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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 1A24BC4646D for ; Wed, 8 Aug 2018 09:24:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8B6921700 for ; Wed, 8 Aug 2018 09:24:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8B6921700 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727517AbeHHLno (ORCPT ); Wed, 8 Aug 2018 07:43:44 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51840 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727187AbeHHLno (ORCPT ); Wed, 8 Aug 2018 07:43:44 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EFBBF40241C3; Wed, 8 Aug 2018 09:24:53 +0000 (UTC) Received: from localhost (ovpn-204-54.brq.redhat.com [10.40.204.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3901A2166BA0; Wed, 8 Aug 2018 09:24:52 +0000 (UTC) Date: Wed, 8 Aug 2018 11:24:52 +0200 From: Stanislaw Gruszka To: Kees Cook Cc: Kalle Valo , "David S. Miller" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH wireless-drivers] mt76x0: Remove VLA usage Message-ID: <20180808092450.GA25772@redhat.com> References: <20180807225040.GA2164@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180807225040.GA2164@beast> User-Agent: Mutt/1.8.3 (2017-05-23) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 08 Aug 2018 09:24:54 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 08 Aug 2018 09:24:54 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'sgruszka@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 07, 2018 at 03:50:40PM -0700, Kees Cook wrote: > Even with "const" variables, the compiler will generate warnings about > VLA usage. In the quest to remove all VLAs from the kernel[1], this uses > a #define instead of a const to do the array sizing. > > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com > > Fixes: e87b5039511a ("mt76x0: eeprom files") > Signed-off-by: Kees Cook > --- > Please include this for the v4.19 merge window. The VLA was introduced > with the new source file (which I also note is missing a SPDX line), so I thought SPDX line is needed only if file has no license and eeprom.c file and other mt76x0 files have specified the license. Is SPDX still needed in that case ? > +#define MT_MAP_READS DIV_ROUND_UP(MT_EFUSE_USAGE_MAP_SIZE, 16) > static int > mt76x0_efuse_physical_size_check(struct mt76x0_dev *dev) > { > - const int map_reads = DIV_ROUND_UP(MT_EFUSE_USAGE_MAP_SIZE, 16); > - u8 data[map_reads * 16]; Why this is variable length array? DIV_ROUND_UP can not be calculated at compile time? But if so, macro do not change the situation either. Thanks Stanislaw