Commit a8fc576d authored by Kees Cook's avatar Kees Cook
Browse files

lib/test_stackinit: Add assigned initializers 



Add whole-variable assignments of cast static initializers. These appear
to currently behave like the direct initializers, but best to check them
too. For example:

	struct test_big_hole var;
	var = (struct test_big_hole){
		.one = arg->one,
		.two= arg->two,
		.three = arg->three,
		.four = arg->four };

Additionally adds a test for whole-object assignment, which is expected
to fail since it usually falls back to a memcpy():

	var = *arg;

Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/CAK8P3a20SEoYCrp3jOK32oZc9OkiPv+1KTjNZ2GxLbHpY4WexQ@mail.gmail.com


Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210723221933.3431999-4-keescook@chromium.org
parent 1e2cd308

lib/test_stackinit.c

+114 −55
Original line number Diff line number Diff line
@@ -95,6 +95,10 @@ static bool range_contains(char *haystack_start, size_t haystack_size, 
	return false;

}



/* Whether the test is expected to fail. */

#define WANT_SUCCESS				0

#define XFAIL					1



#define DO_NOTHING_TYPE_SCALAR(var_type)	var_type

#define DO_NOTHING_TYPE_STRING(var_type)	void

#define DO_NOTHING_TYPE_STRUCT(var_type)	void
@@ -120,34 +124,74 @@ static bool range_contains(char *haystack_start, size_t haystack_size, 
#define INIT_CLONE_STRING		[FILL_SIZE_STRING]

#define INIT_CLONE_STRUCT		/**/



#define INIT_SCALAR_none		/**/

#define INIT_SCALAR_zero		= 0

#define ZERO_CLONE_SCALAR(zero)		memset(&(zero), 0x00, sizeof(zero))

#define ZERO_CLONE_STRING(zero)		memset(&(zero), 0x00, sizeof(zero))

/*

 * For the struct, intentionally poison padding to see if it gets

 * copied out in direct assignments.

 * */

#define ZERO_CLONE_STRUCT(zero)				\

	do {						\

		memset(&(zero), 0xFF, sizeof(zero));	\

		zero.one = 0;				\

		zero.two = 0;				\

		zero.three = 0;				\

		zero.four = 0;				\

	} while (0)



#define INIT_SCALAR_none(var_type)	/**/

#define INIT_SCALAR_zero(var_type)	= 0



#define INIT_STRING_none		[FILL_SIZE_STRING] /**/

#define INIT_STRING_zero		[FILL_SIZE_STRING] = { }

#define INIT_STRING_none(var_type)	[FILL_SIZE_STRING] /**/

#define INIT_STRING_zero(var_type)	[FILL_SIZE_STRING] = { }



#define INIT_STRUCT_none		/**/

#define INIT_STRUCT_zero		= { }

#define INIT_STRUCT_static_partial	= { .two = 0, }

#define INIT_STRUCT_static_all		= { .one = 0,			\

#define INIT_STRUCT_none(var_type)	/**/

#define INIT_STRUCT_zero(var_type)	= { }





#define __static_partial		{ .two = 0, }

#define __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,		\

#define __dynamic_partial		{ .two = arg->two, }

#define __dynamic_all			{ .one = arg->one,		\

					  .two = arg->two,		\

					  .three = arg->three,		\

					  .four = arg->four,		\

					}

#define INIT_STRUCT_runtime_partial	;				\

					var.two = 0

#define INIT_STRUCT_runtime_all		;				\

					var.one = 0;			\

#define __runtime_partial		var.two = 0

#define __runtime_all			var.one = 0;			\

					var.two = 0;			\

					var.three = 0;			\

					var.four = 0



#define INIT_STRUCT_static_partial(var_type)				\

					= __static_partial

#define INIT_STRUCT_static_all(var_type)				\

					= __static_all

#define INIT_STRUCT_dynamic_partial(var_type)				\

					= __dynamic_partial

#define INIT_STRUCT_dynamic_all(var_type)				\

					= __dynamic_all

#define INIT_STRUCT_runtime_partial(var_type)				\

					; __runtime_partial

#define INIT_STRUCT_runtime_all(var_type)				\

					; __runtime_all



#define INIT_STRUCT_assigned_static_partial(var_type)			\

					; var = (var_type)__static_partial

#define INIT_STRUCT_assigned_static_all(var_type)			\

					; var = (var_type)__static_all

#define INIT_STRUCT_assigned_dynamic_partial(var_type)			\

					; var = (var_type)__dynamic_partial

#define INIT_STRUCT_assigned_dynamic_all(var_type)			\

					; var = (var_type)__dynamic_all



#define INIT_STRUCT_assigned_copy(var_type)				\

					; var = *(arg)



/*

 * @name: unique string name for the test

 * @var_type: type to be tested for zeroing initialization
@@ -167,7 +211,7 @@ static noinline __init int test_ ## name (void) \ 
	BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE);		\

								\

	/* Fill clone type with zero for per-field init. */	\

	memset(&zero, 0x00, sizeof(zero));			\

	ZERO_CLONE_ ## which(zero);				\

	/* Clear entire check buffer for 0xFF overlap test. */	\

	memset(check_buf, 0x00, sizeof(check_buf));		\

	/* Fill stack with 0xFF. */				\
@@ -210,7 +254,7 @@ static noinline __init int test_ ## name (void) \ 
		return (xfail) ? 0 : 1;				\

	}							\

}

#define DEFINE_TEST(name, var_type, which, init_level)		\

#define DEFINE_TEST(name, var_type, which, init_level, xfail)	\

/* no-op to force compiler into ignoring "uninitialized" vars */\

static noinline __init DO_NOTHING_TYPE_ ## which(var_type)	\

do_nothing_ ## name(var_type *ptr)				\
@@ -226,7 +270,8 @@ static noinline __init int leaf_ ## name(unsigned long sp, \ 
					 var_type *arg)		\

{								\

	char buf[VAR_BUFFER];					\

	var_type var INIT_ ## which ## _ ## init_level;		\

	var_type var						\

		INIT_ ## which ## _ ## init_level(var_type);	\

								\

	target_start = &var;					\

	target_size = sizeof(var);				\
@@ -252,7 +297,7 @@ static noinline __init int leaf_ ## name(unsigned long sp, \ 
								\

	return (int)buf[0] | (int)buf[sizeof(buf) - 1];		\

}								\

DEFINE_TEST_DRIVER(name, var_type, which, 0)

DEFINE_TEST_DRIVER(name, var_type, which, xfail)



/* Structure with no padding. */

struct test_packed {
@@ -296,42 +341,50 @@ struct test_user { 
	unsigned long four;

};



#define DEFINE_SCALAR_TEST(name, init)				\

		DEFINE_TEST(name ## _ ## init, name, SCALAR, init)

#define DEFINE_SCALAR_TEST(name, init, xfail)			\

		DEFINE_TEST(name ## _ ## init, name, SCALAR,	\

			    init, xfail)



#define DEFINE_SCALAR_TESTS(init)				\

		DEFINE_SCALAR_TEST(u8, init);			\

		DEFINE_SCALAR_TEST(u16, init);			\

		DEFINE_SCALAR_TEST(u32, init);			\

		DEFINE_SCALAR_TEST(u64, init);			\

		DEFINE_TEST(char_array_ ## init, unsigned char, STRING, init)

#define DEFINE_SCALAR_TESTS(init, xfail)			\

		DEFINE_SCALAR_TEST(u8, init, xfail);		\

		DEFINE_SCALAR_TEST(u16, init, xfail);		\

		DEFINE_SCALAR_TEST(u32, init, xfail);		\

		DEFINE_SCALAR_TEST(u64, init, xfail);		\

		DEFINE_TEST(char_array_ ## init, unsigned char,	\

			    STRING, init, xfail)



#define DEFINE_STRUCT_TEST(name, init)				\

#define DEFINE_STRUCT_TEST(name, init, xfail)			\

		DEFINE_TEST(name ## _ ## init,			\

			    struct test_ ## name, STRUCT, init)

			    struct test_ ## name, STRUCT, init, \

			    xfail)



#define DEFINE_STRUCT_TESTS(init, xfail)			\

		DEFINE_STRUCT_TEST(small_hole, init, xfail);	\

		DEFINE_STRUCT_TEST(big_hole, init, xfail);	\

		DEFINE_STRUCT_TEST(trailing_hole, init, xfail);	\

		DEFINE_STRUCT_TEST(packed, init, xfail)



#define DEFINE_STRUCT_TESTS(init)				\

		DEFINE_STRUCT_TEST(small_hole, init);		\

		DEFINE_STRUCT_TEST(big_hole, init);		\

		DEFINE_STRUCT_TEST(trailing_hole, init);	\

		DEFINE_STRUCT_TEST(packed, init)

#define DEFINE_STRUCT_INITIALIZER_TESTS(base)			\

		DEFINE_STRUCT_TESTS(base ## _ ## partial,	\

				    WANT_SUCCESS);		\

		DEFINE_STRUCT_TESTS(base ## _ ## all,		\

				    WANT_SUCCESS)



/* These should be fully initialized all the time! */

DEFINE_SCALAR_TESTS(zero);

DEFINE_STRUCT_TESTS(zero);

/* Static initialization: padding may be left uninitialized. */

DEFINE_STRUCT_TESTS(static_partial);

DEFINE_STRUCT_TESTS(static_all);

/* Dynamic initialization: padding may be left uninitialized. */

DEFINE_STRUCT_TESTS(dynamic_partial);

DEFINE_STRUCT_TESTS(dynamic_all);

/* Runtime initialization: padding may be left uninitialized. */

DEFINE_STRUCT_TESTS(runtime_partial);

DEFINE_STRUCT_TESTS(runtime_all);

DEFINE_SCALAR_TESTS(zero, WANT_SUCCESS);

DEFINE_STRUCT_TESTS(zero, WANT_SUCCESS);

/* Struct initializers: padding may be left uninitialized. */

DEFINE_STRUCT_INITIALIZER_TESTS(static);

DEFINE_STRUCT_INITIALIZER_TESTS(dynamic);

DEFINE_STRUCT_INITIALIZER_TESTS(runtime);

DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static);

DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic);

DEFINE_STRUCT_TESTS(assigned_copy, XFAIL);

/* No initialization without compiler instrumentation. */

DEFINE_SCALAR_TESTS(none);

DEFINE_STRUCT_TESTS(none);

DEFINE_TEST(user, struct test_user, STRUCT, none);

DEFINE_SCALAR_TESTS(none, WANT_SUCCESS);

DEFINE_STRUCT_TESTS(none, WANT_SUCCESS);

/* Initialization of members with __user attribute. */

DEFINE_TEST(user, struct test_user, STRUCT, none, WANT_SUCCESS);



/*

 * Check two uses through a variable declaration outside either path,
@@ -394,8 +447,8 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill, 
 * non-code areas (i.e. in a switch statement before the first "case").

 * https://bugs.llvm.org/show_bug.cgi?id=44916

 */

DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, 1);

DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, 1);

DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);

DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);



static int __init test_stackinit_init(void)

{
@@ -421,12 +474,18 @@ static int __init test_stackinit_init(void) 
	test_structs(zero);

	/* Padding here appears to be accidentally always initialized? */

	test_structs(dynamic_partial);

	test_structs(assigned_dynamic_partial);

	/* Padding initialization depends on compiler behaviors. */

	test_structs(static_partial);

	test_structs(static_all);

	test_structs(dynamic_all);

	test_structs(runtime_partial);

	test_structs(runtime_all);

	test_structs(assigned_static_partial);

	test_structs(assigned_static_all);

	test_structs(assigned_dynamic_all);

	/* Everything fails this since it effectively performs a memcpy(). */

	test_structs(assigned_copy);



	/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */

	test_scalars(none);