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 4F066C25B4E for ; Sun, 22 Jan 2023 15:06:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229864AbjAVPGi (ORCPT ); Sun, 22 Jan 2023 10:06:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230043AbjAVPGh (ORCPT ); Sun, 22 Jan 2023 10:06:37 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA1B91DBBA for ; Sun, 22 Jan 2023 07:06:36 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 685CE60C58 for ; Sun, 22 Jan 2023 15:06:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CFFFC433EF; Sun, 22 Jan 2023 15:06:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1674399995; bh=OqxWEtiTOn4kTu3mdysvMJoqky85DyyHjpgSTRcjVfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0QBXOM8n5M/6jb5W0DoyHBkMtrAX1Guf7Z+8quzPn/f8ibDAURKxFlWHdA9AGT/Ja Iu9xJro7d2fS7je5UhtWQ9ciHOf7Q5AnQmBr/p6z+aIIpvCgmyUTWgt93t0JwIKshK Kqq2cFE8rPPL/hhsPgIvHnsci3BGV8TYXd8lhx88= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, YingChi Long , Borislav Petkov , Nick Desaulniers , Nathan Chancellor Subject: [PATCH 4.14 25/25] x86/fpu: Use _Alignof to avoid undefined behavior in TYPE_ALIGN Date: Sun, 22 Jan 2023 16:04:25 +0100 Message-Id: <20230122150218.841731223@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230122150217.788215473@linuxfoundation.org> References: <20230122150217.788215473@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: YingChi Long commit 55228db2697c09abddcb9487c3d9fa5854a932cd upstream. WG14 N2350 specifies that it is an undefined behavior to have type definitions within offsetof", see https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm This specification is also part of C23. Therefore, replace the TYPE_ALIGN macro with the _Alignof builtin to avoid undefined behavior. (_Alignof itself is C11 and the kernel is built with -gnu11). ISO C11 _Alignof is subtly different from the GNU C extension __alignof__. Latter is the preferred alignment and _Alignof the minimal alignment. For long long on x86 these are 8 and 4 respectively. The macro TYPE_ALIGN's behavior matches _Alignof rather than __alignof__. [ bp: Massage commit message. ] Signed-off-by: YingChi Long Signed-off-by: Borislav Petkov Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220925153151.2467884-1-me@inclyc.cn Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/fpu/init.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -138,9 +138,6 @@ static void __init fpu__init_system_gene unsigned int fpu_kernel_xstate_size; EXPORT_SYMBOL_GPL(fpu_kernel_xstate_size); -/* Get alignment of the TYPE. */ -#define TYPE_ALIGN(TYPE) offsetof(struct { char x; TYPE test; }, test) - /* * Enforce that 'MEMBER' is the last field of 'TYPE'. * @@ -148,8 +145,8 @@ EXPORT_SYMBOL_GPL(fpu_kernel_xstate_size * because that's how C aligns structs. */ #define CHECK_MEMBER_AT_END_OF(TYPE, MEMBER) \ - BUILD_BUG_ON(sizeof(TYPE) != ALIGN(offsetofend(TYPE, MEMBER), \ - TYPE_ALIGN(TYPE))) + BUILD_BUG_ON(sizeof(TYPE) != \ + ALIGN(offsetofend(TYPE, MEMBER), _Alignof(TYPE))) /* * We append the 'struct fpu' to the task_struct: