Commit 86a9b125 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Kees Cook
Browse files

hardening: Require clang 20.1.0 for __counted_by 

After an innocuous change in -next that modified a structure that
contains __counted_by, clang-19 start crashing when building certain
files in drivers/gpu/drm/xe. When assertions are enabled, the more
descriptive failure is:

  clang: clang/lib/AST/RecordLayoutBuilder.cpp:3335: const ASTRecordLayout &clang::ASTContext::getASTRecordLayout(const RecordDecl *) const: Assertion `D && "Cannot get layout of forward declarations!"' failed.

According to a reverse bisect, a tangential change to the LLVM IR
generation phase of clang during the LLVM 20 development cycle [1]
resolves this problem. Bump the version of clang that enables
CONFIG_CC_HAS_COUNTED_BY to 20.1.0 to ensure that this issue cannot be
hit.

Link: https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489

 [1]
Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Reviewed-by: default avatarJustin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20250807-fix-counted_by-clang-19-v1-1-902c86c1d515@kernel.org


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent f05995cc

init/Kconfig

+5 −4
Original line number Diff line number Diff line
@@ -117,10 +117,11 @@ config CC_HAS_NO_PROFILE_FN_ATTR 


config CC_HAS_COUNTED_BY

	bool

	# clang needs to be at least 19.1.3 to avoid __bdos miscalculations

	# https://github.com/llvm/llvm-project/pull/110497

	# https://github.com/llvm/llvm-project/pull/112636

	default y if CC_IS_CLANG && CLANG_VERSION >= 190103

	# clang needs to be at least 20.1.0 to avoid potential crashes

	# when building structures that contain __counted_by

	# https://github.com/ClangBuiltLinux/linux/issues/2114

	# https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489

	default y if CC_IS_CLANG && CLANG_VERSION >= 200100

	# supported since gcc 15.1.0

	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896

	default y if CC_IS_GCC && GCC_VERSION >= 150100