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=-4.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, TVD_SUBJ_WIPE_DEBT,USER_AGENT_SANE_1 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 BEF6CC43332 for ; Tue, 2 Mar 2021 07:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 760F864D74 for ; Tue, 2 Mar 2021 07:12:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1575398AbhCBD4B (ORCPT ); Mon, 1 Mar 2021 22:56:01 -0500 Received: from gate.crashing.org ([63.228.1.57]:59311 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343967AbhCAWih (ORCPT ); Mon, 1 Mar 2021 17:38:37 -0500 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 121MVAHn003883; Mon, 1 Mar 2021 16:31:10 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 121MV9DG003882; Mon, 1 Mar 2021 16:31:09 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Mon, 1 Mar 2021 16:31:09 -0600 From: Segher Boessenkool To: Daniel Axtens Cc: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 01/15] powerpc/uaccess: Remove __get_user_allowed() and unsafe_op_wrap() Message-ID: <20210301223108.GE29191@gate.crashing.org> References: <87im6ao7ld.fsf@dja-thinkpad.axtens.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87im6ao7ld.fsf@dja-thinkpad.axtens.net> User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 02, 2021 at 09:02:54AM +1100, Daniel Axtens wrote: > Checkpatch does have one check that is relevant: > > CHECK: Macro argument reuse 'p' - possible side-effects? > #36: FILE: arch/powerpc/include/asm/uaccess.h:482: > +#define unsafe_get_user(x, p, e) do { \ > + if (unlikely(__get_user_nocheck((x), (p), sizeof(*(p)), false)))\ > + goto e; \ > +} while (0) sizeof (of something other than a VLA) does not evaluate its operand. The checkpatch warning is incorrect (well, it does say "possible" -- it just didn't find a possible problem here). You can write bla = sizeof *p++; and p is *not* incremented. Segher