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 C00D3C32774 for ; Tue, 23 Aug 2022 08:18:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242279AbiHWISm (ORCPT ); Tue, 23 Aug 2022 04:18:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243092AbiHWIQf (ORCPT ); Tue, 23 Aug 2022 04:16:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B75B72BD2; Tue, 23 Aug 2022 01:11:28 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 534296129B; Tue, 23 Aug 2022 08:11:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 543C0C433D6; Tue, 23 Aug 2022 08:11:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661242287; bh=2+sQkRXsD0AeFSz1VPilz17J+suFYLIeRqzV6+TbAvw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YQDDrPT1s05JAD7z1qA3kt4WV5qkv16n115Ms5ZFh2OdpSKH13U6dClGuYu8FYo1y mQBrBHSU+hD7e5ZRbCC6P6BOLcsStuYTWRlp5KBbL7Y0esnQYy9231PFGFFT9/21Ij jkCoQ2iw3kO8rwlTvfEKRQ8A2AqYVNE6k6ROdOu8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fangrui Song , Nick Desaulniers , Linus Torvalds , Jens Axboe Subject: [PATCH 4.9 025/101] Makefile: link with -z noexecstack --no-warn-rwx-segments Date: Tue, 23 Aug 2022 10:02:58 +0200 Message-Id: <20220823080035.534613756@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080034.579196046@linuxfoundation.org> References: <20220823080034.579196046@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: Nick Desaulniers commit 0d362be5b14200b77ecc2127936a5ff82fbffe41 upstream. Users of GNU ld (BFD) from binutils 2.39+ will observe multiple instances of a new warning when linking kernels in the form: ld: warning: vmlinux: missing .note.GNU-stack section implies executable stack ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker ld: warning: vmlinux has a LOAD segment with RWX permissions Generally, we would like to avoid the stack being executable. Because there could be a need for the stack to be executable, assembler sources have to opt-in to this security feature via explicit creation of the .note.GNU-stack feature (which compilers create by default) or command line flag --noexecstack. Or we can simply tell the linker the production of such sections is irrelevant and to link the stack as --noexecstack. LLVM's LLD linker defaults to -z noexecstack, so this flag isn't strictly necessary when linking with LLD, only BFD, but it doesn't hurt to be explicit here for all linkers IMO. --no-warn-rwx-segments is currently BFD specific and only available in the current latest release, so it's wrapped in an ld-option check. While the kernel makes extensive usage of ELF sections, it doesn't use permissions from ELF segments. Link: https://lore.kernel.org/linux-block/3af4127a-f453-4cf7-f133-a181cce06f73@kernel.dk/ Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107 Link: https://github.com/llvm/llvm-project/issues/57009 Reported-and-tested-by: Jens Axboe Suggested-by: Fangrui Song Signed-off-by: Nick Desaulniers Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- Makefile | 3 +++ 1 file changed, 3 insertions(+) --- a/Makefile +++ b/Makefile @@ -870,6 +870,9 @@ ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATI LDFLAGS_vmlinux += $(call ld-option, --gc-sections,) endif +LDFLAGS += -z noexecstack +LDFLAGS += $(call ld-option,--no-warn-rwx-segments) + ifeq ($(CONFIG_STRIP_ASM_SYMS),y) LDFLAGS_vmlinux += $(call ld-option, -X,) endif