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 CD9C5E9A03B for ; Thu, 19 Feb 2026 07:57:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DFA456B0088; Thu, 19 Feb 2026 02:57:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DA7586B0089; Thu, 19 Feb 2026 02:57:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7C9D6B008A; Thu, 19 Feb 2026 02:57:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id B264D6B0088 for ; Thu, 19 Feb 2026 02:57:10 -0500 (EST) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6AF92160473 for ; Thu, 19 Feb 2026 07:57:10 +0000 (UTC) X-FDA: 84460450620.27.23BD7CE Received: from mail-wm1-f49.google.com (mail-wm1-f49.google.com [209.85.128.49]) by imf21.hostedemail.com (Postfix) with ESMTP id 8045C1C0006 for ; Thu, 19 Feb 2026 07:57:08 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linaro.org header.s=google header.b=T5RPnuw5; dmarc=pass (policy=none) header.from=linaro.org; spf=pass (imf21.hostedemail.com: domain of dan.carpenter@linaro.org designates 209.85.128.49 as permitted sender) smtp.mailfrom=dan.carpenter@linaro.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771487828; a=rsa-sha256; cv=none; b=W4Lh7R24ccJ4UgHWn4hv6zyDsdqw11WCTTOZIiqrVHglTIpCgwq/hodbIVQnivx4PlqaYk 4ELjMn6ePR06UMmRAN7t3O0qi78CH7/qycV2RoR0kfEKWGgm1jCYHZudMFoiOlNtfZSB7D fO4vYts0FoypB9COL3yhJAcDMApw5lU= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linaro.org header.s=google header.b=T5RPnuw5; dmarc=pass (policy=none) header.from=linaro.org; spf=pass (imf21.hostedemail.com: domain of dan.carpenter@linaro.org designates 209.85.128.49 as permitted sender) smtp.mailfrom=dan.carpenter@linaro.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771487828; 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=ee6rz3n4lRLIfzQydkYiBi8fGnwsN3AAWbuDK39dnaE=; b=t93TZRukRT8SP9uXURn/cnmE1QEymQhT0J0SARnTAyyCap5+wjSZlRAngQBS0qtpkGeX0g fkbDAPJr5dUiMkex7zL0+GZnXSmS6gmfnR0Pi5IGCnrsy4xPK7aIfpf86tseyC2rr2PCvC nKHU2KCeBVaMSo9vmIFDXox/4YZZeKk= Received: by mail-wm1-f49.google.com with SMTP id 5b1f17b1804b1-4806f3fc50bso7511445e9.0 for ; Wed, 18 Feb 2026 23:57:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1771487827; x=1772092627; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=ee6rz3n4lRLIfzQydkYiBi8fGnwsN3AAWbuDK39dnaE=; b=T5RPnuw5Ml0s94iiK9hjYg32YIwt2stb5Oks2FpgcCSDRVX0eaNtxFDGna22OOgjEr 845LRfdxX98B6DuuRfUw2XSFKscRKkGHzo5Dc4DVETa8Ptei87pO0PDII/p+mvUNEII7 HfORBwU86TjzAlaDr15zMyN0E34UvMA0y0hlUVbAmsCAdev5CADQYCEiG+xx5yx6OXMD S2Dey/qKGfSG2Ap9M/HGHMJR4/xSoTxukZjQE2mwJLrl8QPT4NgUNm9ssVP0s06yfg/N 6dZVu5ukB99ecobGUTsvuMRVSrFYPo+76x/8RuSWrbjPlomPtuPMmPK4Tg+dTsxH84cm uxfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771487827; x=1772092627; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ee6rz3n4lRLIfzQydkYiBi8fGnwsN3AAWbuDK39dnaE=; b=aXKS5RyzsHfE5fU8OsmTczySfbss1JmL/NcOYIM0jnkalVKZBoW1kzInKbLGgQKlq8 vJkzSx9qGPOcL/mDRL9Xy41/IHUt7nQFmpXtl3EqOoBlSX1Wi8/m2YWCu0hsKmVaFYuM Qt+AN+coS3HtkuRD9OjsIrYDSoATX60HPuX35+8N2R9tW+TM/idiYIGWllJYMmR5WUFS hm4FMG9ZMtzDFEoUjI+GbZw/3Ym4R2+LvbKy4D1rvunvkgRblFAoIFh9Py0ede/gWBmC +MtO6GGXdCuPIzBlMparNNxI52SuQmzPCpoiJPHiftxCI/BR6fP2pEdC54YNnvrVKkXU A0Dg== X-Forwarded-Encrypted: i=1; AJvYcCUQScC0tZFcCQWDHbYzZEvzCRlQMW3OkT/HLuJvNeEQfFSHqPVUFfdnVw1woPlQVpY/I7A3qi61jA==@kvack.org X-Gm-Message-State: AOJu0YyfFsoAARPUFGrW2yrVAyl7kZNa9VyIOQlGxEqAHFRV7MnhzhsS zM0s1TFNT5V7O0eT4CPIRQpl9nwjKA0OTCVeRCOWRuTb//KS03GId4lz/VL3+S3xGtg= X-Gm-Gg: AZuq6aLqeci+etQOZVxB72lmToEPe8Ka3ncMYT03oT9+tSq2LP8s8+oNLPs96oMz8A2 IQaj85HJ7RQNvBstZr5BwQ5ssvZQ5lPD5XaaQpUVPRJg1qErvWxvWk0HeqS8slP/5KMZlIoc/+p 56mPeb5sZEyrxa/HX2kOfBsfYIhcJy4ve4VZp2JrsmTXxpQpzQPN6Yi0pRobQsQ3hHKlBx+74Uh /a14CfX9KGRGxqaVoLdbH3y50s/zXHfke6408rTYpW5+herjJilGXK2Kid8gRIEeozpIaTfEy9c fuaNzl9yMziQpzKOwIpDAslhWSCnKmQMJ+SpunvxDT38ypjLHmDMBKzzMIgVldFcpTTWFWGenkC PRT4cgB96Ffe1P0rRJW+wMFSEQyorkJGhhe+oOpAmyc0aFEO5Do1PbJd+wh2dgegh9N9Bo5kk6y OjdMvoOpQeZVsIP13IibNitKEsZGaM X-Received: by 2002:a05:600c:698c:b0:477:5ad9:6df1 with SMTP id 5b1f17b1804b1-48379b932b7mr310004635e9.3.1771487826769; Wed, 18 Feb 2026 23:57:06 -0800 (PST) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4839f96967bsm15143135e9.3.2026.02.18.23.57.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Feb 2026 23:57:06 -0800 (PST) Date: Thu, 19 Feb 2026 10:57:03 +0300 From: Dan Carpenter To: Kees Cook Cc: Vlastimil Babka , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Gustavo A . R . Silva" , Bill Wendling , Justin Stitt , Jann Horn , Przemek Kitszel , Marco Elver , Linus Torvalds , Greg Kroah-Hartman , Sasha Levin , linux-mm@kvack.org, Randy Dunlap , Miguel Ojeda , Matthew Wilcox , John Hubbard , Joe Perches , Vegard Nossum , Harry Yoo , Nathan Chancellor , Peter Zijlstra , Nick Desaulniers , Jonathan Corbet , Jakub Kicinski , Yafang Shao , Tony Ambardar , Alexander Lobakin , Jan Hendrik Farr , Alexander Potapenko , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v6 1/5] slab: Introduce kmalloc_obj() and family Message-ID: References: <20251203233029.it.641-kees@kernel.org> <20251203233036.3212363-1-kees@kernel.org> <960729bb-0746-4709-a40c-2e254f963deb@suse.cz> <202601090928.5CFF95F@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202601090928.5CFF95F@keescook> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8045C1C0006 X-Stat-Signature: 5agkfcm8w9jmu5uu4w5gwi5c5m8dkaz9 X-HE-Tag: 1771487828-495536 X-HE-Meta: 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 7Xizw5u4 EtHdhnfJ64jp+02vMf7a0tPkR8ofa5BQ/3EszVfFVWifzuXqtkWLy5jZUqgiGZMtcqhv/fDDNotyVQrC1w7HeQeIDX6z9/GdG/a7PkKY2/+6LPYZHszF4A+T49PYuDicouxde1Et4q/RTzxRAVp6ditLazQCEGrqHllPj31xdgYX36Srl+Q9iSakJcyzgN22eXy2LY6uZrC3l7T1dnmep4fBJDD6G6CPDqzRavvYrCk/x3J626peuY7IspiDeTtpQPXiDmzEdaJU6CRgOl9h0MNKfAVBpiTEmJbMQorACmGhog97di0tYPpzibPdQyw32uzy70Sxw9EQxCq8qnZXJfUaqasPuJkOSiy9bYJvH+MpW8WalleGOq4KaP/vBpAUEn/au9Y7ME1rhTsnmvi4D2Xnk9GAsllL+YlBby40Gyn0P0RYKafcNCTQH07bCtuoG2UpG 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 Fri, Jan 09, 2026 at 09:31:03AM -0800, Kees Cook wrote: > On Thu, Jan 08, 2026 at 03:01:00PM +0100, Vlastimil Babka wrote: > > On 12/4/25 00:30, Kees Cook wrote: > > > [...] > > > +/** > > > + * __alloc_objs - Allocate objects of a given type using > > > + * @KMALLOC: which size-based kmalloc wrapper to allocate with. > > > + * @GFP: GFP flags for the allocation. > > > + * @TYPE: type to allocate space for. > > > + * @COUNT: how many @TYPE objects to allocate. > > > + * > > > + * Returns: Newly allocated pointer to (first) @TYPE of @COUNT-many > > > + * allocated @TYPE objects, or NULL on failure. > > > + */ > > > +#define __alloc_objs(KMALLOC, GFP, TYPE, COUNT) \ > > > +({ \ > > > + const size_t __obj_size = size_mul(sizeof(TYPE), COUNT); \ > > > > I assume with the hardcoded 1 for COUNT, this size_mul() will be eliminated > > by the compiler and not add unnecessary runtime overhead? Otherwise we > > should have two core #define variants. > > You're correct: the compiler completely collapses it with 0 runtime > overhead; a variant is not needed. > > > I also noted that the existing kmalloc_array() and kvmalloc_array() do > > check_mul_overflow() and return NULL silently on overflow. This AFAIU will > > make SIZE_MAX passed to the underlying kmalloc/kvmalloc and thus will cause > > a warning. That's IMHO a good thing. > > Right -- I prefer seeing the SIZE_MAX yelling from the allocator. Should > we change how k*malloc_array() behaves? Huh, yeah, it's weird to not get a stack trace if kmalloc() fails. On the other hand, if we're allocating SIZE_MAX, that is probably a user controlled size. Since we don't want people spamming dmesg, it should probably be WARN_ONCE(). regards, dan carpenter