From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 570E4ED8 for ; Sun, 16 Oct 2022 13:03:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E9B0C433D6; Sun, 16 Oct 2022 13:03:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1665925404; bh=AlMhoJR/gwF4fTaAgHcwWTWDmySoU0/SvBpsoS7+bOI=; h=Subject:To:Cc:From:Date:From; b=zLxFchi+PQ39oLimFeQ2qIyAl/fbJLI+8jCHNMo8s4AwmX9SX/HHG4rfc8nPNs7zd cwpacmK+ZI45BDfoUMw3ObzVjSva88vHfJ1AtCwVo1UIn1HjLLXb9a+bVhc2PEL583 aKEHgmMAp1Vh6TU+tFz/rVEjmJd3M3AYaHuNELwE= Subject: Patch "hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO" has been added to the 5.10-stable tree To: gregkh@linuxfoundation.org,keescook@chromium.org,llvm@lists.linux.dev,masahiroy@kernel.org,nathan@kernel.org,ndesaulniers@google.com,will@kernel.org Cc: From: Date: Sun, 16 Oct 2022 15:04:06 +0200 Message-ID: <16659254461882@kroah.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore This is a note to let you know that I've just added the patch titled hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hardening-avoid-harmless-clang-option-under-config_init_stack_all_zero.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From foo@baz Sun Oct 16 03:03:28 PM CEST 2022 From: Kees Cook Date: Tue, 14 Sep 2021 12:49:03 -0700 Subject: hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO 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 @@ -816,12 +816,12 @@ 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 DEBUG_CFLAGS := --- 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 Patches currently in stable-queue which might be from keescook@chromium.org are queue-5.10/hardening-avoid-harmless-clang-option-under-config_init_stack_all_zero.patch queue-5.10/hardening-remove-clang-s-enable-flag-for-ftrivial-auto-var-init-zero.patch queue-5.10/hardening-clarify-kconfig-text-for-auto-var-init.patch