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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2294EC433E0 for ; Mon, 18 May 2020 19:09:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F29AE20657 for ; Mon, 18 May 2020 19:09:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726723AbgERTJV (ORCPT ); Mon, 18 May 2020 15:09:21 -0400 Received: from smtprelay0128.hostedemail.com ([216.40.44.128]:43052 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726703AbgERTJU (ORCPT ); Mon, 18 May 2020 15:09:20 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay01.hostedemail.com (Postfix) with ESMTP id 566B7100E7B45; Mon, 18 May 2020 19:09:19 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: grape47_8b57717f1c942 X-Filterd-Recvd-Size: 2379 Received: from XPS-9350.home (unknown [47.151.136.130]) (Authenticated sender: joe@perches.com) by omf16.hostedemail.com (Postfix) with ESMTPA; Mon, 18 May 2020 19:09:17 +0000 (UTC) Message-ID: Subject: Re: [PATCH] x86/uv/time: Replace one-element array and save heap space From: Joe Perches To: "Gustavo A. R. Silva" , Darren Hart , Andy Shevchenko , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "x86@kernel.org H. Peter Anvin" Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , Kees Cook Date: Mon, 18 May 2020 12:09:16 -0700 In-Reply-To: <20200518190114.GA7757@embeddedor> References: <20200518190114.GA7757@embeddedor> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-05-18 at 14:01 -0500, Gustavo A. R. Silva wrote: > The current codebase makes use of one-element arrays in the following > form: > > struct something { > int length; > u8 data[1]; > }; [] > This issue has been out there since 2009. > This issue was found with the help of Coccinelle and fixed _manually_. [] > diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c > index 7af31b245636..993a8ae6fdfb 100644 > --- a/arch/x86/platform/uv/uv_time.c > +++ b/arch/x86/platform/uv/uv_time.c > @@ -52,7 +52,7 @@ struct uv_rtc_timer_head { > struct { > int lcpu; /* systemwide logical cpu number */ > u64 expires; /* next timer expiration for this cpu */ > - } cpu[1]; > + } cpu[]; > }; > > /* > @@ -156,9 +156,8 @@ static __init int uv_rtc_allocate_timers(void) > struct uv_rtc_timer_head *head = blade_info[bid]; > > if (!head) { > - head = kmalloc_node(sizeof(struct uv_rtc_timer_head) + > - (uv_blade_nr_possible_cpus(bid) * > - 2 * sizeof(u64)), > + head = kmalloc_node(struct_size(head, cpu, > + uv_blade_nr_possible_cpus(bid)), It's probably safer to use kzalloc_node here as well. > GFP_KERNEL, nid); > if (!head) { > uv_rtc_deallocate_timers();