linux-hardening - [PATCH] randstruct: disable Clang 15 support

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Message-Id: <20230208065133.220589-1-ebiggers@kernel.org>
Date:   Tue,  7 Feb 2023 22:51:33 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     linux-hardening@...r.kernel.org, Kees Cook <keescook@...omium.org>
Cc:     Bill Wendling <morbo@...gle.com>, llvm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] randstruct: disable Clang 15 support

From: Eric Biggers <ebiggers@...gle.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@...r.kernel.org
Signed-off-by: Eric Biggers <ebiggers@...gle.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