lib/test_stackinit: Fix static initializer test

The static initializer test got accidentally converted to a dynamic
initializer. Fix this and retain the giant padding hole without using
an aligned struct member.

Fixes: 50ceaa95 ("lib: Introduce test_stackinit module")
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: NKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210723221933.3431999-2-keescook@chromium.org

lib/test_stackinit.c

@@ -67,10 +67,10 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
 #define INIT_STRUCT_none		/**/
 #define INIT_STRUCT_zero		= { }
 #define INIT_STRUCT_static_partial	= { .two = 0, }
-#define INIT_STRUCT_static_all		= { .one = arg->one,		\
-					    .two = arg->two,		\
-					    .three = arg->three,	\
-					    .four = arg->four,		\
+#define INIT_STRUCT_static_all		= { .one = 0,			\
+					    .two = 0,			\
+					    .three = 0,			\
+					    .four = 0,			\
 					}
 #define INIT_STRUCT_dynamic_partial	= { .two = arg->two, }
 #define INIT_STRUCT_dynamic_all		= { .one = arg->one,		\
@@ -84,8 +84,7 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
 					var.one = 0;			\
 					var.two = 0;			\
 					var.three = 0;			\
-					memset(&var.four, 0,		\
-					       sizeof(var.four))
+					var.four = 0
 
 /*
  * @name: unique string name for the test
@@ -210,18 +209,13 @@ struct test_small_hole {
 	unsigned long four;
 };
 
-/* Try to trigger unhandled padding in a structure. */
-struct test_aligned {
-	u32 internal1;
-	u64 internal2;
-} __aligned(64);
-
+/* Trigger unhandled padding in a structure. */
 struct test_big_hole {
 	u8 one;
 	u8 two;
 	u8 three;
 	/* 61 byte padding hole here. */
-	struct test_aligned four;
+	u8 four __aligned(64);
 } __aligned(64);
 
 struct test_trailing_hole {