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lib/test_stackinit: Add assigned initializers
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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: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/CAK8P3a20SEoYCrp3jOK32oZc9OkiPv+1KTjNZ2GxLbHpY4WexQ@mail.gmail.com
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210723221933.3431999-4-keescook@chromium.org
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Kees Cook committed Aug 22, 2021
1 parent 1e2cd30 commit a8fc576
Showing 1 changed file with 114 additions and 55 deletions.
169 changes: 114 additions & 55 deletions lib/test_stackinit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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, \
.two = 0, \
.three = 0, \
.four = 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, \
.two = arg->two, \
.three = arg->three, \
.four = arg->four, \
#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
Expand All @@ -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. */ \
Expand Down Expand Up @@ -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) \
Expand All @@ -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); \
Expand All @@ -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 {
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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)
{
Expand All @@ -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);
Expand Down

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