From patchwork Wed Dec 6 16:49:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Chancellor X-Patchwork-Id: 13482040 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 E30C048CCE; Wed, 6 Dec 2023 16:49:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Gt49WcsQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35927C433C9; Wed, 6 Dec 2023 16:49:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701881397; bh=MIcvo5VKLktCV7iYkrFuhwma68u8LDf8q38/g/mtYpw=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Gt49WcsQsjZorSfQU8Hm9z6pyjA9z5Synz3BXnyWZScwzjBpHu0rS1eSVU1TvmcIF ibKSro8OcLDsjat9d7B9a+TnKHqyRMaO7JNok4TNYCGgujdG6FsFZGeqbeENMJqGo6 bHwbMWx5rUK0AntnCZe8hmRBepgU4c3kcGuCXTVGzG3zEpyyLMzJ03VPIXqr8HiVXx 6bCOQvYEZ8I2bNl+OskCPw3KT48VIicv0OAHFA+efymkmEJrX6gYVyf6+dwZaXieqI FfVyUOuLlb1se5lneErtOhfPzaJInRDgpe6KDfkSzAH+ubqf7MVOmWhfF+8lQNRY/x yK0hMIy/6w9Sg== From: Nathan Chancellor Date: Wed, 06 Dec 2023 09:49:47 -0700 Subject: [PATCH v2 2/2] kbuild: Enable -Wincompatible-function-pointer-types-strict in W=1 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231206-enable-wincompatible-function-pointer-types-strict-w-1-v2-2-91311b4c37b0@kernel.org> References: <20231206-enable-wincompatible-function-pointer-types-strict-w-1-v2-0-91311b4c37b0@kernel.org> In-Reply-To: <20231206-enable-wincompatible-function-pointer-types-strict-w-1-v2-0-91311b4c37b0@kernel.org> To: masahiroy@kernel.org Cc: ndesaulniers@google.com, morbo@google.com, justinstitt@google.com, keescook@chromium.org, samitolvanen@google.com, nicolas@fjasle.eu, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, patches@lists.linux.dev, Nathan Chancellor X-Mailer: b4 0.13-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2034; i=nathan@kernel.org; h=from:subject:message-id; bh=MIcvo5VKLktCV7iYkrFuhwma68u8LDf8q38/g/mtYpw=; b=owGbwMvMwCUmm602sfCA1DTG02pJDKkFy4xtpBWds09d/b/tY6nA1lpbZfNyzf2vzs9y5XwXd yzc3SKpo5SFQYyLQVZMkaX6sepxQ8M5ZxlvnJoEM4eVCWQIAxenAExkYRkjw9s/pqynFsQUdR96 IVU4IenIFWMWD31Ll4Bvsw8aPVfSU2f4X8jxJv7zuVrNv/39TYHdEQU9BZ4HuVxz3Pj1D7K661X xAgA= X-Developer-Key: i=nathan@kernel.org; a=openpgp; fpr=2437CB76E544CB6AB3D9DFD399739260CB6CB716 -Wincompatible-function-pointer-types-strict aims to catch clang kernel Control Flow Integrity (kCFI) violations at build time (rather than run time) by validating function pointer assignments against the expected prototype, similar to the existing -Wincompatible-function-pointer-types that is considered a hard error in the kernel. The -strict variant requires the types to match exactly, as opposed to just matching in terms of ABI compatibility. This is primarily visible with int/unsigned int in lieu of enum types or vice versa. The tree is not completely clean, so this warning cannot currently be enabled unconditionally. However, there are only warnings in one subsystem ('drivers/counter'), so it is really close. In order to benefit from CI infrastructure that tests with W=1, enable this warning at that level, so that new instances have a chance of being caught and fixed during development. This should eventually be a hard error in a similar manner as Wincompatible-function-pointer-types but some subsystems test with W=1 + CONFIG_WERROR=n, so it would be rude to break their builds when they do not care about warnings outside of their subsystem. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Reviewed-by: Kees Cook --- scripts/Makefile.extrawarn | 1 + 1 file changed, 1 insertion(+) diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 3f94915fab37..1452dd874a07 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -99,6 +99,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow) KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation) KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow) KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation) +KBUILD_CFLAGS += $(call cc-option, -Wincompatible-function-pointer-types-strict) KBUILD_CPPFLAGS += -Wundef KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1