Received: by 2002:a05:6358:1087:b0:cb:c9d3:cd90 with SMTP id j7csp7359980rwi; Mon, 24 Oct 2022 13:31:02 -0700 (PDT) X-Google-Smtp-Source: AMsMyM5kn9LY8FNwJlKF+jEliQBgPrcAVVTGXbwxIFpHHFJVuBSGML9VifOVo98Q8XyEGL//8ZPW X-Received: by 2002:a17:907:2723:b0:78e:214b:e3c7 with SMTP id d3-20020a170907272300b0078e214be3c7mr30305841ejl.186.1666643462542; Mon, 24 Oct 2022 13:31:02 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1666643462; cv=none; d=google.com; s=arc-20160816; b=oUoooDJmhSky6wN7k5e635VsIb072MWaY3pczqTO7I0BHGf+SBHWHkPfie+ZoH4V9D e6RcLGiRbxOKhKXYsAUa923rHqOvXftnEvrLZtdeh8dcrwl1TDkq9foeFZcC3oLMPTaB uEUGjjCPKwwTdPK27hYH1/9lLsIFRr27dcYnAegANdP+8hkHLdJ713bllh8JOLyVDJNz w/bN4H+5QiZ13QjY+NBT/wNobHnYMfXpkkG+at1ca5uVW76Vfsqj8kho/ic6KvrbNudy RAKOWRFOWdk7XtFCFnb2qi/gpRh3/ERyZzwX+E/nbOqnlBy45raJPTymB42O3YgafsxX ILgQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=31nShqhFfxWJ7gMtaiLnwe5Fo0Zg/MiSxeUXRwvob6I=; b=KVmc+X+lO3q9hQcGjreOFjyMBCJOgTQZ6YEkbcF1L8pjCnQ/BGqZmwE3ojshWbuEBn chowsUZ1O6GU0CfCEmQMT7PSrO5lybWFlqD9Yr1VtQH+7qEJilcVIadUwOoCGIhZfcNH yxRF3kJ8z/OrP0Pr/2wIM+G3IqptwENTCQN4ufuRmLhq8x8Yz5W2sPxZhObxlXe2fQAX nPUgLJD1rzHVC7VHRTSyL1fokjFyo2MRVSCyNQfhu6nlnGanG3gqj8ndzouZzHcwV1GA uxGrB4/eEeExNvjJ20IQIy/E90xDCHnGgZVN3gwfQEaieKJPR5bqshiS1JE2lgtT1kuu 7x/w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="m5/mK342"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id b9-20020a170906708900b0078d8614e809si586999ejk.504.2022.10.24.13.30.37; Mon, 24 Oct 2022 13:31:02 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="m5/mK342"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233798AbiJXTxe (ORCPT + 99 others); Mon, 24 Oct 2022 15:53:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233675AbiJXTwP (ORCPT ); Mon, 24 Oct 2022 15:52:15 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A205635E0; Mon, 24 Oct 2022 11:17:24 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id E79CAB817BB; Mon, 24 Oct 2022 12:36:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49A3EC433D6; Mon, 24 Oct 2022 12:36:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666615007; bh=OZ4fCuISKgc6bcCsN5lRSFJ3XFy5d5qi6Tn0vsWgpB0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m5/mK3429Z8zM/SN7d0+K6R9hClOQm0bmFljWpDP3zOhJoEtufxqhkcETWlGMgXoS 1WElqWFt61tBaRFICXtJmVPmmTrP3CSoOu+MFoPio73gD8U9V5Ej1McA8dm+N5QxAb Am1i9IjW0PjntTcma0r/lKozU6uDdAJ1b4cTCzg4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Masahiro Yamada , llvm@lists.linux.dev, Will Deacon , Nick Desaulniers , Nathan Chancellor , Kees Cook Subject: [PATCH 5.15 086/530] hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO Date: Mon, 24 Oct 2022 13:27:10 +0200 Message-Id: <20221024113048.905560197@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024113044.976326639@linuxfoundation.org> References: <20221024113044.976326639@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kees Cook commit f02003c860d921171be4a27e2893766eb3bc6871 upstream. Currently under Clang, CC_HAS_AUTO_VAR_INIT_ZERO requires an extra -enable flag compared to CC_HAS_AUTO_VAR_INIT_PATTERN. GCC 12[1] will not, and will happily ignore the Clang-specific flag. However, its presence on the command-line is both cumbersome and confusing. Due to GCC's tolerant behavior, though, we can continue to use a single Kconfig cc-option test for the feature on both compilers, but then drop the Clang-specific option in the Makefile. In other words, this patch does not change anything other than making the compiler command line shorter once GCC supports -ftrivial-auto-var-init=zero. [1] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=a25e0b5e6ac8a77a71c229e0a7b744603365b0e9 Cc: Greg Kroah-Hartman Cc: Masahiro Yamada Cc: llvm@lists.linux.dev Fixes: dcb7c0b9461c ("hardening: Clarify Kconfig text for auto-var-init") Suggested-by: Will Deacon Link: https://lore.kernel.org/lkml/20210914102837.6172-1-will@kernel.org/ Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Acked-by: Will Deacon Signed-off-by: Kees Cook Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- Makefile | 6 +++--- security/Kconfig.hardening | 5 ++++- 2 files changed, 7 insertions(+), 4 deletions(-) --- a/Makefile +++ b/Makefile @@ -844,12 +844,12 @@ endif # Initialize all stack variables with a zero value. ifdef CONFIG_INIT_STACK_ALL_ZERO -# Future support for zero initialization is still being debated, see -# https://bugs.llvm.org/show_bug.cgi?id=45497. These flags are subject to being -# renamed or dropped. KBUILD_CFLAGS += -ftrivial-auto-var-init=zero +ifdef CONFIG_CC_IS_CLANG +# https://bugs.llvm.org/show_bug.cgi?id=45497 KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang endif +endif # While VLAs have been removed, GCC produces unreachable stack probes # for the randomize_kstack_offset feature. Disable it for all compilers. --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -23,13 +23,16 @@ config CC_HAS_AUTO_VAR_INIT_PATTERN def_bool $(cc-option,-ftrivial-auto-var-init=pattern) config CC_HAS_AUTO_VAR_INIT_ZERO + # GCC ignores the -enable flag, so we can test for the feature with + # a single invocation using the flag, but drop it as appropriate in + # the Makefile, depending on the presence of Clang. def_bool $(cc-option,-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang) choice prompt "Initialize kernel stack variables at function entry" default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS default INIT_STACK_ALL_PATTERN if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT_PATTERN - default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_PATTERN + default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_ZERO default INIT_STACK_NONE help This option enables initialization of stack variables at