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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Test cases for compiler-based stack variable zeroing via
4 * -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
5 * For example, see:
6 * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst
7 * ./tools/testing/kunit/kunit.py run stackinit [--raw_output] \
8 * --make_option LLVM=1 \
9 * --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
10 *
11 */
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <kunit/test.h>
15#include <linux/init.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/string.h>
19
20/* Exfiltration buffer. */
21#define MAX_VAR_SIZE 128
22static u8 check_buf[MAX_VAR_SIZE];
23
24/* Character array to trigger stack protector in all functions. */
25#define VAR_BUFFER 32
26
27/* Volatile mask to convince compiler to copy memory with 0xff. */
28static volatile u8 forced_mask = 0xff;
29
30/* Location and size tracking to validate fill and test are colocated. */
31static void *fill_start, *target_start;
32static size_t fill_size, target_size;
33
34static bool range_contains(char *haystack_start, size_t haystack_size,
35 char *needle_start, size_t needle_size)
36{
37 if (needle_start >= haystack_start &&
38 needle_start + needle_size <= haystack_start + haystack_size)
39 return true;
40 return false;
41}
42
43/* Whether the test is expected to fail. */
44#define WANT_SUCCESS 0
45#define XFAIL 1
46
47#define DO_NOTHING_TYPE_SCALAR(var_type) var_type
48#define DO_NOTHING_TYPE_STRING(var_type) void
49#define DO_NOTHING_TYPE_STRUCT(var_type) void
50
51#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)
52#define DO_NOTHING_RETURN_STRING(ptr) /**/
53#define DO_NOTHING_RETURN_STRUCT(ptr) /**/
54
55#define DO_NOTHING_CALL_SCALAR(var, name) \
56 (var) = do_nothing_ ## name(&(var))
57#define DO_NOTHING_CALL_STRING(var, name) \
58 do_nothing_ ## name(var)
59#define DO_NOTHING_CALL_STRUCT(var, name) \
60 do_nothing_ ## name(&(var))
61
62#define FETCH_ARG_SCALAR(var) &var
63#define FETCH_ARG_STRING(var) var
64#define FETCH_ARG_STRUCT(var) &var
65
66#define FILL_SIZE_STRING 16
67
68#define INIT_CLONE_SCALAR /**/
69#define INIT_CLONE_STRING [FILL_SIZE_STRING]
70#define INIT_CLONE_STRUCT /**/
71
72#define ZERO_CLONE_SCALAR(zero) memset(&(zero), 0x00, sizeof(zero))
73#define ZERO_CLONE_STRING(zero) memset(&(zero), 0x00, sizeof(zero))
74/*
75 * For the struct, intentionally poison padding to see if it gets
76 * copied out in direct assignments.
77 * */
78#define ZERO_CLONE_STRUCT(zero) \
79 do { \
80 memset(&(zero), 0xFF, sizeof(zero)); \
81 zero.one = 0; \
82 zero.two = 0; \
83 zero.three = 0; \
84 zero.four = 0; \
85 } while (0)
86
87#define INIT_SCALAR_none(var_type) /**/
88#define INIT_SCALAR_zero(var_type) = 0
89
90#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/
91#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { }
92
93#define INIT_STRUCT_none(var_type) /**/
94#define INIT_STRUCT_zero(var_type) = { }
95
96
97#define __static_partial { .two = 0, }
98#define __static_all { .one = 0, \
99 .two = 0, \
100 .three = 0, \
101 .four = 0, \
102 }
103#define __dynamic_partial { .two = arg->two, }
104#define __dynamic_all { .one = arg->one, \
105 .two = arg->two, \
106 .three = arg->three, \
107 .four = arg->four, \
108 }
109#define __runtime_partial var.two = 0
110#define __runtime_all var.one = 0; \
111 var.two = 0; \
112 var.three = 0; \
113 var.four = 0
114
115#define INIT_STRUCT_static_partial(var_type) \
116 = __static_partial
117#define INIT_STRUCT_static_all(var_type) \
118 = __static_all
119#define INIT_STRUCT_dynamic_partial(var_type) \
120 = __dynamic_partial
121#define INIT_STRUCT_dynamic_all(var_type) \
122 = __dynamic_all
123#define INIT_STRUCT_runtime_partial(var_type) \
124 ; __runtime_partial
125#define INIT_STRUCT_runtime_all(var_type) \
126 ; __runtime_all
127
128#define INIT_STRUCT_assigned_static_partial(var_type) \
129 ; var = (var_type)__static_partial
130#define INIT_STRUCT_assigned_static_all(var_type) \
131 ; var = (var_type)__static_all
132#define INIT_STRUCT_assigned_dynamic_partial(var_type) \
133 ; var = (var_type)__dynamic_partial
134#define INIT_STRUCT_assigned_dynamic_all(var_type) \
135 ; var = (var_type)__dynamic_all
136
137#define INIT_STRUCT_assigned_copy(var_type) \
138 ; var = *(arg)
139
140/*
141 * @name: unique string name for the test
142 * @var_type: type to be tested for zeroing initialization
143 * @which: is this a SCALAR, STRING, or STRUCT type?
144 * @init_level: what kind of initialization is performed
145 * @xfail: is this test expected to fail?
146 */
147#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \
148/* Returns 0 on success, 1 on failure. */ \
149static noinline void test_ ## name (struct kunit *test) \
150{ \
151 var_type zero INIT_CLONE_ ## which; \
152 int ignored; \
153 u8 sum = 0, i; \
154 \
155 /* Notice when a new test is larger than expected. */ \
156 BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \
157 \
158 /* Fill clone type with zero for per-field init. */ \
159 ZERO_CLONE_ ## which(zero); \
160 /* Clear entire check buffer for 0xFF overlap test. */ \
161 memset(check_buf, 0x00, sizeof(check_buf)); \
162 /* Fill stack with 0xFF. */ \
163 ignored = leaf_ ##name((unsigned long)&ignored, 1, \
164 FETCH_ARG_ ## which(zero)); \
165 /* Verify all bytes overwritten with 0xFF. */ \
166 for (sum = 0, i = 0; i < target_size; i++) \
167 sum += (check_buf[i] != 0xFF); \
168 KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
169 "leaf fill was not 0xFF!?\n"); \
170 /* Clear entire check buffer for later bit tests. */ \
171 memset(check_buf, 0x00, sizeof(check_buf)); \
172 /* Extract stack-defined variable contents. */ \
173 ignored = leaf_ ##name((unsigned long)&ignored, 0, \
174 FETCH_ARG_ ## which(zero)); \
175 \
176 /* Validate that compiler lined up fill and target. */ \
177 KUNIT_ASSERT_TRUE_MSG(test, \
178 range_contains(fill_start, fill_size, \
179 target_start, target_size), \
180 "stack fill missed target!? " \
181 "(fill %zu wide, target offset by %d)\n", \
182 fill_size, \
183 (int)((ssize_t)(uintptr_t)fill_start - \
184 (ssize_t)(uintptr_t)target_start)); \
185 \
186 /* Look for any bytes still 0xFF in check region. */ \
187 for (sum = 0, i = 0; i < target_size; i++) \
188 sum += (check_buf[i] == 0xFF); \
189 \
190 if (sum != 0 && xfail) \
191 kunit_skip(test, \
192 "XFAIL uninit bytes: %d\n", \
193 sum); \
194 KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
195 "uninit bytes: %d\n", sum); \
196}
197#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
198/* no-op to force compiler into ignoring "uninitialized" vars */\
199static noinline DO_NOTHING_TYPE_ ## which(var_type) \
200do_nothing_ ## name(var_type *ptr) \
201{ \
202 /* Will always be true, but compiler doesn't know. */ \
203 if ((unsigned long)ptr > 0x2) \
204 return DO_NOTHING_RETURN_ ## which(ptr); \
205 else \
206 return DO_NOTHING_RETURN_ ## which(ptr + 1); \
207} \
208static noinline int leaf_ ## name(unsigned long sp, bool fill, \
209 var_type *arg) \
210{ \
211 char buf[VAR_BUFFER]; \
212 var_type var \
213 INIT_ ## which ## _ ## init_level(var_type); \
214 \
215 target_start = &var; \
216 target_size = sizeof(var); \
217 /* \
218 * Keep this buffer around to make sure we've got a \
219 * stack frame of SOME kind... \
220 */ \
221 memset(buf, (char)(sp & 0xff), sizeof(buf)); \
222 /* Fill variable with 0xFF. */ \
223 if (fill) { \
224 fill_start = &var; \
225 fill_size = sizeof(var); \
226 memset(fill_start, \
227 (char)((sp & 0xff) | forced_mask), \
228 fill_size); \
229 } \
230 \
231 /* Silence "never initialized" warnings. */ \
232 DO_NOTHING_CALL_ ## which(var, name); \
233 \
234 /* Exfiltrate "var". */ \
235 memcpy(check_buf, target_start, target_size); \
236 \
237 return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \
238} \
239DEFINE_TEST_DRIVER(name, var_type, which, xfail)
240
241/* Structure with no padding. */
242struct test_packed {
243 unsigned long one;
244 unsigned long two;
245 unsigned long three;
246 unsigned long four;
247};
248
249/* Simple structure with padding likely to be covered by compiler. */
250struct test_small_hole {
251 size_t one;
252 char two;
253 /* 3 byte padding hole here. */
254 int three;
255 unsigned long four;
256};
257
258/* Trigger unhandled padding in a structure. */
259struct test_big_hole {
260 u8 one;
261 u8 two;
262 u8 three;
263 /* 61 byte padding hole here. */
264 u8 four __aligned(64);
265} __aligned(64);
266
267struct test_trailing_hole {
268 char *one;
269 char *two;
270 char *three;
271 char four;
272 /* "sizeof(unsigned long) - 1" byte padding hole here. */
273};
274
275/* Test if STRUCTLEAK is clearing structs with __user fields. */
276struct test_user {
277 u8 one;
278 unsigned long two;
279 char __user *three;
280 unsigned long four;
281};
282
283#define ALWAYS_PASS WANT_SUCCESS
284#define ALWAYS_FAIL XFAIL
285
286#ifdef CONFIG_INIT_STACK_NONE
287# define USER_PASS XFAIL
288# define BYREF_PASS XFAIL
289# define STRONG_PASS XFAIL
290#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER)
291# define USER_PASS WANT_SUCCESS
292# define BYREF_PASS XFAIL
293# define STRONG_PASS XFAIL
294#elif defined(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF)
295# define USER_PASS WANT_SUCCESS
296# define BYREF_PASS WANT_SUCCESS
297# define STRONG_PASS XFAIL
298#else
299# define USER_PASS WANT_SUCCESS
300# define BYREF_PASS WANT_SUCCESS
301# define STRONG_PASS WANT_SUCCESS
302#endif
303
304#define DEFINE_SCALAR_TEST(name, init, xfail) \
305 DEFINE_TEST(name ## _ ## init, name, SCALAR, \
306 init, xfail)
307
308#define DEFINE_SCALAR_TESTS(init, xfail) \
309 DEFINE_SCALAR_TEST(u8, init, xfail); \
310 DEFINE_SCALAR_TEST(u16, init, xfail); \
311 DEFINE_SCALAR_TEST(u32, init, xfail); \
312 DEFINE_SCALAR_TEST(u64, init, xfail); \
313 DEFINE_TEST(char_array_ ## init, unsigned char, \
314 STRING, init, xfail)
315
316#define DEFINE_STRUCT_TEST(name, init, xfail) \
317 DEFINE_TEST(name ## _ ## init, \
318 struct test_ ## name, STRUCT, init, \
319 xfail)
320
321#define DEFINE_STRUCT_TESTS(init, xfail) \
322 DEFINE_STRUCT_TEST(small_hole, init, xfail); \
323 DEFINE_STRUCT_TEST(big_hole, init, xfail); \
324 DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
325 DEFINE_STRUCT_TEST(packed, init, xfail)
326
327#define DEFINE_STRUCT_INITIALIZER_TESTS(base, xfail) \
328 DEFINE_STRUCT_TESTS(base ## _ ## partial, \
329 xfail); \
330 DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)
331
332/* These should be fully initialized all the time! */
333DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);
334DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);
335/* Struct initializers: padding may be left uninitialized. */
336DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);
337DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);
338DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);
339DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);
340DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);
341DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);
342/* No initialization without compiler instrumentation. */
343DEFINE_SCALAR_TESTS(none, STRONG_PASS);
344DEFINE_STRUCT_TESTS(none, BYREF_PASS);
345/* Initialization of members with __user attribute. */
346DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);
347
348/*
349 * Check two uses through a variable declaration outside either path,
350 * which was noticed as a special case in porting earlier stack init
351 * compiler logic.
352 */
353static int noinline __leaf_switch_none(int path, bool fill)
354{
355 switch (path) {
356 /*
357 * This is intentionally unreachable. To silence the
358 * warning, build with -Wno-switch-unreachable
359 */
360 uint64_t var[10];
361
362 case 1:
363 target_start = &var;
364 target_size = sizeof(var);
365 if (fill) {
366 fill_start = &var;
367 fill_size = sizeof(var);
368
369 memset(fill_start, forced_mask | 0x55, fill_size);
370 }
371 memcpy(check_buf, target_start, target_size);
372 break;
373 case 2:
374 target_start = &var;
375 target_size = sizeof(var);
376 if (fill) {
377 fill_start = &var;
378 fill_size = sizeof(var);
379
380 memset(fill_start, forced_mask | 0xaa, fill_size);
381 }
382 memcpy(check_buf, target_start, target_size);
383 break;
384 default:
385 var[1] = 5;
386 return var[1] & forced_mask;
387 }
388 return 0;
389}
390
391static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
392 uint64_t *arg)
393{
394 return __leaf_switch_none(1, fill);
395}
396
397static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
398 uint64_t *arg)
399{
400 return __leaf_switch_none(2, fill);
401}
402
403/*
404 * These are expected to fail for most configurations because neither
405 * GCC nor Clang have a way to perform initialization of variables in
406 * non-code areas (i.e. in a switch statement before the first "case").
407 * https://bugs.llvm.org/show_bug.cgi?id=44916
408 */
409DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);
410DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
411
412#define KUNIT_test_scalars(init) \
413 KUNIT_CASE(test_u8_ ## init), \
414 KUNIT_CASE(test_u16_ ## init), \
415 KUNIT_CASE(test_u32_ ## init), \
416 KUNIT_CASE(test_u64_ ## init), \
417 KUNIT_CASE(test_char_array_ ## init)
418
419#define KUNIT_test_structs(init) \
420 KUNIT_CASE(test_small_hole_ ## init), \
421 KUNIT_CASE(test_big_hole_ ## init), \
422 KUNIT_CASE(test_trailing_hole_ ## init),\
423 KUNIT_CASE(test_packed_ ## init) \
424
425static struct kunit_case stackinit_test_cases[] = {
426 /* These are explicitly initialized and should always pass. */
427 KUNIT_test_scalars(zero),
428 KUNIT_test_structs(zero),
429 /* Padding here appears to be accidentally always initialized? */
430 KUNIT_test_structs(dynamic_partial),
431 KUNIT_test_structs(assigned_dynamic_partial),
432 /* Padding initialization depends on compiler behaviors. */
433 KUNIT_test_structs(static_partial),
434 KUNIT_test_structs(static_all),
435 KUNIT_test_structs(dynamic_all),
436 KUNIT_test_structs(runtime_partial),
437 KUNIT_test_structs(runtime_all),
438 KUNIT_test_structs(assigned_static_partial),
439 KUNIT_test_structs(assigned_static_all),
440 KUNIT_test_structs(assigned_dynamic_all),
441 /* Everything fails this since it effectively performs a memcpy(). */
442 KUNIT_test_structs(assigned_copy),
443 /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
444 KUNIT_test_scalars(none),
445 KUNIT_CASE(test_switch_1_none),
446 KUNIT_CASE(test_switch_2_none),
447 /* STRUCTLEAK_BYREF should cover from here down. */
448 KUNIT_test_structs(none),
449 /* STRUCTLEAK will only cover this. */
450 KUNIT_CASE(test_user),
451 {}
452};
453
454static struct kunit_suite stackinit_test_suite = {
455 .name = "stackinit",
456 .test_cases = stackinit_test_cases,
457};
458
459kunit_test_suites(&stackinit_test_suite);
460
461MODULE_LICENSE("GPL");