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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98F66C54EE9 for ; Mon, 19 Sep 2022 14:51:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230051AbiISOvf (ORCPT ); Mon, 19 Sep 2022 10:51:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229570AbiISOvI (ORCPT ); Mon, 19 Sep 2022 10:51:08 -0400 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C97C810FDD; Mon, 19 Sep 2022 07:51:02 -0700 (PDT) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1oaI6u-0005ft-05; Mon, 19 Sep 2022 16:51:00 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id BAE67C12F2; Mon, 19 Sep 2022 16:49:36 +0200 (CEST) Date: Mon, 19 Sep 2022 16:49:36 +0200 From: Thomas Bogendoerfer To: Kees Cook Cc: Hauke Mehrtens , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , linux-mips@vger.kernel.org, Nathan Chancellor , Nick Desaulniers , llvm@lists.linux.dev, kernel test robot , Tom Rix , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *) Message-ID: <20220919144936.GE7674@alpha.franken.de> References: <20220907230556.73536-1-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220907230556.73536-1-keescook@chromium.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 07, 2022 at 04:05:56PM -0700, Kees Cook wrote: > Clang is especially sensitive about argument type matching when using > __overloaded functions (like memcmp(), etc). Help it see that function > pointers are just "void *". Avoids this error: > > arch/mips/bcm47xx/prom.c:89:8: error: no matching function for call to 'memcmp' > if (!memcmp(prom_init, prom_init + mem, 32)) > ^~~~~~ > include/linux/string.h:156:12: note: candidate function not viable: no known conversion from 'void (void)' to 'const void *' for 1st argument extern int memcmp(const void *,const void *,__kernel_size_t); > > Cc: Hauke Mehrtens > Cc: "Rafał Miłecki" > Cc: Thomas Bogendoerfer > Cc: linux-mips@vger.kernel.org > Cc: Nathan Chancellor > Cc: Nick Desaulniers > Cc: llvm@lists.linux.dev > Reported-by: kernel test robot > Link: https://lore.kernel.org/lkml/202209080652.sz2d68e5-lkp@intel.com > Signed-off-by: Kees Cook > --- > arch/mips/bcm47xx/prom.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/mips/bcm47xx/prom.c b/arch/mips/bcm47xx/prom.c > index ab203e66ba0d..eb5c04a24531 100644 > --- a/arch/mips/bcm47xx/prom.c > +++ b/arch/mips/bcm47xx/prom.c > @@ -86,7 +86,7 @@ static __init void prom_init_mem(void) > pr_debug("Assume 128MB RAM\n"); > break; > } > - if (!memcmp(prom_init, prom_init + mem, 32)) > + if (!memcmp((void *)prom_init, (void *)prom_init + mem, 32)) > break; > } > lowmem = mem; > -- > 2.34.1 applied to mips-next with the second memcmp(prom_init changed as well. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]