| 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 |
| 22 | static 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. */ |
| 28 | static volatile u8 forced_mask = 0xff; |
| 29 | |
| 30 | /* Location and size tracking to validate fill and test are colocated. */ |
| 31 | static void *fill_start, *target_start; |
| 32 | static size_t fill_size, target_size; |
| 33 | |
| 34 | static bool stackinit_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. */ \ |
| 149 | static 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 | stackinit_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 */\ |
| 199 | static noinline DO_NOTHING_TYPE_ ## which(var_type) \ |
| 200 | do_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 | } \ |
| 208 | static 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 | } \ |
| 239 | DEFINE_TEST_DRIVER(name, var_type, which, xfail) |
| 240 | |
| 241 | /* Structure with no padding. */ |
| 242 | struct 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. */ |
| 250 | struct 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. */ |
| 259 | struct 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 | |
| 267 | struct 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. */ |
| 276 | struct 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! */ |
| 333 | DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS); |
| 334 | DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS); |
| 335 | /* Struct initializers: padding may be left uninitialized. */ |
| 336 | DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS); |
| 337 | DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS); |
| 338 | DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS); |
| 339 | DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS); |
| 340 | DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS); |
| 341 | DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL); |
| 342 | /* No initialization without compiler instrumentation. */ |
| 343 | DEFINE_SCALAR_TESTS(none, STRONG_PASS); |
| 344 | DEFINE_STRUCT_TESTS(none, BYREF_PASS); |
| 345 | /* Initialization of members with __user attribute. */ |
| 346 | DEFINE_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 | */ |
| 353 | static 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 | |
| 391 | static 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 | |
| 397 | static 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 | */ |
| 409 | DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL); |
| 410 | DEFINE_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 | |
| 425 | static 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 | |
| 454 | static struct kunit_suite stackinit_test_suite = { |
| 455 | .name = "stackinit", |
| 456 | .test_cases = stackinit_test_cases, |
| 457 | }; |
| 458 | |
| 459 | kunit_test_suites(&stackinit_test_suite); |
| 460 | |
| 461 | MODULE_LICENSE("GPL"); |