libsanitizer/ubsan/ubsan_diag.cpp

   1 //===-- ubsan_diag.cpp ----------------------------------------------------===//
   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 // Diagnostic reporting for the UBSan runtime.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "ubsan_platform.h"
  14 #if CAN_SANITIZE_UB
  15 #include "ubsan_diag.h"
  16 #include "ubsan_init.h"
  17 #include "ubsan_flags.h"
  18 #include "ubsan_monitor.h"
  19 #include "sanitizer_common/sanitizer_placement_new.h"
  20 #include "sanitizer_common/sanitizer_report_decorator.h"
  21 #include "sanitizer_common/sanitizer_stacktrace.h"
  22 #include "sanitizer_common/sanitizer_stacktrace_printer.h"
  23 #include "sanitizer_common/sanitizer_suppressions.h"
  24 #include "sanitizer_common/sanitizer_symbolizer.h"
  25 #include <stdio.h>
  26
  27 using namespace __ubsan;
  28
  29 // UBSan is combined with runtimes that already provide this functionality
  30 // (e.g., ASan) as well as runtimes that lack it (e.g., scudo). Tried to use
  31 // weak linkage to resolve this issue which is not portable and breaks on
  32 // Windows.
  33 // TODO(yln): This is a temporary workaround. GetStackTrace functions will be
  34 // removed in the future.
  35 void ubsan_GetStackTrace(BufferedStackTrace *stack, uptr max_depth, uptr pc,
  36                          uptr bp, void *context, bool request_fast) {
  37   uptr top = 0;
  38   uptr bottom = 0;
  39   GetThreadStackTopAndBottom(false, &top, &bottom);
  40   bool fast = StackTrace::WillUseFastUnwind(request_fast);
  41   stack->Unwind(max_depth, pc, bp, context, top, bottom, fast);
  42 }
  43
  44 static void MaybePrintStackTrace(uptr pc, uptr bp) {
  45   // We assume that flags are already parsed, as UBSan runtime
  46   // will definitely be called when we print the first diagnostics message.
  47   if (!flags()->print_stacktrace)
  48     return;
  49
  50   BufferedStackTrace stack;
  51   ubsan_GetStackTrace(&stack, kStackTraceMax, pc, bp, nullptr,
  52                 common_flags()->fast_unwind_on_fatal);
  53   stack.Print();
  54 }
  55
  56 static const char *ConvertTypeToString(ErrorType Type) {
  57   switch (Type) {
  58 #define UBSAN_CHECK(Name, SummaryKind, FSanitizeFlagName)                      \
  59   case ErrorType::Name:                                                        \
  60     return SummaryKind;
  61 #include "ubsan_checks.inc"
  62 #undef UBSAN_CHECK
  63   }
  64   UNREACHABLE("unknown ErrorType!");
  65 }
  66
  67 static const char *ConvertTypeToFlagName(ErrorType Type) {
  68   switch (Type) {
  69 #define UBSAN_CHECK(Name, SummaryKind, FSanitizeFlagName)                      \
  70   case ErrorType::Name:                                                        \
  71     return FSanitizeFlagName;
  72 #include "ubsan_checks.inc"
  73 #undef UBSAN_CHECK
  74   }
  75   UNREACHABLE("unknown ErrorType!");
  76 }
  77
  78 static void MaybeReportErrorSummary(Location Loc, ErrorType Type) {
  79   if (!common_flags()->print_summary)
  80     return;
  81   if (!flags()->report_error_type)
  82     Type = ErrorType::GenericUB;
  83   const char *ErrorKind = ConvertTypeToString(Type);
  84   if (Loc.isSourceLocation()) {
  85     SourceLocation SLoc = Loc.getSourceLocation();
  86     if (!SLoc.isInvalid()) {
  87       AddressInfo AI;
  88       AI.file = internal_strdup(SLoc.getFilename());
  89       AI.line = SLoc.getLine();
  90       AI.column = SLoc.getColumn();
  91       AI.function = internal_strdup("");  // Avoid printing ?? as function name.
  92       ReportErrorSummary(ErrorKind, AI, GetSanititizerToolName());
  93       AI.Clear();
  94       return;
  95     }
  96   } else if (Loc.isSymbolizedStack()) {
  97     const AddressInfo &AI = Loc.getSymbolizedStack()->info;
  98     ReportErrorSummary(ErrorKind, AI, GetSanititizerToolName());
  99     return;
 100   }
 101   ReportErrorSummary(ErrorKind, GetSanititizerToolName());
 102 }
 103
 104 namespace {
 105 class Decorator : public SanitizerCommonDecorator {
 106  public:
 107   Decorator() : SanitizerCommonDecorator() {}
 108   const char *Highlight() const { return Green(); }
 109   const char *Note() const { return Black(); }
 110 };
 111 }
 112
 113 SymbolizedStack *__ubsan::getSymbolizedLocation(uptr PC) {
 114   InitAsStandaloneIfNecessary();
 115   return Symbolizer::GetOrInit()->SymbolizePC(PC);
 116 }
 117
 118 Diag &Diag::operator<<(const TypeDescriptor &V) {
 119   return AddArg(V.getTypeName());
 120 }
 121
 122 Diag &Diag::operator<<(const Value &V) {
 123   if (V.getType().isSignedIntegerTy())
 124     AddArg(V.getSIntValue());
 125   else if (V.getType().isUnsignedIntegerTy())
 126     AddArg(V.getUIntValue());
 127   else if (V.getType().isFloatTy())
 128     AddArg(V.getFloatValue());
 129   else
 130     AddArg("<unknown>");
 131   return *this;
 132 }
 133
 134 /// Hexadecimal printing for numbers too large for Printf to handle directly.
 135 static void RenderHex(InternalScopedString *Buffer, UIntMax Val) {
 136 #if HAVE_INT128_T
 137   Buffer->append("0x%08x%08x%08x%08x", (unsigned int)(Val >> 96),
 138                  (unsigned int)(Val >> 64), (unsigned int)(Val >> 32),
 139                  (unsigned int)(Val));
 140 #else
 141   UNREACHABLE("long long smaller than 64 bits?");
 142 #endif
 143 }
 144
 145 static void RenderLocation(InternalScopedString *Buffer, Location Loc) {
 146   switch (Loc.getKind()) {
 147   case Location::LK_Source: {
 148     SourceLocation SLoc = Loc.getSourceLocation();
 149     if (SLoc.isInvalid())
 150       Buffer->append("<unknown>");
 151     else
 152       RenderSourceLocation(Buffer, SLoc.getFilename(), SLoc.getLine(),
 153                            SLoc.getColumn(), common_flags()->symbolize_vs_style,
 154                            common_flags()->strip_path_prefix);
 155     return;
 156   }
 157   case Location::LK_Memory:
 158     Buffer->append("%p", reinterpret_cast<void *>(Loc.getMemoryLocation()));
 159     return;
 160   case Location::LK_Symbolized: {
 161     const AddressInfo &Info = Loc.getSymbolizedStack()->info;
 162     if (Info.file)
 163       RenderSourceLocation(Buffer, Info.file, Info.line, Info.column,
 164                            common_flags()->symbolize_vs_style,
 165                            common_flags()->strip_path_prefix);
 166     else if (Info.module)
 167       RenderModuleLocation(Buffer, Info.module, Info.module_offset,
 168                            Info.module_arch, common_flags()->strip_path_prefix);
 169     else
 170       Buffer->append("%p", reinterpret_cast<void *>(Info.address));
 171     return;
 172   }
 173   case Location::LK_Null:
 174     Buffer->append("<unknown>");
 175     return;
 176   }
 177 }
 178
 179 static void RenderText(InternalScopedString *Buffer, const char *Message,
 180                        const Diag::Arg *Args) {
 181   for (const char *Msg = Message; *Msg; ++Msg) {
 182     if (*Msg != '%') {
 183       Buffer->append("%c", *Msg);
 184       continue;
 185     }
 186     const Diag::Arg &A = Args[*++Msg - '0'];
 187     switch (A.Kind) {
 188     case Diag::AK_String:
 189       Buffer->append("%s", A.String);
 190       break;
 191     case Diag::AK_TypeName: {
 192       if (SANITIZER_WINDOWS)
 193         // The Windows implementation demangles names early.
 194         Buffer->append("'%s'", A.String);
 195       else
 196         Buffer->append("'%s'", Symbolizer::GetOrInit()->Demangle(A.String));
 197       break;
 198     }
 199     case Diag::AK_SInt:
 200       // 'long long' is guaranteed to be at least 64 bits wide.
 201       if (A.SInt >= INT64_MIN && A.SInt <= INT64_MAX)
 202         Buffer->append("%lld", (long long)A.SInt);
 203       else
 204         RenderHex(Buffer, A.SInt);
 205       break;
 206     case Diag::AK_UInt:
 207       if (A.UInt <= UINT64_MAX)
 208         Buffer->append("%llu", (unsigned long long)A.UInt);
 209       else
 210         RenderHex(Buffer, A.UInt);
 211       break;
 212     case Diag::AK_Float: {
 213       // FIXME: Support floating-point formatting in sanitizer_common's
 214       //        printf, and stop using snprintf here.
 215       char FloatBuffer[32];
 216 #if SANITIZER_WINDOWS
 217       // On MSVC platforms, long doubles are equal to regular doubles.
 218       // In MinGW environments on x86, long doubles are 80 bit, but here,
 219       // we're calling an MS CRT provided printf function which considers
 220       // long doubles to be 64 bit. Just cast the float value to a regular
 221       // double to avoid the potential ambiguity in MinGW mode.
 222       sprintf_s(FloatBuffer, sizeof(FloatBuffer), "%g", (double)A.Float);
 223 #else
 224       snprintf(FloatBuffer, sizeof(FloatBuffer), "%Lg", (long double)A.Float);
 225 #endif
 226       Buffer->append("%s", FloatBuffer);
 227       break;
 228     }
 229     case Diag::AK_Pointer:
 230       Buffer->append("%p", A.Pointer);
 231       break;
 232     }
 233   }
 234 }
 235
 236 /// Find the earliest-starting range in Ranges which ends after Loc.
 237 static Range *upperBound(MemoryLocation Loc, Range *Ranges,
 238                          unsigned NumRanges) {
 239   Range *Best = 0;
 240   for (unsigned I = 0; I != NumRanges; ++I)
 241     if (Ranges[I].getEnd().getMemoryLocation() > Loc &&
 242         (!Best ||
 243          Best->getStart().getMemoryLocation() >
 244          Ranges[I].getStart().getMemoryLocation()))
 245       Best = &Ranges[I];
 246   return Best;
 247 }
 248
 249 static inline uptr subtractNoOverflow(uptr LHS, uptr RHS) {
 250   return (LHS < RHS) ? 0 : LHS - RHS;
 251 }
 252
 253 static inline uptr addNoOverflow(uptr LHS, uptr RHS) {
 254   const uptr Limit = (uptr)-1;
 255   return (LHS > Limit - RHS) ? Limit : LHS + RHS;
 256 }
 257
 258 /// Render a snippet of the address space near a location.
 259 static void PrintMemorySnippet(const Decorator &Decor, MemoryLocation Loc,
 260                                Range *Ranges, unsigned NumRanges,
 261                                const Diag::Arg *Args) {
 262   // Show at least the 8 bytes surrounding Loc.
 263   const unsigned MinBytesNearLoc = 4;
 264   MemoryLocation Min = subtractNoOverflow(Loc, MinBytesNearLoc);
 265   MemoryLocation Max = addNoOverflow(Loc, MinBytesNearLoc);
 266   MemoryLocation OrigMin = Min;
 267   for (unsigned I = 0; I < NumRanges; ++I) {
 268     Min = __sanitizer::Min(Ranges[I].getStart().getMemoryLocation(), Min);
 269     Max = __sanitizer::Max(Ranges[I].getEnd().getMemoryLocation(), Max);
 270   }
 271
 272   // If we have too many interesting bytes, prefer to show bytes after Loc.
 273   const unsigned BytesToShow = 32;
 274   if (Max - Min > BytesToShow)
 275     Min = __sanitizer::Min(Max - BytesToShow, OrigMin);
 276   Max = addNoOverflow(Min, BytesToShow);
 277
 278   if (!IsAccessibleMemoryRange(Min, Max - Min)) {
 279     Printf("<memory cannot be printed>\n");
 280     return;
 281   }
 282
 283   // Emit data.
 284   InternalScopedString Buffer;
 285   for (uptr P = Min; P != Max; ++P) {
 286     unsigned char C = *reinterpret_cast<const unsigned char*>(P);
 287     Buffer.append("%s%02x", (P % 8 == 0) ? "  " : " ", C);
 288   }
 289   Buffer.append("\n");
 290
 291   // Emit highlights.
 292   Buffer.append("%s", Decor.Highlight());
 293   Range *InRange = upperBound(Min, Ranges, NumRanges);
 294   for (uptr P = Min; P != Max; ++P) {
 295     char Pad = ' ', Byte = ' ';
 296     if (InRange && InRange->getEnd().getMemoryLocation() == P)
 297       InRange = upperBound(P, Ranges, NumRanges);
 298     if (!InRange && P > Loc)
 299       break;
 300     if (InRange && InRange->getStart().getMemoryLocation() < P)
 301       Pad = '~';
 302     if (InRange && InRange->getStart().getMemoryLocation() <= P)
 303       Byte = '~';
 304     if (P % 8 == 0)
 305       Buffer.append("%c", Pad);
 306     Buffer.append("%c", Pad);
 307     Buffer.append("%c", P == Loc ? '^' : Byte);
 308     Buffer.append("%c", Byte);
 309   }
 310   Buffer.append("%s\n", Decor.Default());
 311
 312   // Go over the line again, and print names for the ranges.
 313   InRange = 0;
 314   unsigned Spaces = 0;
 315   for (uptr P = Min; P != Max; ++P) {
 316     if (!InRange || InRange->getEnd().getMemoryLocation() == P)
 317       InRange = upperBound(P, Ranges, NumRanges);
 318     if (!InRange)
 319       break;
 320
 321     Spaces += (P % 8) == 0 ? 2 : 1;
 322
 323     if (InRange && InRange->getStart().getMemoryLocation() == P) {
 324       while (Spaces--)
 325         Buffer.append(" ");
 326       RenderText(&Buffer, InRange->getText(), Args);
 327       Buffer.append("\n");
 328       // FIXME: We only support naming one range for now!
 329       break;
 330     }
 331
 332     Spaces += 2;
 333   }
 334
 335   Printf("%s", Buffer.data());
 336   // FIXME: Print names for anything we can identify within the line:
 337   //
 338   //  * If we can identify the memory itself as belonging to a particular
 339   //    global, stack variable, or dynamic allocation, then do so.
 340   //
 341   //  * If we have a pointer-size, pointer-aligned range highlighted,
 342   //    determine whether the value of that range is a pointer to an
 343   //    entity which we can name, and if so, print that name.
 344   //
 345   // This needs an external symbolizer, or (preferably) ASan instrumentation.
 346 }
 347
 348 Diag::~Diag() {
 349   // All diagnostics should be printed under report mutex.
 350   ScopedReport::CheckLocked();
 351   Decorator Decor;
 352   InternalScopedString Buffer;
 353
 354   // Prepare a report that a monitor process can inspect.
 355   if (Level == DL_Error) {
 356     RenderText(&Buffer, Message, Args);
 357     UndefinedBehaviorReport UBR{ConvertTypeToString(ET), Loc, Buffer};
 358     Buffer.clear();
 359   }
 360
 361   Buffer.append("%s", Decor.Bold());
 362   RenderLocation(&Buffer, Loc);
 363   Buffer.append(":");
 364
 365   switch (Level) {
 366   case DL_Error:
 367     Buffer.append("%s runtime error: %s%s", Decor.Warning(), Decor.Default(),
 368                   Decor.Bold());
 369     break;
 370
 371   case DL_Note:
 372     Buffer.append("%s note: %s", Decor.Note(), Decor.Default());
 373     break;
 374   }
 375
 376   RenderText(&Buffer, Message, Args);
 377
 378   Buffer.append("%s\n", Decor.Default());
 379   Printf("%s", Buffer.data());
 380
 381   if (Loc.isMemoryLocation())
 382     PrintMemorySnippet(Decor, Loc.getMemoryLocation(), Ranges, NumRanges, Args);
 383 }
 384
 385 ScopedReport::Initializer::Initializer() { InitAsStandaloneIfNecessary(); }
 386
 387 ScopedReport::ScopedReport(ReportOptions Opts, Location SummaryLoc,
 388                            ErrorType Type)
 389     : Opts(Opts), SummaryLoc(SummaryLoc), Type(Type) {}
 390
 391 ScopedReport::~ScopedReport() {
 392   MaybePrintStackTrace(Opts.pc, Opts.bp);
 393   MaybeReportErrorSummary(SummaryLoc, Type);
 394
 395   if (common_flags()->print_module_map >= 2)
 396     DumpProcessMap();
 397
 398   if (flags()->halt_on_error)
 399     Die();
 400 }
 401
 402 ALIGNED(64) static char suppression_placeholder[sizeof(SuppressionContext)];
 403 static SuppressionContext *suppression_ctx = nullptr;
 404 static const char kVptrCheck[] = "vptr_check";
 405 static const char *kSuppressionTypes[] = {
 406 #define UBSAN_CHECK(Name, SummaryKind, FSanitizeFlagName) FSanitizeFlagName,
 407 #include "ubsan_checks.inc"
 408 #undef UBSAN_CHECK
 409     kVptrCheck,
 410 };
 411
 412 void __ubsan::InitializeSuppressions() {
 413   CHECK_EQ(nullptr, suppression_ctx);
 414   suppression_ctx = new (suppression_placeholder)
 415       SuppressionContext(kSuppressionTypes, ARRAY_SIZE(kSuppressionTypes));
 416   suppression_ctx->ParseFromFile(flags()->suppressions);
 417 }
 418
 419 bool __ubsan::IsVptrCheckSuppressed(const char *TypeName) {
 420   InitAsStandaloneIfNecessary();
 421   CHECK(suppression_ctx);
 422   Suppression *s;
 423   return suppression_ctx->Match(TypeName, kVptrCheck, &s);
 424 }
 425
 426 bool __ubsan::IsPCSuppressed(ErrorType ET, uptr PC, const char *Filename) {
 427   InitAsStandaloneIfNecessary();
 428   CHECK(suppression_ctx);
 429   const char *SuppType = ConvertTypeToFlagName(ET);
 430   // Fast path: don't symbolize PC if there is no suppressions for given UB
 431   // type.
 432   if (!suppression_ctx->HasSuppressionType(SuppType))
 433     return false;
 434   Suppression *s = nullptr;
 435   // Suppress by file name known to runtime.
 436   if (Filename != nullptr && suppression_ctx->Match(Filename, SuppType, &s))
 437     return true;
 438   // Suppress by module name.
 439   if (const char *Module = Symbolizer::GetOrInit()->GetModuleNameForPc(PC)) {
 440     if (suppression_ctx->Match(Module, SuppType, &s))
 441       return true;
 442   }
 443   // Suppress by function or source file name from debug info.
 444   SymbolizedStackHolder Stack(Symbolizer::GetOrInit()->SymbolizePC(PC));
 445   const AddressInfo &AI = Stack.get()->info;
 446   return suppression_ctx->Match(AI.function, SuppType, &s) ||
 447          suppression_ctx->Match(AI.file, SuppType, &s);
 448 }
 449
 450 #endif  // CAN_SANITIZE_UB