Merge tag 'hardening-v6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - Disable __counted_by in Clang < 19.1.3 (Jan Hendrik Farr)

 - string_helpers: Silence output truncation warning (Bartosz
   Golaszewski)

 - compiler.h: Avoid needing BUILD_BUG_ON_ZERO() (Philipp Reisner)

 - MAINTAINERS: Add kernel hardening keywords __counted_by{_le|_be}
   (Thorsten Blum)

* tag 'hardening-v6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  Compiler Attributes: disable __counted_by for clang < 19.1.3
  compiler.h: Fix undefined BUILD_BUG_ON_ZERO()
  lib: string_helpers: silence snprintf() output truncation warning
  MAINTAINERS: Add kernel hardening keywords __counted_by{_le|_be}

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 0c8b9601e603..981cc3d7e3aa 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -330,6 +330,25 @@ struct ftrace_likely_data {
 #endif
 
 /*
+ * Optional: only supported since gcc >= 15
+ * Optional: only supported since clang >= 18
+ *
+ *   gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
+ * clang: https://github.com/llvm/llvm-project/pull/76348
+ *
+ * __bdos on clang < 19.1.2 can erroneously return 0:
+ * https://github.com/llvm/llvm-project/pull/110497
+ *
+ * __bdos on clang < 19.1.3 can be off by 4:
+ * https://github.com/llvm/llvm-project/pull/112636
+ */
+#ifdef CONFIG_CC_HAS_COUNTED_BY
+# define __counted_by(member)		__attribute__((__counted_by__(member)))
+#else
+# define __counted_by(member)
+#endif
+
+/*
  * Apply __counted_by() when the Endianness matches to increase test coverage.
  */
 #ifdef __LITTLE_ENDIAN