Merge tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - Update overflow helpers to ease refactoring of on-stack flex array
   instances (Gustavo A. R. Silva, Kees Cook)

 - lkdtm: Use SLAB_NO_MERGE instead of constructors (Harry Yoo)

 - Simplify CONFIG_CC_HAS_COUNTED_BY (Jan Hendrik Farr)

 - Disable u64 usercopy KUnit test on 32-bit SPARC (Thomas Weißschuh)

 - Add missed designated initializers now exposed by fixed randstruct
   (Nathan Chancellor, Kees Cook)

 - Document compilers versions for __builtin_dynamic_object_size

 - Remove ARM_SSP_PER_TASK GCC plugin

 - Fix GCC plugin randstruct, add selftests, and restore COMPILE_TEST
   builds

 - Kbuild: induce full rebuilds when dependencies change with GCC
   plugins, the Clang sanitizer .scl file, or the randstruct seed.

 - Kbuild: Switch from -Wvla to -Wvla-larger-than=1

 - Correct several __nonstring uses for -Wunterminated-string-initialization

* tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits)
  Revert "hardening: Disable GCC randstruct for COMPILE_TEST"
  lib/tests: randstruct: Add deep function pointer layout test
  lib/tests: Add randstruct KUnit test
  randstruct: gcc-plugin: Remove bogus void member
  net: qede: Initialize qede_ll_ops with designated initializer
  scsi: qedf: Use designated initializer for struct qed_fcoe_cb_ops
  md/bcache: Mark __nonstring look-up table
  integer-wrap: Force full rebuild when .scl file changes
  randstruct: Force full rebuild when seed changes
  gcc-plugins: Force full rebuild when plugins change
  kbuild: Switch from -Wvla to -Wvla-larger-than=1
  hardening: simplify CONFIG_CC_HAS_COUNTED_BY
  overflow: Fix direct struct member initialization in _DEFINE_FLEX()
  kunit/overflow: Add tests for STACK_FLEX_ARRAY_SIZE() helper
  overflow: Add STACK_FLEX_ARRAY_SIZE() helper
  input/joystick: magellan: Mark __nonstring look-up table const
  watchdog: exar: Shorten identity name to fit correctly
  mod_devicetable: Enlarge the maximum platform_device_id name length
  overflow: Clarify expectations for getting DEFINE_FLEX variable sizes
  compiler_types: Identify compiler versions for __builtin_dynamic_object_size
  ...

1 files changed, 20 insertions, 3 deletions

diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 0c7e3dcfe867..7b7be27ca113 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -396,7 +396,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
  * @name: Name for a variable to define.
  * @member: Name of the array member.
  * @count: Number of elements in the array; must be compile-time const.
- * @initializer: initializer expression (could be empty for no init).
+ * @initializer: Initializer expression (e.g., pass `= { }` at minimum).
  */
 #define _DEFINE_FLEX(type, name, member, count, initializer...)			\
 	_Static_assert(__builtin_constant_p(count),				\
@@ -404,7 +404,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
 	union {									\
 		u8 bytes[struct_size_t(type, member, count)];			\
 		type obj;							\
-	} name##_u initializer;							\
+	} name##_u = { .obj initializer };					\
 	type *name = (type *)&name##_u
 
 /**
@@ -419,6 +419,9 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
  * Define a zeroed, on-stack, instance of @type structure with a trailing
  * flexible array member.
  * Use __struct_size(@name) to get compile-time size of it afterwards.
+ * Use __member_size(@name->member) to get compile-time size of @name members.
+ * Use STACK_FLEX_ARRAY_SIZE(@name, @member) to get compile-time number of
+ * elements in array @member.
  */
 #define DEFINE_RAW_FLEX(type, name, member, count)	\
 	_DEFINE_FLEX(type, name, member, count, = {})
@@ -436,8 +439,22 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
  * Define a zeroed, on-stack, instance of @TYPE structure with a trailing
  * flexible array member.
  * Use __struct_size(@NAME) to get compile-time size of it afterwards.
+ * Use __member_size(@NAME->member) to get compile-time size of @NAME members.
+ * Use STACK_FLEX_ARRAY_SIZE(@name, @member) to get compile-time number of
+ * elements in array @member.
  */
 #define DEFINE_FLEX(TYPE, NAME, MEMBER, COUNTER, COUNT)	\
-	_DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .obj.COUNTER = COUNT, })
+	_DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .COUNTER = COUNT, })
+
+/**
+ * STACK_FLEX_ARRAY_SIZE() - helper macro for DEFINE_FLEX() family.
+ * Returns the number of elements in @array.
+ *
+ * @name: Name for a variable defined in DEFINE_RAW_FLEX()/DEFINE_FLEX().
+ * @array: Name of the array member.
+ */
+#define STACK_FLEX_ARRAY_SIZE(name, array)						\
+	(__member_size((name)->array) / sizeof(*(name)->array) +			\
+						__must_be_array((name)->array))
 
 #endif /* __LINUX_OVERFLOW_H */