msan.cc revision c1a1ed62228288155459d39194995a36aca4a8a6
1//===-- msan.cc -----------------------------------------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file is a part of MemorySanitizer. 11// 12// MemorySanitizer runtime. 13//===----------------------------------------------------------------------===// 14 15#include "msan.h" 16#include "sanitizer_common/sanitizer_atomic.h" 17#include "sanitizer_common/sanitizer_common.h" 18#include "sanitizer_common/sanitizer_flags.h" 19#include "sanitizer_common/sanitizer_libc.h" 20#include "sanitizer_common/sanitizer_procmaps.h" 21#include "sanitizer_common/sanitizer_stacktrace.h" 22#include "sanitizer_common/sanitizer_symbolizer.h" 23 24#include "interception/interception.h" 25 26// ACHTUNG! No system header includes in this file. 27 28using namespace __sanitizer; 29 30// Globals. 31static THREADLOCAL int msan_expect_umr = 0; 32static THREADLOCAL int msan_expected_umr_found = 0; 33 34static int msan_running_under_dr = 0; 35 36SANITIZER_INTERFACE_ATTRIBUTE 37THREADLOCAL u64 __msan_param_tls[kMsanParamTlsSizeInWords]; 38 39SANITIZER_INTERFACE_ATTRIBUTE 40THREADLOCAL u32 __msan_param_origin_tls[kMsanParamTlsSizeInWords]; 41 42SANITIZER_INTERFACE_ATTRIBUTE 43THREADLOCAL u64 __msan_retval_tls[kMsanRetvalTlsSizeInWords]; 44 45SANITIZER_INTERFACE_ATTRIBUTE 46THREADLOCAL u32 __msan_retval_origin_tls; 47 48SANITIZER_INTERFACE_ATTRIBUTE 49THREADLOCAL u64 __msan_va_arg_tls[kMsanParamTlsSizeInWords]; 50 51SANITIZER_INTERFACE_ATTRIBUTE 52THREADLOCAL u64 __msan_va_arg_overflow_size_tls; 53 54SANITIZER_INTERFACE_ATTRIBUTE 55THREADLOCAL u32 __msan_origin_tls; 56 57static THREADLOCAL struct { 58 uptr stack_top, stack_bottom; 59} __msan_stack_bounds; 60 61static THREADLOCAL int is_in_symbolizer; 62static THREADLOCAL int is_in_loader; 63 64extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_track_origins; 65 66int __msan_get_track_origins() { 67 return &__msan_track_origins ? __msan_track_origins : 0; 68} 69 70extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_keep_going; 71 72namespace __msan { 73 74static bool IsRunningUnderDr() { 75 bool result = false; 76 MemoryMappingLayout proc_maps(/*cache_enabled*/true); 77 const sptr kBufSize = 4095; 78 char *filename = (char*)MmapOrDie(kBufSize, __FUNCTION__); 79 while (proc_maps.Next(/* start */0, /* end */0, /* file_offset */0, 80 filename, kBufSize, /* protection */0)) { 81 if (internal_strstr(filename, "libdynamorio") != 0) { 82 result = true; 83 break; 84 } 85 } 86 UnmapOrDie(filename, kBufSize); 87 return result; 88} 89 90void EnterSymbolizer() { ++is_in_symbolizer; } 91void ExitSymbolizer() { --is_in_symbolizer; } 92bool IsInSymbolizer() { return is_in_symbolizer; } 93 94void EnterLoader() { ++is_in_loader; } 95void ExitLoader() { --is_in_loader; } 96 97extern "C" { 98SANITIZER_INTERFACE_ATTRIBUTE 99bool __msan_is_in_loader() { return is_in_loader; } 100} 101 102static Flags msan_flags; 103 104Flags *flags() { 105 return &msan_flags; 106} 107 108int msan_inited = 0; 109bool msan_init_is_running; 110 111int msan_report_count = 0; 112 113// Array of stack origins. 114// FIXME: make it resizable. 115static const uptr kNumStackOriginDescrs = 1024 * 1024; 116static const char *StackOriginDescr[kNumStackOriginDescrs]; 117static uptr StackOriginPC[kNumStackOriginDescrs]; 118static atomic_uint32_t NumStackOriginDescrs; 119 120static void ParseFlagsFromString(Flags *f, const char *str) { 121 ParseCommonFlagsFromString(str); 122 ParseFlag(str, &f->poison_heap_with_zeroes, "poison_heap_with_zeroes"); 123 ParseFlag(str, &f->poison_stack_with_zeroes, "poison_stack_with_zeroes"); 124 ParseFlag(str, &f->poison_in_malloc, "poison_in_malloc"); 125 ParseFlag(str, &f->poison_in_malloc, "poison_in_free"); 126 ParseFlag(str, &f->exit_code, "exit_code"); 127 if (f->exit_code < 0 || f->exit_code > 127) { 128 Printf("Exit code not in [0, 128) range: %d\n", f->exit_code); 129 Die(); 130 } 131 ParseFlag(str, &f->report_umrs, "report_umrs"); 132 ParseFlag(str, &f->wrap_signals, "wrap_signals"); 133 134 // keep_going is an old name for halt_on_error, 135 // and it has inverse meaning. 136 f->halt_on_error = !f->halt_on_error; 137 ParseFlag(str, &f->halt_on_error, "keep_going"); 138 f->halt_on_error = !f->halt_on_error; 139 ParseFlag(str, &f->halt_on_error, "halt_on_error"); 140} 141 142static void InitializeFlags(Flags *f, const char *options) { 143 CommonFlags *cf = common_flags(); 144 cf->external_symbolizer_path = GetEnv("MSAN_SYMBOLIZER_PATH"); 145 cf->strip_path_prefix = ""; 146 cf->fast_unwind_on_fatal = false; 147 cf->fast_unwind_on_malloc = true; 148 cf->malloc_context_size = 20; 149 cf->handle_ioctl = true; 150 cf->log_path = 0; 151 152 internal_memset(f, 0, sizeof(*f)); 153 f->poison_heap_with_zeroes = false; 154 f->poison_stack_with_zeroes = false; 155 f->poison_in_malloc = true; 156 f->poison_in_free = true; 157 f->exit_code = 77; 158 f->report_umrs = true; 159 f->wrap_signals = true; 160 f->halt_on_error = !&__msan_keep_going; 161 162 // Override from user-specified string. 163 if (__msan_default_options) 164 ParseFlagsFromString(f, __msan_default_options()); 165 ParseFlagsFromString(f, options); 166} 167 168static void GetCurrentStackBounds(uptr *stack_top, uptr *stack_bottom) { 169 if (__msan_stack_bounds.stack_top == 0) { 170 // Break recursion (GetStackTrace -> GetThreadStackTopAndBottom -> 171 // realloc -> GetStackTrace). 172 __msan_stack_bounds.stack_top = __msan_stack_bounds.stack_bottom = 1; 173 GetThreadStackTopAndBottom(/* at_initialization */false, 174 &__msan_stack_bounds.stack_top, 175 &__msan_stack_bounds.stack_bottom); 176 } 177 *stack_top = __msan_stack_bounds.stack_top; 178 *stack_bottom = __msan_stack_bounds.stack_bottom; 179} 180 181void GetStackTrace(StackTrace *stack, uptr max_s, uptr pc, uptr bp, 182 bool fast) { 183 if (!fast) { 184 // Block reports from our interceptors during _Unwind_Backtrace. 185 SymbolizerScope sym_scope; 186 return stack->SlowUnwindStack(pc, max_s); 187 } 188 189 uptr stack_top, stack_bottom; 190 GetCurrentStackBounds(&stack_top, &stack_bottom); 191 stack->FastUnwindStack(pc, bp, stack_top, stack_bottom, max_s); 192} 193 194void PrintWarning(uptr pc, uptr bp) { 195 PrintWarningWithOrigin(pc, bp, __msan_origin_tls); 196} 197 198bool OriginIsValid(u32 origin) { 199 return origin != 0 && origin != (u32)-1; 200} 201 202void PrintWarningWithOrigin(uptr pc, uptr bp, u32 origin) { 203 if (msan_expect_umr) { 204 // Printf("Expected UMR\n"); 205 __msan_origin_tls = origin; 206 msan_expected_umr_found = 1; 207 return; 208 } 209 210 ++msan_report_count; 211 212 StackTrace stack; 213 GetStackTrace(&stack, kStackTraceMax, pc, bp, 214 common_flags()->fast_unwind_on_fatal); 215 216 u32 report_origin = 217 (__msan_get_track_origins() && OriginIsValid(origin)) ? origin : 0; 218 ReportUMR(&stack, report_origin); 219 220 if (__msan_get_track_origins() && !OriginIsValid(origin)) { 221 Printf( 222 " ORIGIN: invalid (%x). Might be a bug in MemorySanitizer origin " 223 "tracking.\n This could still be a bug in your code, too!\n", 224 origin); 225 } 226} 227 228void UnpoisonParam(uptr n) { 229 internal_memset(__msan_param_tls, 0, n * sizeof(*__msan_param_tls)); 230} 231 232// Backup MSan runtime TLS state. 233// Implementation must be async-signal-safe. 234// Instances of this class may live on the signal handler stack, and data size 235// may be an issue. 236void ScopedThreadLocalStateBackup::Backup() { 237 va_arg_overflow_size_tls = __msan_va_arg_overflow_size_tls; 238} 239 240void ScopedThreadLocalStateBackup::Restore() { 241 // A lame implementation that only keeps essential state and resets the rest. 242 __msan_va_arg_overflow_size_tls = va_arg_overflow_size_tls; 243 244 internal_memset(__msan_param_tls, 0, sizeof(__msan_param_tls)); 245 internal_memset(__msan_retval_tls, 0, sizeof(__msan_retval_tls)); 246 internal_memset(__msan_va_arg_tls, 0, sizeof(__msan_va_arg_tls)); 247 248 if (__msan_get_track_origins()) { 249 internal_memset(&__msan_retval_origin_tls, 0, sizeof(__msan_retval_tls)); 250 internal_memset(__msan_param_origin_tls, 0, 251 sizeof(__msan_param_origin_tls)); 252 } 253} 254 255void UnpoisonThreadLocalState() { 256} 257 258const char *GetOriginDescrIfStack(u32 id, uptr *pc) { 259 if ((id >> 31) == 0) return 0; 260 id &= (1U << 31) - 1; 261 CHECK_LT(id, kNumStackOriginDescrs); 262 if (pc) *pc = StackOriginPC[id]; 263 return StackOriginDescr[id]; 264} 265 266} // namespace __msan 267 268// Interface. 269 270using namespace __msan; 271 272void __msan_warning() { 273 GET_CALLER_PC_BP_SP; 274 (void)sp; 275 PrintWarning(pc, bp); 276 if (__msan::flags()->halt_on_error) { 277 Printf("Exiting\n"); 278 Die(); 279 } 280} 281 282void __msan_warning_noreturn() { 283 GET_CALLER_PC_BP_SP; 284 (void)sp; 285 PrintWarning(pc, bp); 286 Printf("Exiting\n"); 287 Die(); 288} 289 290void __msan_init() { 291 if (msan_inited) return; 292 msan_init_is_running = 1; 293 SanitizerToolName = "MemorySanitizer"; 294 295 SetDieCallback(MsanDie); 296 InitTlsSize(); 297 InitializeInterceptors(); 298 InstallAtExitHandler(); // Needs __cxa_atexit interceptor. 299 300 if (MSAN_REPLACE_OPERATORS_NEW_AND_DELETE) 301 ReplaceOperatorsNewAndDelete(); 302 const char *msan_options = GetEnv("MSAN_OPTIONS"); 303 InitializeFlags(&msan_flags, msan_options); 304 __sanitizer_set_report_path(common_flags()->log_path); 305 if (StackSizeIsUnlimited()) { 306 if (common_flags()->verbosity) 307 Printf("Unlimited stack, doing reexec\n"); 308 // A reasonably large stack size. It is bigger than the usual 8Mb, because, 309 // well, the program could have been run with unlimited stack for a reason. 310 SetStackSizeLimitInBytes(32 * 1024 * 1024); 311 ReExec(); 312 } 313 314 if (common_flags()->verbosity) 315 Printf("MSAN_OPTIONS: %s\n", msan_options ? msan_options : "<empty>"); 316 317 msan_running_under_dr = IsRunningUnderDr(); 318 __msan_clear_on_return(); 319 if (__msan_get_track_origins() && common_flags()->verbosity > 0) 320 Printf("msan_track_origins\n"); 321 if (!InitShadow(/* prot1 */ false, /* prot2 */ true, /* map_shadow */ true, 322 __msan_get_track_origins())) { 323 // FIXME: prot1 = false is only required when running under DR. 324 Printf("FATAL: MemorySanitizer can not mmap the shadow memory.\n"); 325 Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n"); 326 Printf("FATAL: Disabling ASLR is known to cause this error.\n"); 327 Printf("FATAL: If running under GDB, try " 328 "'set disable-randomization off'.\n"); 329 DumpProcessMap(); 330 Die(); 331 } 332 333 const char *external_symbolizer = common_flags()->external_symbolizer_path; 334 bool external_symbolizer_started = 335 Symbolizer::Init(external_symbolizer)->IsExternalAvailable(); 336 if (external_symbolizer && external_symbolizer[0]) { 337 CHECK(external_symbolizer_started); 338 } 339 340 GetThreadStackTopAndBottom(/* at_initialization */true, 341 &__msan_stack_bounds.stack_top, 342 &__msan_stack_bounds.stack_bottom); 343 if (common_flags()->verbosity) 344 Printf("MemorySanitizer init done\n"); 345 msan_init_is_running = 0; 346 msan_inited = 1; 347} 348 349void __msan_set_exit_code(int exit_code) { 350 flags()->exit_code = exit_code; 351} 352 353void __msan_set_keep_going(int keep_going) { 354 flags()->halt_on_error = !keep_going; 355} 356 357void __msan_set_expect_umr(int expect_umr) { 358 if (expect_umr) { 359 msan_expected_umr_found = 0; 360 } else if (!msan_expected_umr_found) { 361 GET_CALLER_PC_BP_SP; 362 (void)sp; 363 StackTrace stack; 364 GetStackTrace(&stack, kStackTraceMax, pc, bp, 365 common_flags()->fast_unwind_on_fatal); 366 ReportExpectedUMRNotFound(&stack); 367 Die(); 368 } 369 msan_expect_umr = expect_umr; 370} 371 372void __msan_print_shadow(const void *x, uptr size) { 373 unsigned char *s = (unsigned char*)MEM_TO_SHADOW(x); 374 u32 *o = (u32*)MEM_TO_ORIGIN(x); 375 for (uptr i = 0; i < size; i++) { 376 Printf("%x%x ", s[i] >> 4, s[i] & 0xf); 377 } 378 Printf("\n"); 379 if (__msan_get_track_origins()) { 380 for (uptr i = 0; i < size / 4; i++) { 381 Printf(" o: %x ", o[i]); 382 } 383 Printf("\n"); 384 } 385} 386 387void __msan_print_param_shadow() { 388 for (int i = 0; i < 16; i++) { 389 Printf("#%d:%zx ", i, __msan_param_tls[i]); 390 } 391 Printf("\n"); 392} 393 394sptr __msan_test_shadow(const void *x, uptr size) { 395 unsigned char *s = (unsigned char*)MEM_TO_SHADOW((uptr)x); 396 for (uptr i = 0; i < size; ++i) 397 if (s[i]) 398 return i; 399 return -1; 400} 401 402int __msan_set_poison_in_malloc(int do_poison) { 403 int old = flags()->poison_in_malloc; 404 flags()->poison_in_malloc = do_poison; 405 return old; 406} 407 408int __msan_has_dynamic_component() { 409 return msan_running_under_dr; 410} 411 412NOINLINE 413void __msan_clear_on_return() { 414 __msan_param_tls[0] = 0; 415} 416 417static void* get_tls_base() { 418 u64 p; 419 asm("mov %%fs:0, %0" 420 : "=r"(p) ::); 421 return (void*)p; 422} 423 424int __msan_get_retval_tls_offset() { 425 // volatile here is needed to avoid UB, because the compiler thinks that we 426 // are doing address arithmetics on unrelated pointers, and takes some 427 // shortcuts 428 volatile sptr retval_tls_p = (sptr)&__msan_retval_tls; 429 volatile sptr tls_base_p = (sptr)get_tls_base(); 430 return retval_tls_p - tls_base_p; 431} 432 433int __msan_get_param_tls_offset() { 434 // volatile here is needed to avoid UB, because the compiler thinks that we 435 // are doing address arithmetics on unrelated pointers, and takes some 436 // shortcuts 437 volatile sptr param_tls_p = (sptr)&__msan_param_tls; 438 volatile sptr tls_base_p = (sptr)get_tls_base(); 439 return param_tls_p - tls_base_p; 440} 441 442void __msan_partial_poison(const void* data, void* shadow, uptr size) { 443 internal_memcpy((void*)MEM_TO_SHADOW((uptr)data), shadow, size); 444} 445 446void __msan_load_unpoisoned(void *src, uptr size, void *dst) { 447 internal_memcpy(dst, src, size); 448 __msan_unpoison(dst, size); 449} 450 451void __msan_set_origin(const void *a, uptr size, u32 origin) { 452 // Origin mapping is 4 bytes per 4 bytes of application memory. 453 // Here we extend the range such that its left and right bounds are both 454 // 4 byte aligned. 455 if (!__msan_get_track_origins()) return; 456 uptr x = MEM_TO_ORIGIN((uptr)a); 457 uptr beg = x & ~3UL; // align down. 458 uptr end = (x + size + 3) & ~3UL; // align up. 459 u64 origin64 = ((u64)origin << 32) | origin; 460 // This is like memset, but the value is 32-bit. We unroll by 2 two write 461 // 64-bits at once. May want to unroll further to get 128-bit stores. 462 if (beg & 7ULL) { 463 *(u32*)beg = origin; 464 beg += 4; 465 } 466 for (uptr addr = beg; addr < (end & ~7UL); addr += 8) 467 *(u64*)addr = origin64; 468 if (end & 7ULL) 469 *(u32*)(end - 4) = origin; 470} 471 472// 'descr' is created at compile time and contains '----' in the beginning. 473// When we see descr for the first time we replace '----' with a uniq id 474// and set the origin to (id | (31-th bit)). 475void __msan_set_alloca_origin(void *a, uptr size, const char *descr) { 476 __msan_set_alloca_origin4(a, size, descr, 0); 477} 478 479void __msan_set_alloca_origin4(void *a, uptr size, const char *descr, uptr pc) { 480 static const u32 dash = '-'; 481 static const u32 first_timer = 482 dash + (dash << 8) + (dash << 16) + (dash << 24); 483 u32 *id_ptr = (u32*)descr; 484 bool print = false; // internal_strstr(descr + 4, "AllocaTOTest") != 0; 485 u32 id = *id_ptr; 486 if (id == first_timer) { 487 id = atomic_fetch_add(&NumStackOriginDescrs, 488 1, memory_order_relaxed); 489 *id_ptr = id; 490 CHECK_LT(id, kNumStackOriginDescrs); 491 StackOriginDescr[id] = descr + 4; 492 StackOriginPC[id] = pc; 493 if (print) 494 Printf("First time: id=%d %s %p \n", id, descr + 4, pc); 495 } 496 id |= 1U << 31; 497 if (print) 498 Printf("__msan_set_alloca_origin: descr=%s id=%x\n", descr + 4, id); 499 __msan_set_origin(a, size, id); 500} 501 502const char *__msan_get_origin_descr_if_stack(u32 id) { 503 return GetOriginDescrIfStack(id, 0); 504} 505 506u32 __msan_get_origin(const void *a) { 507 if (!__msan_get_track_origins()) return 0; 508 uptr x = (uptr)a; 509 uptr aligned = x & ~3ULL; 510 uptr origin_ptr = MEM_TO_ORIGIN(aligned); 511 return *(u32*)origin_ptr; 512} 513 514u32 __msan_get_umr_origin() { 515 return __msan_origin_tls; 516} 517 518u16 __sanitizer_unaligned_load16(const uu16 *p) { 519 __msan_retval_tls[0] = *(uu16 *)MEM_TO_SHADOW((uptr)p); 520 if (__msan_get_track_origins()) 521 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 522 return *p; 523} 524u32 __sanitizer_unaligned_load32(const uu32 *p) { 525 __msan_retval_tls[0] = *(uu32 *)MEM_TO_SHADOW((uptr)p); 526 if (__msan_get_track_origins()) 527 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 528 return *p; 529} 530u64 __sanitizer_unaligned_load64(const uu64 *p) { 531 __msan_retval_tls[0] = *(uu64 *)MEM_TO_SHADOW((uptr)p); 532 if (__msan_get_track_origins()) 533 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 534 return *p; 535} 536void __sanitizer_unaligned_store16(uu16 *p, u16 x) { 537 *(uu16 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 538 if (__msan_get_track_origins()) 539 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 540 *p = x; 541} 542void __sanitizer_unaligned_store32(uu32 *p, u32 x) { 543 *(uu32 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 544 if (__msan_get_track_origins()) 545 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 546 *p = x; 547} 548void __sanitizer_unaligned_store64(uu64 *p, u64 x) { 549 *(uu64 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 550 if (__msan_get_track_origins()) 551 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 552 *p = x; 553} 554 555#if !SANITIZER_SUPPORTS_WEAK_HOOKS 556extern "C" { 557SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE 558const char* __msan_default_options() { return ""; } 559} // extern "C" 560#endif 561 562