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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 243D2C61DD3 for ; Mon, 31 Aug 2026 10:06:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DC3296B008A; Mon, 31 Aug 2026 06:06:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D9B4A6B008C; Mon, 31 Aug 2026 06:06:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CB09A6B0092; Mon, 31 Aug 2026 06:06:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id A07026B008A for ; Mon, 31 Aug 2026 06:06:52 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id D3E22140462 for ; Mon, 31 Aug 2026 10:06:51 +0000 (UTC) X-FDA: 85161135822.03.6D3AAE3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf13.hostedemail.com (Postfix) with ESMTP id 1D3F620007 for ; Mon, 31 Aug 2026 10:06:49 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=DATBspxv; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of vbabka@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=vbabka@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788170810; 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=rTCa3x1+NLElVZAzpXp0yBo3FBCgVkxgyOn4AqetuYc=; b=OjR19qiqyfvjAeiilrbEY0z93R9oO4Fq87g17JEF4YASdwwcYxqnbARMYHAVFKw/nwEbg9 sF09/iMIL8PCd7GErW2o03/pMeLGYn/ftzsrKJDmuCVI16uQJ2hINXNlzllvMII63x69oR 3oJXlcxmRFRzvB1nGfYq1VmZa1Yt0BQ= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=DATBspxv; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of vbabka@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=vbabka@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788170810; b=swBmO4zTHiiVL4KgnWnffQg5R6j/yqK9ul4gTaK/TQqrXp+UIn4D7Y4eM0dsUTxjKUZ7Gl FX7CZ9jYU6rvBjFNk2t09PovzRxT0ejclsU1jAOjgJJw9yBPciU/+6ym91KbXkZ5B0fZ9G 81dym0fP19EOeiamymGMqLmEXeBBTME= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 69ECE6020C; Mon, 31 Aug 2026 10:06:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14D741F000E9; Mon, 31 Aug 2026 10:06:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788170809; bh=rTCa3x1+NLElVZAzpXp0yBo3FBCgVkxgyOn4AqetuYc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DATBspxvVs8agfsX5YhOCluh8TkwJHWyMCd4BSL1dTeYmEDfDsaCxZEJjDKrjKvOz +RF2NtLVrHEoSP3sc2RhlhoVs4Jo9HPzeIrhYcM8vAO2iDokd5nUHDsTlGtd5ePScf t76hAjtpxb7lZqcYvcun9GWkZpg+Ka+cC/yeXhBJUVRbpoVhrMnVuUuuBRXSbrnOT/ 4KqA0KoPyzsh+d5qhNIhDMGqzRXy5I6/qP6i2cWOUIoqEOb3O00cg2MbPu6go4uRut hSsH0kjGDEbsNwSnaemTYucOGQRHcltY6KgDJ0PUWzIMU0VmLUoZ07EEP1lOVeNagK fK9VMEfu6YK1g== Message-ID: <3d3c124b-04ae-49bf-8bbd-684b412f0a1c@kernel.org> Date: Mon, 31 Aug 2026 12:06:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] mm/slab_common: reject zero object_size before calculate_alignment Content-Language: en-US To: Longlong Xia , harry@kernel.org, akpm@linux-foundation.org Cc: hao.li@linux.dev, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia References: <20260826015506.3178758-1-xialonglong2025@163.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260826015506.3178758-1-xialonglong2025@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: s1umzbswk6x6f1yenwcggsz1m7951d9k X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1D3F620007 X-Rspam-User: X-HE-Tag: 1788170809-829182 X-HE-Meta: U2FsdGVkX18J+XNzcTC9QJ9k51dcWRV5n6CuzNJK1j6NQAsx2JbSXki2sw04bUF6lWIPqvB0QdXr00MlPXeUqQnseeeZWvaqvLJSTvzUcqm9I7tuPExsjiXwzgkcgk61ModLHmv1z5IJlsQkbn/WBnyyNIDoTN6eK4pBuTLuPysf43iLACUG3vRkPjm5TPGcE+DGsBfh2v8sPnV7QUaJNiTeITPkLwjBW4fHfGxp8SJDZT5Le68O+IQv6cHnds4622Tdd3/6evPTU1ywh8G8BKVguRLw8XSDMIz14Ca4YLDUdK5pMAg81GTQ/xZ1aLFPtRFwNQp9A8jf5dpuzkh1ou8cSGWzIb94bess1Vuh9Eb6UNFlEZSIcPjRw3N3U5A9+en80mfOrSwVnEHNxxl7EE0W7VlWJzoBURGdDiEH5GjMesTAFUpbRQO9c9SrYwonAR26ej4o1kt7YTQTTOM2/DmZQz1nkMsu/xJaIXSq+MOHW7jOk9q/oFWGY4wmPuud3F+IvYv8/57ZBkvBjdjlLhl+7LKeeeTLzBbo7u+sKNJT9ZETHVMZ/QBcOHj4PsoMHy+9agyCOsaz3XK5wXpqzaveVKwI2yghZd7DFb5Y/N8KzLr0VN8LghxHcaoBc6lh/jZpEr1ermWlRJU51YjMrE2eGyG5Mc4AMj23H6uenMks3/E4X0sUFnpli/wZsqj6fnhjXikLkHqtTnIOqT4RgRp4q4I0/GbPWkeBaUK4rCvGVX88v5zyNemSIxmevzdeQajYtgdvbrsZZKDdoksqP3tzSwmimQ+pMbMUhleCxgaQrZ/VQ9t0uSgG0/JPQ8eozDkiMJfmHjyNrH3wsb8Xi0zOlIOxAdMTS+yH6daPE8URiWGMjLPe5rsgEmbCIr1xqsCaEw+5EoiMfgOhhXVCTVwviK4n6T5yT2ppNLNWSI0z0K1qFpB4kRFKLX1+FZajrTJJObwt1LG7x8v3C1Z CMbhDrVl Ewf/sx2nlarBdMZnx7N5Sq6xXwqFq4vnys4mCjdjjaGOKs2/9UBWN3jpLB1oB2bBKJ9Hy8DvB0+ZbVOZ2ciX5LeUPWhJlBj+FQiD5pLQd8FEnFakeWXrRUYXtaGW0vNeKkgPN2b+Yqax91QZcMmL1/uF23Cv8oeyrIwcv72/DpzvA3h9dy7WbJOUN6OcYbCBN7btGDwaOO0Z+G2l7EIF/oFSOcvqm3fUwV9ZlWuZ2kl/r4Q01CcaE8FTgPfZJZPm4gBpoAg9gYZuX7jf/bk1qno774yf4rO2R//4N7xaWr/SDhYwvFzwLsIvvOXUfIf9Cp5VspaNnRUmc6OmKJEE4yXZ1TJYpCEpb4jha Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/26/26 03:55, Longlong Xia wrote: > From: Longlong Xia > > calculate_alignment() with SLAB_HWCACHE_ALIGN halves ralign in a > while (size <= ralign / 2) loop. When size is 0, ralign eventually > reaches 0 and the condition stays true indefinitely, hanging the > kernel. > > kmem_cache_sanity_check() rejected size > KMALLOC_MAX_SIZE but not > size == 0. Add !size to the check so a 0-size kmem_cache_create() is > caught on CONFIG_DEBUG_VM builds, where it can be diagnosed when it > surfaces. > > Suggested-by: Hao Li > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Longlong Xia Applied to mm/slab.git slab/for-next, thanks. I however support Harry's suggestion wrt (not) adressing theoretical issues like this going forward. > --- > Changes in v2: > - Drop the !object_size check in __kmem_cache_create_args() that v1 > added to the always-compiled path, and keep the guard only in the > debug-only kmem_cache_sanity_check(), as suggested by Hao Li. > > Link: https://lore.kernel.org/all/20260824092454.1693745-1-xialonglong2025@163.com/ > --- > mm/slab_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 95ddbab290d4..e205a99d85cf 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -102,7 +102,7 @@ static bool kmem_cache_is_duplicate_name(const char *name) > > static int kmem_cache_sanity_check(const char *name, unsigned int size) > { > - if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { > + if (!name || in_interrupt() || !size || size > KMALLOC_MAX_SIZE) { > pr_err("kmem_cache_create(%s) integrity check failed\n", name); > return -EINVAL; > }