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 28974C32796 for ; Tue, 23 Aug 2022 08:22:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242719AbiHWIWK (ORCPT ); Tue, 23 Aug 2022 04:22:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243387AbiHWIVG (ORCPT ); Tue, 23 Aug 2022 04:21:06 -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 715C06EF18; Tue, 23 Aug 2022 01:12:28 -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 ams.source.kernel.org (Postfix) with ESMTPS id F3C29B81C39; Tue, 23 Aug 2022 08:12:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39ECAC433C1; Tue, 23 Aug 2022 08:12:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661242333; bh=MXJA4XP/6MA/jfd/hdNxnLp74hF+sgH6B5duzX+EI6I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v+r2MdEibRe4Lxvp1RfXkZNV/3eL5gi73hSmJV+EzPURHSIGjyTcMulC8Ss/VUTok guV7p1/s8rSj8lZ+1Npqa3Ri1cvwLxoI0b5QFBVMGR4GBnX922QGMEKes0j26wnnDZ xEtgM9Am9YeTyqa8UZfEmmLlQD22gkYUhs+1J9x8= 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 4.9 026/101] x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments Date: Tue, 23 Aug 2022 10:02:59 +0200 Message-Id: <20220823080035.574198870@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 ffcf9c5700e49c0aee42dcba9a12ba21338e8136 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: arch/x86/boot/pmjump.o: 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: arch/x86/boot/compressed/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 --- arch/x86/boot/Makefile | 2 +- arch/x86/boot/compressed/Makefile | 4 ++++ arch/x86/entry/vdso/Makefile | 2 +- 3 files changed, 6 insertions(+), 2 deletions(-) --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmli AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -m elf_i386 -T +LDFLAGS_setup.elf := -m elf_i386 -z noexecstack -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -54,6 +54,10 @@ else LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \ && echo "-z noreloc-overflow -pie --no-dynamic-linker") endif + +LDFLAGS += -z noexecstack +LDFLAGS += $(call ld-option,--no-warn-rwx-segments) + LDFLAGS_vmlinux := -T hostprogs-y := mkpiggy --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -168,7 +168,7 @@ quiet_cmd_vdso = VDSO $@ VDSO_LDFLAGS = -shared $(call ld-option, --hash-style=both) \ $(call ld-option, --build-id) $(call ld-option, --eh-frame-hdr) \ - -Bsymbolic + -Bsymbolic -z noexecstack GCOV_PROFILE := n #