From:   Eric Biggers <ebiggers@kernel.org>
To:     linux-hardening@vger.kernel.org, Kees Cook <keescook@chromium.org>
Cc:     Bill Wendling <morbo@google.com>, llvm@lists.linux.dev,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH] randstruct: disable Clang 15 support
Date:   Tue,  7 Feb 2023 22:51:33 -0800
Message-Id: <20230208065133.220589-1-ebiggers@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Eric Biggers <ebiggers@google.com>

The randstruct support released in Clang 15 is unsafe to use due to a
bug that can cause miscompilations: "-frandomize-layout-seed
inconsistently randomizes all-function-pointers structs"
(https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
on the Clang 16 release branch, so add a Clang version check.

Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 security/Kconfig.hardening | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 53baa95cb644f..0f295961e7736 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -281,6 +281,9 @@ endmenu
 
 config CC_HAS_RANDSTRUCT
 	def_bool $(cc-option,-frandomize-layout-seed-file=/dev/null)
+	# Randstruct was first added in Clang 15, but it isn't safe to use until
+	# Clang 16 due to https://github.com/llvm/llvm-project/issues/60349
+	depends on !CC_IS_CLANG || CLANG_VERSION >= 160000
 
 choice
 	prompt "Randomize layout of sensitive kernel structures"

base-commit: 4ec5183ec48656cec489c49f989c508b68b518e3
-- 
2.39.1