvSeJ17W/WSmjWZOGNq7J7v5Q++AEE= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=kvs1151T; spf=pass (imf12.hostedemail.com: domain of rientjes@google.com designates 209.85.214.171 as permitted sender) smtp.mailfrom=rientjes@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1725328352; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Oa5rtkcqTKo2zYhIyQDpkUbrotmaYMsM7bl9Xg4sY14=; b=CbZReFfVspB4eoIiXe2ws3v9FjFB9mjkkxDjqCJo0cpABCvSfhkq+77+4ZTL5ZavyulxwC YU/zoS+58ZeBYMo7pZIuJ0j5h/L9LaVsOudzeS5bprJQbDNjpA8EdlG004Dwk8cmV3DGqf 4KtIJc54owCpsZvurkA60Y+ZhlJt2QI= Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-2056aa5cefcso302785ad.0 for ; Mon, 02 Sep 2024 18:53:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1725328398; x=1725933198; darn=kvack.org; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=Oa5rtkcqTKo2zYhIyQDpkUbrotmaYMsM7bl9Xg4sY14=; b=kvs1151TdZZo34ig9fzERyvKRJYxjtRmbYYaIQE1RRPm7GIROUDbBjWJfoG8fzPNH6 zPTsfOuJzoVQYA66ko9RIIf9e7piHaGiuKhIFpKvhvrKdUNmqtCdatyiXdzcJKNuee/G T8jT2/0JE7h0A2N5XbpHKn5WEr0gcMRNHRFeCTfEd58ibNlR+kdSNbaW7rk+XdhQa9P2 vdYQGDQqmycAk7B5sQ/ktfjDSl4cwpMbYRJCMuAT3i4e1yRswiRi6wsRzwYschAyt5u4 u1qwUfFgae/MkMID0RZ2ZG2ZFnkNb6KPPr6zRJ/h2ypBwWjFAIfosJycsJnNcl/XrKXt lzew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725328398; x=1725933198; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Oa5rtkcqTKo2zYhIyQDpkUbrotmaYMsM7bl9Xg4sY14=; b=RkB7RdNFuQ5XFJbCGuu7TpdosU500WjXAl3DWH6T1b1pmne8wxSSLBQzJoaJxa/XBf IcxKzuagzT0tIJ1ugklxDlm6mSkYYnRPco79ah7QdJHlk2NZkAntffTv/ANn22OyamAx LvLJRa0wOG/4FPNTrAEZ3DzzUYcC+7eMO+BN+RowvQyQzeqoAnpmsH2pYjUSb4+3cATo /g/9WMseFiaHkCbOVeMqxvAj6te61IMInz2Qt1xOzT8ire9SmlXLhpa7hmQ1li6nnA7J EYlg9MrbP0SwphPlszp3js/f4RI1cvOUZXm3wZNKiGIF9mOadbSenXo8bY7xQWi/BeeT pbyQ== X-Forwarded-Encrypted: i=1; AJvYcCWG5eF/f03Wwsy6ZTlecTYzpwwAPkeZ5HRrhnIZOcPNsiJNeN8nBVU3b6X19hAqYh3YbaV2SDe9EQ==@kvack.org X-Gm-Message-State: AOJu0Yxf3RO6nnJ9JEFkYESNbSCFYYHs0MjorV1xEcNd++2Et2EALXN+ o2PuDpQ7gcX5a9jlScSkyN012LksjF7u8utnBCohPL/aI16j4SglrdHEb1RjFg== X-Google-Smtp-Source: AGHT+IGDQJviICqG8bzc9DeFAVvSmJK6ShP9hGVeUCTgS+t0sDI+6Q3vyH4V+VJA5A7u6K8sZJldmg== X-Received: by 2002:a17:902:c947:b0:1fd:8c42:61ce with SMTP id d9443c01a7336-20549b895b1mr5165455ad.27.1725328398008; Mon, 02 Sep 2024 18:53:18 -0700 (PDT) Received: from [2620:0:1008:15:69a5:b87c:3c08:3343] ([2620:0:1008:15:69a5:b87c:3c08:3343]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-715e56d6ecasm7679373b3a.142.2024.09.02.18.53.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2024 18:53:17 -0700 (PDT) Date: Mon, 2 Sep 2024 18:53:16 -0700 (PDT) From: David Rientjes To: "Peng Fan (OSS)" cc: Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Feng Tang , "open list:SLAB ALLOCATOR" , open list , Peng Fan Subject: Re: [PATCH V2] mm, slub: avoid zeroing kmalloc redzone In-Reply-To: <20240829032911.2801669-1-peng.fan@oss.nxp.com> Message-ID: <889f1f51-4c57-6833-ab79-bcc9674c3e76@google.com> References: <20240829032911.2801669-1-peng.fan@oss.nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: noteiigmtae3z8omnyg675btyckgm1te X-Rspamd-Queue-Id: D65D24000E X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1725328399-610225 X-HE-Meta: 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 /jUVNKgX 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 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: On Thu, 29 Aug 2024, Peng Fan (OSS) wrote: > From: Peng Fan > > Since commit 946fa0dbf2d8 ("mm/slub: extend redzone check to extra > allocated kmalloc space than requested"), setting orig_size treats > the wasted space (object_size - orig_size) as a redzone. However with > init_on_free=1 we clear the full object->size, including the redzone. > > Additionally we clear the object metadata, including the stored orig_size, > making it zero, which makes check_object() treat the whole object as a > redzone. > > These issues lead to the following BUG report with "slub_debug=FUZ > init_on_free=1": > > [ 0.000000] ============================================================================= > [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten > [ 0.000000] ----------------------------------------------------------------------------- > [ 0.000000] > [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc > [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc > [ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) > [ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 > [ 0.000000] > [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ > [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 > [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) > [ 0.000000] Call trace: > [ 0.000000] dump_backtrace+0x90/0xe8 > [ 0.000000] show_stack+0x18/0x24 > [ 0.000000] dump_stack_lvl+0x74/0x8c > [ 0.000000] dump_stack+0x18/0x24 > [ 0.000000] print_trailer+0x150/0x218 > [ 0.000000] check_object+0xe4/0x454 > [ 0.000000] free_to_partial_list+0x2f8/0x5ec > > To address the issue, use orig_size to clear the used area. And restore > the value of orig_size after clear the remaining area. > > When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns > s->object_size. So when using memset to init the area, the size can simply > be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not > enabled. And orig_size can never be bigger than object_size. > > Fixes: 946fa0dbf2d8 ("mm/slub: extend redzone check to extra allocated kmalloc space than requested") > Reviewed-by: Feng Tang > Signed-off-by: Peng Fan Acked-by: David Rientjes