From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759573Ab3KMSjY (ORCPT ); Wed, 13 Nov 2013 13:39:24 -0500 Received: from smtp.outflux.net ([198.145.64.163]:58127 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756935Ab3KMSjR (ORCPT ); Wed, 13 Nov 2013 13:39:17 -0500 Date: Wed, 13 Nov 2013 10:39:13 -0800 From: Kees Cook To: Guenter Roeck Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] gcc4: Disable __compiletime_object_size for GCC 4.6+ Message-ID: <20131113183913.GK4994@outflux.net> References: <1365821348-7177-1-git-send-email-linux@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365821348-7177-1-git-send-email-linux@roeck-us.net> Organization: Outflux X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Guenter, On Fri, Apr 12, 2013 at 07:49:08PM -0700, Guenter Roeck wrote: > __builtin_object_size is known to be broken on gcc 4.6+. > See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48880 for details. > > This causes unnecssary build warnings and errors such as > > In function 'copy_from_user', inlined from 'sb16_copy_from_user' > at sound/oss/sb_audio.c:878:22: > arch/x86/include/asm/uaccess_32.h:211:26: error: call to 'copy_from_user_overflow' > declared with attribute error: copy_from_user() buffer size is not provably correct > make[3]: [sound/oss/sb_audio.o] Error 1 (ignored) > > Disable it where broken. Is there an alternative? This means that things like DEBUG_STRICT_USER_COPY_CHECKS are being rendered useless. I don't think this is _always_ broken, just under certain situations, right? -Kees > > Signed-off-by: Guenter Roeck > --- > include/linux/compiler-gcc4.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h > index 68b162d..842de22 100644 > --- a/include/linux/compiler-gcc4.h > +++ b/include/linux/compiler-gcc4.h > @@ -13,7 +13,7 @@ > #define __must_check __attribute__((warn_unused_result)) > #define __compiler_offsetof(a,b) __builtin_offsetof(a,b) > > -#if GCC_VERSION >= 40100 > +#if GCC_VERSION >= 40100 && GCC_VERSION < 40600 > # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) > #endif > > -- > 1.7.9.7 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kees Cook Chrome OS Security