Merge tag 'hardening-v6.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening fix from Kees Cook:

 - stddef: make __struct_group() UAPI C++-friendly (Alexander Lobakin)

* tag 'hardening-v6.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  stddef: make __struct_group() UAPI C++-friendly

Author: torvalds

include/uapi/linux/stddef.h

@@ -8,6 +8,13 @@
 #define __always_inline inline
 #endif
 
+/* Not all C++ standards support type declarations inside an anonymous union */
+#ifndef __cplusplus
+#define __struct_group_tag(TAG)		TAG
+#else
+#define __struct_group_tag(TAG)
+#endif
+
 /**
  * __struct_group() - Create a mirrored named and anonyomous struct
  *
@@ -20,13 +27,13 @@
  * and size: one anonymous and one named. The former's members can be used
  * normally without sub-struct naming, and the latter can be used to
  * reason about the start, end, and size of the group of struct members.
- * The named struct can also be explicitly tagged for layer reuse, as well
- * as both having struct attributes appended.
+ * The named struct can also be explicitly tagged for layer reuse (C only),
+ * as well as both having struct attributes appended.
  */
 #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
 	union { \
 		struct { MEMBERS } ATTRS; \
-		struct TAG { MEMBERS } ATTRS NAME; \
+		struct __struct_group_tag(TAG) { MEMBERS } ATTRS NAME; \
 	} ATTRS
 
 #ifdef __cplusplus

tools/include/uapi/linux/stddef.h

@@ -8,6 +8,13 @@
 #define __always_inline __inline__
 #endif
 
+/* Not all C++ standards support type declarations inside an anonymous union */
+#ifndef __cplusplus
+#define __struct_group_tag(TAG)		TAG
+#else
+#define __struct_group_tag(TAG)
+#endif
+
 /**
  * __struct_group() - Create a mirrored named and anonyomous struct
  *
@@ -20,14 +27,14 @@
  * and size: one anonymous and one named. The former's members can be used
  * normally without sub-struct naming, and the latter can be used to
  * reason about the start, end, and size of the group of struct members.
- * The named struct can also be explicitly tagged for layer reuse, as well
- * as both having struct attributes appended.
+ * The named struct can also be explicitly tagged for layer reuse (C only),
+ * as well as both having struct attributes appended.
  */
 #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
 	union { \
 		struct { MEMBERS } ATTRS; \
-		struct TAG { MEMBERS } ATTRS NAME; \
-	}
+		struct __struct_group_tag(TAG) { MEMBERS } ATTRS NAME; \
+	} ATTRS
 
 /**
  * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union