libsanitizer/asan/asan_descriptions.cpp

   1 //===-- asan_descriptions.cpp -----------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of AddressSanitizer, an address sanity checker.
  10 //
  11 // ASan functions for getting information about an address and/or printing it.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "asan_descriptions.h"
  15 #include "asan_mapping.h"
  16 #include "asan_report.h"
  17 #include "asan_stack.h"
  18 #include "sanitizer_common/sanitizer_stackdepot.h"
  19
  20 namespace __asan {
  21
  22 AsanThreadIdAndName::AsanThreadIdAndName(AsanThreadContext *t) {
  23   Init(t->tid, t->name);
  24 }
  25
  26 AsanThreadIdAndName::AsanThreadIdAndName(u32 tid) {
  27   if (tid == kInvalidTid) {
  28     Init(tid, "");
  29   } else {
  30     asanThreadRegistry().CheckLocked();
  31     AsanThreadContext *t = GetThreadContextByTidLocked(tid);
  32     Init(tid, t->name);
  33   }
  34 }
  35
  36 void AsanThreadIdAndName::Init(u32 tid, const char *tname) {
  37   int len = internal_snprintf(name, sizeof(name), "T%d", tid);
  38   CHECK(((unsigned int)len) < sizeof(name));
  39   if (tname[0] != '\0')
  40     internal_snprintf(&name[len], sizeof(name) - len, " (%s)", tname);
  41 }
  42
  43 void DescribeThread(AsanThreadContext *context) {
  44   CHECK(context);
  45   asanThreadRegistry().CheckLocked();
  46   // No need to announce the main thread.
  47   if (context->tid == kMainTid || context->announced) {
  48     return;
  49   }
  50   context->announced = true;
  51   InternalScopedString str;
  52   str.append("Thread %s", AsanThreadIdAndName(context).c_str());
  53   if (context->parent_tid == kInvalidTid) {
  54     str.append(" created by unknown thread\n");
  55     Printf("%s", str.data());
  56     return;
  57   }
  58   str.append(" created by %s here:\n",
  59              AsanThreadIdAndName(context->parent_tid).c_str());
  60   Printf("%s", str.data());
  61   StackDepotGet(context->stack_id).Print();
  62   // Recursively described parent thread if needed.
  63   if (flags()->print_full_thread_history) {
  64     AsanThreadContext *parent_context =
  65         GetThreadContextByTidLocked(context->parent_tid);
  66     DescribeThread(parent_context);
  67   }
  68 }
  69
  70 // Shadow descriptions
  71 static bool GetShadowKind(uptr addr, ShadowKind *shadow_kind) {
  72   CHECK(!AddrIsInMem(addr));
  73   if (AddrIsInShadowGap(addr)) {
  74     *shadow_kind = kShadowKindGap;
  75   } else if (AddrIsInHighShadow(addr)) {
  76     *shadow_kind = kShadowKindHigh;
  77   } else if (AddrIsInLowShadow(addr)) {
  78     *shadow_kind = kShadowKindLow;
  79   } else {
  80     return false;
  81   }
  82   return true;
  83 }
  84
  85 bool DescribeAddressIfShadow(uptr addr) {
  86   ShadowAddressDescription descr;
  87   if (!GetShadowAddressInformation(addr, &descr)) return false;
  88   descr.Print();
  89   return true;
  90 }
  91
  92 bool GetShadowAddressInformation(uptr addr, ShadowAddressDescription *descr) {
  93   if (AddrIsInMem(addr)) return false;
  94   ShadowKind shadow_kind;
  95   if (!GetShadowKind(addr, &shadow_kind)) return false;
  96   if (shadow_kind != kShadowKindGap) descr->shadow_byte = *(u8 *)addr;
  97   descr->addr = addr;
  98   descr->kind = shadow_kind;
  99   return true;
 100 }
 101
 102 // Heap descriptions
 103 static void GetAccessToHeapChunkInformation(ChunkAccess *descr,
 104                                             AsanChunkView chunk, uptr addr,
 105                                             uptr access_size) {
 106   descr->bad_addr = addr;
 107   if (chunk.AddrIsAtLeft(addr, access_size, &descr->offset)) {
 108     descr->access_type = kAccessTypeLeft;
 109   } else if (chunk.AddrIsAtRight(addr, access_size, &descr->offset)) {
 110     descr->access_type = kAccessTypeRight;
 111     if (descr->offset < 0) {
 112       descr->bad_addr -= descr->offset;
 113       descr->offset = 0;
 114     }
 115   } else if (chunk.AddrIsInside(addr, access_size, &descr->offset)) {
 116     descr->access_type = kAccessTypeInside;
 117   } else {
 118     descr->access_type = kAccessTypeUnknown;
 119   }
 120   descr->chunk_begin = chunk.Beg();
 121   descr->chunk_size = chunk.UsedSize();
 122   descr->user_requested_alignment = chunk.UserRequestedAlignment();
 123   descr->alloc_type = chunk.GetAllocType();
 124 }
 125
 126 static void PrintHeapChunkAccess(uptr addr, const ChunkAccess &descr) {
 127   Decorator d;
 128   InternalScopedString str;
 129   str.append("%s", d.Location());
 130   switch (descr.access_type) {
 131     case kAccessTypeLeft:
 132       str.append("%p is located %zd bytes before",
 133                  (void *)descr.bad_addr, descr.offset);
 134       break;
 135     case kAccessTypeRight:
 136       str.append("%p is located %zd bytes after",
 137                  (void *)descr.bad_addr, descr.offset);
 138       break;
 139     case kAccessTypeInside:
 140       str.append("%p is located %zd bytes inside of", (void *)descr.bad_addr,
 141                  descr.offset);
 142       break;
 143     case kAccessTypeUnknown:
 144       str.append(
 145           "%p is located somewhere around (this is AddressSanitizer bug!)",
 146           (void *)descr.bad_addr);
 147   }
 148   str.append(" %zu-byte region [%p,%p)\n", descr.chunk_size,
 149              (void *)descr.chunk_begin,
 150              (void *)(descr.chunk_begin + descr.chunk_size));
 151   str.append("%s", d.Default());
 152   Printf("%s", str.data());
 153 }
 154
 155 bool GetHeapAddressInformation(uptr addr, uptr access_size,
 156                                HeapAddressDescription *descr) {
 157   AsanChunkView chunk = FindHeapChunkByAddress(addr);
 158   if (!chunk.IsValid()) {
 159     return false;
 160   }
 161   descr->addr = addr;
 162   GetAccessToHeapChunkInformation(&descr->chunk_access, chunk, addr,
 163                                   access_size);
 164   CHECK_NE(chunk.AllocTid(), kInvalidTid);
 165   descr->alloc_tid = chunk.AllocTid();
 166   descr->alloc_stack_id = chunk.GetAllocStackId();
 167   descr->free_tid = chunk.FreeTid();
 168   if (descr->free_tid != kInvalidTid)
 169     descr->free_stack_id = chunk.GetFreeStackId();
 170   return true;
 171 }
 172
 173 static StackTrace GetStackTraceFromId(u32 id) {
 174   CHECK(id);
 175   StackTrace res = StackDepotGet(id);
 176   CHECK(res.trace);
 177   return res;
 178 }
 179
 180 bool DescribeAddressIfHeap(uptr addr, uptr access_size) {
 181   HeapAddressDescription descr;
 182   if (!GetHeapAddressInformation(addr, access_size, &descr)) {
 183     Printf(
 184         "AddressSanitizer can not describe address in more detail "
 185         "(wild memory access suspected).\n");
 186     return false;
 187   }
 188   descr.Print();
 189   return true;
 190 }
 191
 192 // Stack descriptions
 193 bool GetStackAddressInformation(uptr addr, uptr access_size,
 194                                 StackAddressDescription *descr) {
 195   AsanThread *t = FindThreadByStackAddress(addr);
 196   if (!t) return false;
 197
 198   descr->addr = addr;
 199   descr->tid = t->tid();
 200   // Try to fetch precise stack frame for this access.
 201   AsanThread::StackFrameAccess access;
 202   if (!t->GetStackFrameAccessByAddr(addr, &access)) {
 203     descr->frame_descr = nullptr;
 204     return true;
 205   }
 206
 207   descr->offset = access.offset;
 208   descr->access_size = access_size;
 209   descr->frame_pc = access.frame_pc;
 210   descr->frame_descr = access.frame_descr;
 211
 212 #if SANITIZER_PPC64V1
 213   // On PowerPC64 ELFv1, the address of a function actually points to a
 214   // three-doubleword data structure with the first field containing
 215   // the address of the function's code.
 216   descr->frame_pc = *reinterpret_cast<uptr *>(descr->frame_pc);
 217 #endif
 218   descr->frame_pc += 16;
 219
 220   return true;
 221 }
 222
 223 static void PrintAccessAndVarIntersection(const StackVarDescr &var, uptr addr,
 224                                           uptr access_size, uptr prev_var_end,
 225                                           uptr next_var_beg) {
 226   uptr var_end = var.beg + var.size;
 227   uptr addr_end = addr + access_size;
 228   const char *pos_descr = nullptr;
 229   // If the variable [var.beg, var_end) is the nearest variable to the
 230   // current memory access, indicate it in the log.
 231   if (addr >= var.beg) {
 232     if (addr_end <= var_end)
 233       pos_descr = "is inside";  // May happen if this is a use-after-return.
 234     else if (addr < var_end)
 235       pos_descr = "partially overflows";
 236     else if (addr_end <= next_var_beg &&
 237              next_var_beg - addr_end >= addr - var_end)
 238       pos_descr = "overflows";
 239   } else {
 240     if (addr_end > var.beg)
 241       pos_descr = "partially underflows";
 242     else if (addr >= prev_var_end && addr - prev_var_end >= var.beg - addr_end)
 243       pos_descr = "underflows";
 244   }
 245   InternalScopedString str;
 246   str.append("    [%zd, %zd)", var.beg, var_end);
 247   // Render variable name.
 248   str.append(" '");
 249   for (uptr i = 0; i < var.name_len; ++i) {
 250     str.append("%c", var.name_pos[i]);
 251   }
 252   str.append("'");
 253   if (var.line > 0) {
 254     str.append(" (line %zd)", var.line);
 255   }
 256   if (pos_descr) {
 257     Decorator d;
 258     // FIXME: we may want to also print the size of the access here,
 259     // but in case of accesses generated by memset it may be confusing.
 260     str.append("%s <== Memory access at offset %zd %s this variable%s\n",
 261                d.Location(), addr, pos_descr, d.Default());
 262   } else {
 263     str.append("\n");
 264   }
 265   Printf("%s", str.data());
 266 }
 267
 268 bool DescribeAddressIfStack(uptr addr, uptr access_size) {
 269   StackAddressDescription descr;
 270   if (!GetStackAddressInformation(addr, access_size, &descr)) return false;
 271   descr.Print();
 272   return true;
 273 }
 274
 275 // Global descriptions
 276 static void DescribeAddressRelativeToGlobal(uptr addr, uptr access_size,
 277                                             const __asan_global &g) {
 278   InternalScopedString str;
 279   Decorator d;
 280   str.append("%s", d.Location());
 281   if (addr < g.beg) {
 282     str.append("%p is located %zd bytes before", (void *)addr,
 283                g.beg - addr);
 284   } else if (addr + access_size > g.beg + g.size) {
 285     if (addr < g.beg + g.size) addr = g.beg + g.size;
 286     str.append("%p is located %zd bytes after", (void *)addr,
 287                addr - (g.beg + g.size));
 288   } else {
 289     // Can it happen?
 290     str.append("%p is located %zd bytes inside of", (void *)addr, addr - g.beg);
 291   }
 292   str.append(" global variable '%s' defined in '",
 293              MaybeDemangleGlobalName(g.name));
 294   PrintGlobalLocation(&str, g);
 295   str.append("' (0x%zx) of size %zu\n", g.beg, g.size);
 296   str.append("%s", d.Default());
 297   PrintGlobalNameIfASCII(&str, g);
 298   Printf("%s", str.data());
 299 }
 300
 301 bool GetGlobalAddressInformation(uptr addr, uptr access_size,
 302                                  GlobalAddressDescription *descr) {
 303   descr->addr = addr;
 304   int globals_num = GetGlobalsForAddress(addr, descr->globals, descr->reg_sites,
 305                                          ARRAY_SIZE(descr->globals));
 306   descr->size = globals_num;
 307   descr->access_size = access_size;
 308   return globals_num != 0;
 309 }
 310
 311 bool DescribeAddressIfGlobal(uptr addr, uptr access_size,
 312                              const char *bug_type) {
 313   GlobalAddressDescription descr;
 314   if (!GetGlobalAddressInformation(addr, access_size, &descr)) return false;
 315
 316   descr.Print(bug_type);
 317   return true;
 318 }
 319
 320 void ShadowAddressDescription::Print() const {
 321   Printf("Address %p is located in the %s area.\n", (void *)addr,
 322          ShadowNames[kind]);
 323 }
 324
 325 void GlobalAddressDescription::Print(const char *bug_type) const {
 326   for (int i = 0; i < size; i++) {
 327     DescribeAddressRelativeToGlobal(addr, access_size, globals[i]);
 328     if (bug_type &&
 329         0 == internal_strcmp(bug_type, "initialization-order-fiasco") &&
 330         reg_sites[i]) {
 331       Printf("  registered at:\n");
 332       StackDepotGet(reg_sites[i]).Print();
 333     }
 334   }
 335 }
 336
 337 bool GlobalAddressDescription::PointsInsideTheSameVariable(
 338     const GlobalAddressDescription &other) const {
 339   if (size == 0 || other.size == 0) return false;
 340
 341   for (uptr i = 0; i < size; i++) {
 342     const __asan_global &a = globals[i];
 343     for (uptr j = 0; j < other.size; j++) {
 344       const __asan_global &b = other.globals[j];
 345       if (a.beg == b.beg &&
 346           a.beg <= addr &&
 347           b.beg <= other.addr &&
 348           (addr + access_size) < (a.beg + a.size) &&
 349           (other.addr + other.access_size) < (b.beg + b.size))
 350         return true;
 351     }
 352   }
 353
 354   return false;
 355 }
 356
 357 void StackAddressDescription::Print() const {
 358   Decorator d;
 359   Printf("%s", d.Location());
 360   Printf("Address %p is located in stack of thread %s", (void *)addr,
 361          AsanThreadIdAndName(tid).c_str());
 362
 363   if (!frame_descr) {
 364     Printf("%s\n", d.Default());
 365     return;
 366   }
 367   Printf(" at offset %zu in frame%s\n", offset, d.Default());
 368
 369   // Now we print the frame where the alloca has happened.
 370   // We print this frame as a stack trace with one element.
 371   // The symbolizer may print more than one frame if inlining was involved.
 372   // The frame numbers may be different than those in the stack trace printed
 373   // previously. That's unfortunate, but I have no better solution,
 374   // especially given that the alloca may be from entirely different place
 375   // (e.g. use-after-scope, or different thread's stack).
 376   Printf("%s", d.Default());
 377   StackTrace alloca_stack(&frame_pc, 1);
 378   alloca_stack.Print();
 379
 380   InternalMmapVector<StackVarDescr> vars;
 381   vars.reserve(16);
 382   if (!ParseFrameDescription(frame_descr, &vars)) {
 383     Printf(
 384         "AddressSanitizer can't parse the stack frame "
 385         "descriptor: |%s|\n",
 386         frame_descr);
 387     // 'addr' is a stack address, so return true even if we can't parse frame
 388     return;
 389   }
 390   uptr n_objects = vars.size();
 391   // Report the number of stack objects.
 392   Printf("  This frame has %zu object(s):\n", n_objects);
 393
 394   // Report all objects in this frame.
 395   for (uptr i = 0; i < n_objects; i++) {
 396     uptr prev_var_end = i ? vars[i - 1].beg + vars[i - 1].size : 0;
 397     uptr next_var_beg = i + 1 < n_objects ? vars[i + 1].beg : ~(0UL);
 398     PrintAccessAndVarIntersection(vars[i], offset, access_size, prev_var_end,
 399                                   next_var_beg);
 400   }
 401   Printf(
 402       "HINT: this may be a false positive if your program uses "
 403       "some custom stack unwind mechanism, swapcontext or vfork\n");
 404   if (SANITIZER_WINDOWS)
 405     Printf("      (longjmp, SEH and C++ exceptions *are* supported)\n");
 406   else
 407     Printf("      (longjmp and C++ exceptions *are* supported)\n");
 408
 409   DescribeThread(GetThreadContextByTidLocked(tid));
 410 }
 411
 412 void HeapAddressDescription::Print() const {
 413   PrintHeapChunkAccess(addr, chunk_access);
 414
 415   asanThreadRegistry().CheckLocked();
 416   AsanThreadContext *alloc_thread = GetThreadContextByTidLocked(alloc_tid);
 417   StackTrace alloc_stack = GetStackTraceFromId(alloc_stack_id);
 418
 419   Decorator d;
 420   AsanThreadContext *free_thread = nullptr;
 421   if (free_tid != kInvalidTid) {
 422     free_thread = GetThreadContextByTidLocked(free_tid);
 423     Printf("%sfreed by thread %s here:%s\n", d.Allocation(),
 424            AsanThreadIdAndName(free_thread).c_str(), d.Default());
 425     StackTrace free_stack = GetStackTraceFromId(free_stack_id);
 426     free_stack.Print();
 427     Printf("%spreviously allocated by thread %s here:%s\n", d.Allocation(),
 428            AsanThreadIdAndName(alloc_thread).c_str(), d.Default());
 429   } else {
 430     Printf("%sallocated by thread %s here:%s\n", d.Allocation(),
 431            AsanThreadIdAndName(alloc_thread).c_str(), d.Default());
 432   }
 433   alloc_stack.Print();
 434   DescribeThread(GetCurrentThread());
 435   if (free_thread) DescribeThread(free_thread);
 436   DescribeThread(alloc_thread);
 437 }
 438
 439 AddressDescription::AddressDescription(uptr addr, uptr access_size,
 440                                        bool shouldLockThreadRegistry) {
 441   if (GetShadowAddressInformation(addr, &data.shadow)) {
 442     data.kind = kAddressKindShadow;
 443     return;
 444   }
 445   if (GetHeapAddressInformation(addr, access_size, &data.heap)) {
 446     data.kind = kAddressKindHeap;
 447     return;
 448   }
 449
 450   bool isStackMemory = false;
 451   if (shouldLockThreadRegistry) {
 452     ThreadRegistryLock l(&asanThreadRegistry());
 453     isStackMemory = GetStackAddressInformation(addr, access_size, &data.stack);
 454   } else {
 455     isStackMemory = GetStackAddressInformation(addr, access_size, &data.stack);
 456   }
 457   if (isStackMemory) {
 458     data.kind = kAddressKindStack;
 459     return;
 460   }
 461
 462   if (GetGlobalAddressInformation(addr, access_size, &data.global)) {
 463     data.kind = kAddressKindGlobal;
 464     return;
 465   }
 466   data.kind = kAddressKindWild;
 467   data.wild.addr = addr;
 468   data.wild.access_size = access_size;
 469 }
 470
 471 void WildAddressDescription::Print() const {
 472   Printf("Address %p is a wild pointer inside of access range of size %p.\n",
 473          (void *)addr, (void *)access_size);
 474 }
 475
 476 void PrintAddressDescription(uptr addr, uptr access_size,
 477                              const char *bug_type) {
 478   ShadowAddressDescription shadow_descr;
 479   if (GetShadowAddressInformation(addr, &shadow_descr)) {
 480     shadow_descr.Print();
 481     return;
 482   }
 483
 484   GlobalAddressDescription global_descr;
 485   if (GetGlobalAddressInformation(addr, access_size, &global_descr)) {
 486     global_descr.Print(bug_type);
 487     return;
 488   }
 489
 490   StackAddressDescription stack_descr;
 491   if (GetStackAddressInformation(addr, access_size, &stack_descr)) {
 492     stack_descr.Print();
 493     return;
 494   }
 495
 496   HeapAddressDescription heap_descr;
 497   if (GetHeapAddressInformation(addr, access_size, &heap_descr)) {
 498     heap_descr.Print();
 499     return;
 500   }
 501
 502   // We exhausted our possibilities. Bail out.
 503   Printf(
 504       "AddressSanitizer can not describe address in more detail "
 505       "(wild memory access suspected).\n");
 506 }
 507 }  // namespace __asan