randstruct: disable Clang 15 support

commit 78f7a3fd6dc66cb788c21d7705977ed13c879351 upstream.

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>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Bill Wendling <morbo@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230208065133.220589-1-ebiggers@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 53baa95..0f29596 100644 (file)
--- 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"