msan.cc revision 66d91e3356a0c4d7aff3beaaaff3e87bbaec805c
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_free, "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->symbolize = true; 146 cf->strip_path_prefix = ""; 147 cf->fast_unwind_on_fatal = false; 148 cf->fast_unwind_on_malloc = true; 149 cf->malloc_context_size = 20; 150 cf->handle_ioctl = true; 151 cf->log_path = 0; 152 153 internal_memset(f, 0, sizeof(*f)); 154 f->poison_heap_with_zeroes = false; 155 f->poison_stack_with_zeroes = false; 156 f->poison_in_malloc = true; 157 f->poison_in_free = true; 158 f->exit_code = 77; 159 f->report_umrs = true; 160 f->wrap_signals = true; 161 f->halt_on_error = !&__msan_keep_going; 162 163 // Override from user-specified string. 164 if (__msan_default_options) 165 ParseFlagsFromString(f, __msan_default_options()); 166 ParseFlagsFromString(f, options); 167} 168 169static void GetCurrentStackBounds(uptr *stack_top, uptr *stack_bottom) { 170 if (__msan_stack_bounds.stack_top == 0) { 171 // Break recursion (GetStackTrace -> GetThreadStackTopAndBottom -> 172 // realloc -> GetStackTrace). 173 __msan_stack_bounds.stack_top = __msan_stack_bounds.stack_bottom = 1; 174 GetThreadStackTopAndBottom(/* at_initialization */false, 175 &__msan_stack_bounds.stack_top, 176 &__msan_stack_bounds.stack_bottom); 177 } 178 *stack_top = __msan_stack_bounds.stack_top; 179 *stack_bottom = __msan_stack_bounds.stack_bottom; 180} 181 182void GetStackTrace(StackTrace *stack, uptr max_s, uptr pc, uptr bp, 183 bool fast) { 184 if (!fast) { 185 // Block reports from our interceptors during _Unwind_Backtrace. 186 SymbolizerScope sym_scope; 187 return stack->SlowUnwindStack(pc, max_s); 188 } 189 190 uptr stack_top, stack_bottom; 191 GetCurrentStackBounds(&stack_top, &stack_bottom); 192 stack->FastUnwindStack(pc, bp, stack_top, stack_bottom, max_s); 193} 194 195void PrintWarning(uptr pc, uptr bp) { 196 PrintWarningWithOrigin(pc, bp, __msan_origin_tls); 197} 198 199bool OriginIsValid(u32 origin) { 200 return origin != 0 && origin != (u32)-1; 201} 202 203void PrintWarningWithOrigin(uptr pc, uptr bp, u32 origin) { 204 if (msan_expect_umr) { 205 // Printf("Expected UMR\n"); 206 __msan_origin_tls = origin; 207 msan_expected_umr_found = 1; 208 return; 209 } 210 211 ++msan_report_count; 212 213 StackTrace stack; 214 GetStackTrace(&stack, kStackTraceMax, pc, bp, 215 common_flags()->fast_unwind_on_fatal); 216 217 u32 report_origin = 218 (__msan_get_track_origins() && OriginIsValid(origin)) ? origin : 0; 219 ReportUMR(&stack, report_origin); 220 221 if (__msan_get_track_origins() && !OriginIsValid(origin)) { 222 Printf( 223 " ORIGIN: invalid (%x). Might be a bug in MemorySanitizer origin " 224 "tracking.\n This could still be a bug in your code, too!\n", 225 origin); 226 } 227} 228 229void UnpoisonParam(uptr n) { 230 internal_memset(__msan_param_tls, 0, n * sizeof(*__msan_param_tls)); 231} 232 233// Backup MSan runtime TLS state. 234// Implementation must be async-signal-safe. 235// Instances of this class may live on the signal handler stack, and data size 236// may be an issue. 237void ScopedThreadLocalStateBackup::Backup() { 238 va_arg_overflow_size_tls = __msan_va_arg_overflow_size_tls; 239} 240 241void ScopedThreadLocalStateBackup::Restore() { 242 // A lame implementation that only keeps essential state and resets the rest. 243 __msan_va_arg_overflow_size_tls = va_arg_overflow_size_tls; 244 245 internal_memset(__msan_param_tls, 0, sizeof(__msan_param_tls)); 246 internal_memset(__msan_retval_tls, 0, sizeof(__msan_retval_tls)); 247 internal_memset(__msan_va_arg_tls, 0, sizeof(__msan_va_arg_tls)); 248 249 if (__msan_get_track_origins()) { 250 internal_memset(&__msan_retval_origin_tls, 0, sizeof(__msan_retval_tls)); 251 internal_memset(__msan_param_origin_tls, 0, 252 sizeof(__msan_param_origin_tls)); 253 } 254} 255 256void UnpoisonThreadLocalState() { 257} 258 259const char *GetOriginDescrIfStack(u32 id, uptr *pc) { 260 if ((id >> 31) == 0) return 0; 261 id &= (1U << 31) - 1; 262 CHECK_LT(id, kNumStackOriginDescrs); 263 if (pc) *pc = StackOriginPC[id]; 264 return StackOriginDescr[id]; 265} 266 267} // namespace __msan 268 269// Interface. 270 271using namespace __msan; 272 273void __msan_warning() { 274 GET_CALLER_PC_BP_SP; 275 (void)sp; 276 PrintWarning(pc, bp); 277 if (__msan::flags()->halt_on_error) { 278 Printf("Exiting\n"); 279 Die(); 280 } 281} 282 283void __msan_warning_noreturn() { 284 GET_CALLER_PC_BP_SP; 285 (void)sp; 286 PrintWarning(pc, bp); 287 Printf("Exiting\n"); 288 Die(); 289} 290 291void __msan_init() { 292 if (msan_inited) return; 293 msan_init_is_running = 1; 294 SanitizerToolName = "MemorySanitizer"; 295 296 SetDieCallback(MsanDie); 297 InitTlsSize(); 298 InitializeInterceptors(); 299 InstallAtExitHandler(); // Needs __cxa_atexit interceptor. 300 301 if (MSAN_REPLACE_OPERATORS_NEW_AND_DELETE) 302 ReplaceOperatorsNewAndDelete(); 303 const char *msan_options = GetEnv("MSAN_OPTIONS"); 304 InitializeFlags(&msan_flags, msan_options); 305 __sanitizer_set_report_path(common_flags()->log_path); 306 if (StackSizeIsUnlimited()) { 307 if (common_flags()->verbosity) 308 Printf("Unlimited stack, doing reexec\n"); 309 // A reasonably large stack size. It is bigger than the usual 8Mb, because, 310 // well, the program could have been run with unlimited stack for a reason. 311 SetStackSizeLimitInBytes(32 * 1024 * 1024); 312 ReExec(); 313 } 314 315 if (common_flags()->verbosity) 316 Printf("MSAN_OPTIONS: %s\n", msan_options ? msan_options : "<empty>"); 317 318 msan_running_under_dr = IsRunningUnderDr(); 319 __msan_clear_on_return(); 320 if (__msan_get_track_origins() && common_flags()->verbosity > 0) 321 Printf("msan_track_origins\n"); 322 if (!InitShadow(/* prot1 */ false, /* prot2 */ true, /* map_shadow */ true, 323 __msan_get_track_origins())) { 324 // FIXME: prot1 = false is only required when running under DR. 325 Printf("FATAL: MemorySanitizer can not mmap the shadow memory.\n"); 326 Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n"); 327 Printf("FATAL: Disabling ASLR is known to cause this error.\n"); 328 Printf("FATAL: If running under GDB, try " 329 "'set disable-randomization off'.\n"); 330 DumpProcessMap(); 331 Die(); 332 } 333 334 const char *external_symbolizer = common_flags()->external_symbolizer_path; 335 bool external_symbolizer_started = 336 Symbolizer::Init(external_symbolizer)->IsExternalAvailable(); 337 if (external_symbolizer && external_symbolizer[0]) { 338 CHECK(external_symbolizer_started); 339 } 340 Symbolizer::Get()->AddHooks(EnterSymbolizer, ExitSymbolizer); 341 342 GetThreadStackTopAndBottom(/* at_initialization */true, 343 &__msan_stack_bounds.stack_top, 344 &__msan_stack_bounds.stack_bottom); 345 if (common_flags()->verbosity) 346 Printf("MemorySanitizer init done\n"); 347 msan_init_is_running = 0; 348 msan_inited = 1; 349} 350 351void __msan_set_exit_code(int exit_code) { 352 flags()->exit_code = exit_code; 353} 354 355void __msan_set_keep_going(int keep_going) { 356 flags()->halt_on_error = !keep_going; 357} 358 359void __msan_set_expect_umr(int expect_umr) { 360 if (expect_umr) { 361 msan_expected_umr_found = 0; 362 } else if (!msan_expected_umr_found) { 363 GET_CALLER_PC_BP_SP; 364 (void)sp; 365 StackTrace stack; 366 GetStackTrace(&stack, kStackTraceMax, pc, bp, 367 common_flags()->fast_unwind_on_fatal); 368 ReportExpectedUMRNotFound(&stack); 369 Die(); 370 } 371 msan_expect_umr = expect_umr; 372} 373 374void __msan_print_shadow(const void *x, uptr size) { 375 unsigned char *s = (unsigned char*)MEM_TO_SHADOW(x); 376 u32 *o = (u32*)MEM_TO_ORIGIN(x); 377 for (uptr i = 0; i < size; i++) { 378 Printf("%x%x ", s[i] >> 4, s[i] & 0xf); 379 } 380 Printf("\n"); 381 if (__msan_get_track_origins()) { 382 for (uptr i = 0; i < size / 4; i++) { 383 Printf(" o: %x ", o[i]); 384 } 385 Printf("\n"); 386 } 387} 388 389void __msan_print_param_shadow() { 390 for (int i = 0; i < 16; i++) { 391 Printf("#%d:%zx ", i, __msan_param_tls[i]); 392 } 393 Printf("\n"); 394} 395 396sptr __msan_test_shadow(const void *x, uptr size) { 397 unsigned char *s = (unsigned char*)MEM_TO_SHADOW((uptr)x); 398 for (uptr i = 0; i < size; ++i) 399 if (s[i]) 400 return i; 401 return -1; 402} 403 404int __msan_set_poison_in_malloc(int do_poison) { 405 int old = flags()->poison_in_malloc; 406 flags()->poison_in_malloc = do_poison; 407 return old; 408} 409 410int __msan_has_dynamic_component() { 411 return msan_running_under_dr; 412} 413 414NOINLINE 415void __msan_clear_on_return() { 416 __msan_param_tls[0] = 0; 417} 418 419static void* get_tls_base() { 420 u64 p; 421 asm("mov %%fs:0, %0" 422 : "=r"(p) ::); 423 return (void*)p; 424} 425 426int __msan_get_retval_tls_offset() { 427 // volatile here is needed to avoid UB, because the compiler thinks that we 428 // are doing address arithmetics on unrelated pointers, and takes some 429 // shortcuts 430 volatile sptr retval_tls_p = (sptr)&__msan_retval_tls; 431 volatile sptr tls_base_p = (sptr)get_tls_base(); 432 return retval_tls_p - tls_base_p; 433} 434 435int __msan_get_param_tls_offset() { 436 // volatile here is needed to avoid UB, because the compiler thinks that we 437 // are doing address arithmetics on unrelated pointers, and takes some 438 // shortcuts 439 volatile sptr param_tls_p = (sptr)&__msan_param_tls; 440 volatile sptr tls_base_p = (sptr)get_tls_base(); 441 return param_tls_p - tls_base_p; 442} 443 444void __msan_partial_poison(const void* data, void* shadow, uptr size) { 445 internal_memcpy((void*)MEM_TO_SHADOW((uptr)data), shadow, size); 446} 447 448void __msan_load_unpoisoned(void *src, uptr size, void *dst) { 449 internal_memcpy(dst, src, size); 450 __msan_unpoison(dst, size); 451} 452 453void __msan_set_origin(const void *a, uptr size, u32 origin) { 454 // Origin mapping is 4 bytes per 4 bytes of application memory. 455 // Here we extend the range such that its left and right bounds are both 456 // 4 byte aligned. 457 if (!__msan_get_track_origins()) return; 458 uptr x = MEM_TO_ORIGIN((uptr)a); 459 uptr beg = x & ~3UL; // align down. 460 uptr end = (x + size + 3) & ~3UL; // align up. 461 u64 origin64 = ((u64)origin << 32) | origin; 462 // This is like memset, but the value is 32-bit. We unroll by 2 two write 463 // 64-bits at once. May want to unroll further to get 128-bit stores. 464 if (beg & 7ULL) { 465 *(u32*)beg = origin; 466 beg += 4; 467 } 468 for (uptr addr = beg; addr < (end & ~7UL); addr += 8) 469 *(u64*)addr = origin64; 470 if (end & 7ULL) 471 *(u32*)(end - 4) = origin; 472} 473 474// 'descr' is created at compile time and contains '----' in the beginning. 475// When we see descr for the first time we replace '----' with a uniq id 476// and set the origin to (id | (31-th bit)). 477void __msan_set_alloca_origin(void *a, uptr size, const char *descr) { 478 __msan_set_alloca_origin4(a, size, descr, 0); 479} 480 481void __msan_set_alloca_origin4(void *a, uptr size, const char *descr, uptr pc) { 482 static const u32 dash = '-'; 483 static const u32 first_timer = 484 dash + (dash << 8) + (dash << 16) + (dash << 24); 485 u32 *id_ptr = (u32*)descr; 486 bool print = false; // internal_strstr(descr + 4, "AllocaTOTest") != 0; 487 u32 id = *id_ptr; 488 if (id == first_timer) { 489 id = atomic_fetch_add(&NumStackOriginDescrs, 490 1, memory_order_relaxed); 491 *id_ptr = id; 492 CHECK_LT(id, kNumStackOriginDescrs); 493 StackOriginDescr[id] = descr + 4; 494 StackOriginPC[id] = pc; 495 if (print) 496 Printf("First time: id=%d %s %p \n", id, descr + 4, pc); 497 } 498 id |= 1U << 31; 499 if (print) 500 Printf("__msan_set_alloca_origin: descr=%s id=%x\n", descr + 4, id); 501 __msan_set_origin(a, size, id); 502} 503 504const char *__msan_get_origin_descr_if_stack(u32 id) { 505 return GetOriginDescrIfStack(id, 0); 506} 507 508u32 __msan_get_origin(const void *a) { 509 if (!__msan_get_track_origins()) return 0; 510 uptr x = (uptr)a; 511 uptr aligned = x & ~3ULL; 512 uptr origin_ptr = MEM_TO_ORIGIN(aligned); 513 return *(u32*)origin_ptr; 514} 515 516u32 __msan_get_umr_origin() { 517 return __msan_origin_tls; 518} 519 520u16 __sanitizer_unaligned_load16(const uu16 *p) { 521 __msan_retval_tls[0] = *(uu16 *)MEM_TO_SHADOW((uptr)p); 522 if (__msan_get_track_origins()) 523 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 524 return *p; 525} 526u32 __sanitizer_unaligned_load32(const uu32 *p) { 527 __msan_retval_tls[0] = *(uu32 *)MEM_TO_SHADOW((uptr)p); 528 if (__msan_get_track_origins()) 529 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 530 return *p; 531} 532u64 __sanitizer_unaligned_load64(const uu64 *p) { 533 __msan_retval_tls[0] = *(uu64 *)MEM_TO_SHADOW((uptr)p); 534 if (__msan_get_track_origins()) 535 __msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p); 536 return *p; 537} 538void __sanitizer_unaligned_store16(uu16 *p, u16 x) { 539 *(uu16 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 540 if (__msan_get_track_origins()) 541 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 542 *p = x; 543} 544void __sanitizer_unaligned_store32(uu32 *p, u32 x) { 545 *(uu32 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 546 if (__msan_get_track_origins()) 547 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 548 *p = x; 549} 550void __sanitizer_unaligned_store64(uu64 *p, u64 x) { 551 *(uu64 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1]; 552 if (__msan_get_track_origins()) 553 *(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1]; 554 *p = x; 555} 556 557#if !SANITIZER_SUPPORTS_WEAK_HOOKS 558extern "C" { 559SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE 560const char* __msan_default_options() { return ""; } 561} // extern "C" 562#endif 563 564