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       sprintf_s(FloatBuffer, sizeof(FloatBuffer), "%Lg", (long double)A.Float);
 218 #else
 219       snprintf(FloatBuffer, sizeof(FloatBuffer), "%Lg", (long double)A.Float);
 220 #endif
 221       Buffer->append("%s", FloatBuffer);
 222       break;
 223     }
 224     case Diag::AK_Pointer:
 225       Buffer->append("%p", A.Pointer);
 226       break;
 227     }
 228   }
 229 }
 230
 231 /// Find the earliest-starting range in Ranges which ends after Loc.
 232 static Range *upperBound(MemoryLocation Loc, Range *Ranges,
 233                          unsigned NumRanges) {
 234   Range *Best = 0;
 235   for (unsigned I = 0; I != NumRanges; ++I)
 236     if (Ranges[I].getEnd().getMemoryLocation() > Loc &&
 237         (!Best ||
 238          Best->getStart().getMemoryLocation() >
 239          Ranges[I].getStart().getMemoryLocation()))
 240       Best = &Ranges[I];
 241   return Best;
 242 }
 243
 244 static inline uptr subtractNoOverflow(uptr LHS, uptr RHS) {
 245   return (LHS < RHS) ? 0 : LHS - RHS;
 246 }
 247
 248 static inline uptr addNoOverflow(uptr LHS, uptr RHS) {
 249   const uptr Limit = (uptr)-1;
 250   return (LHS > Limit - RHS) ? Limit : LHS + RHS;
 251 }
 252
 253 /// Render a snippet of the address space near a location.
 254 static void PrintMemorySnippet(const Decorator &Decor, MemoryLocation Loc,
 255                                Range *Ranges, unsigned NumRanges,
 256                                const Diag::Arg *Args) {
 257   // Show at least the 8 bytes surrounding Loc.
 258   const unsigned MinBytesNearLoc = 4;
 259   MemoryLocation Min = subtractNoOverflow(Loc, MinBytesNearLoc);
 260   MemoryLocation Max = addNoOverflow(Loc, MinBytesNearLoc);
 261   MemoryLocation OrigMin = Min;
 262   for (unsigned I = 0; I < NumRanges; ++I) {
 263     Min = __sanitizer::Min(Ranges[I].getStart().getMemoryLocation(), Min);
 264     Max = __sanitizer::Max(Ranges[I].getEnd().getMemoryLocation(), Max);
 265   }
 266
 267   // If we have too many interesting bytes, prefer to show bytes after Loc.
 268   const unsigned BytesToShow = 32;
 269   if (Max - Min > BytesToShow)
 270     Min = __sanitizer::Min(Max - BytesToShow, OrigMin);
 271   Max = addNoOverflow(Min, BytesToShow);
 272
 273   if (!IsAccessibleMemoryRange(Min, Max - Min)) {
 274     Printf("<memory cannot be printed>\n");
 275     return;
 276   }
 277
 278   // Emit data.
 279   InternalScopedString Buffer;
 280   for (uptr P = Min; P != Max; ++P) {
 281     unsigned char C = *reinterpret_cast<const unsigned char*>(P);
 282     Buffer.append("%s%02x", (P % 8 == 0) ? "  " : " ", C);
 283   }
 284   Buffer.append("\n");
 285
 286   // Emit highlights.
 287   Buffer.append("%s", Decor.Highlight());
 288   Range *InRange = upperBound(Min, Ranges, NumRanges);
 289   for (uptr P = Min; P != Max; ++P) {
 290     char Pad = ' ', Byte = ' ';
 291     if (InRange && InRange->getEnd().getMemoryLocation() == P)
 292       InRange = upperBound(P, Ranges, NumRanges);
 293     if (!InRange && P > Loc)
 294       break;
 295     if (InRange && InRange->getStart().getMemoryLocation() < P)
 296       Pad = '~';
 297     if (InRange && InRange->getStart().getMemoryLocation() <= P)
 298       Byte = '~';
 299     if (P % 8 == 0)
 300       Buffer.append("%c", Pad);
 301     Buffer.append("%c", Pad);
 302     Buffer.append("%c", P == Loc ? '^' : Byte);
 303     Buffer.append("%c", Byte);
 304   }
 305   Buffer.append("%s\n", Decor.Default());
 306
 307   // Go over the line again, and print names for the ranges.
 308   InRange = 0;
 309   unsigned Spaces = 0;
 310   for (uptr P = Min; P != Max; ++P) {
 311     if (!InRange || InRange->getEnd().getMemoryLocation() == P)
 312       InRange = upperBound(P, Ranges, NumRanges);
 313     if (!InRange)
 314       break;
 315
 316     Spaces += (P % 8) == 0 ? 2 : 1;
 317
 318     if (InRange && InRange->getStart().getMemoryLocation() == P) {
 319       while (Spaces--)
 320         Buffer.append(" ");
 321       RenderText(&Buffer, InRange->getText(), Args);
 322       Buffer.append("\n");
 323       // FIXME: We only support naming one range for now!
 324       break;
 325     }
 326
 327     Spaces += 2;
 328   }
 329
 330   Printf("%s", Buffer.data());
 331   // FIXME: Print names for anything we can identify within the line:
 332   //
 333   //  * If we can identify the memory itself as belonging to a particular
 334   //    global, stack variable, or dynamic allocation, then do so.
 335   //
 336   //  * If we have a pointer-size, pointer-aligned range highlighted,
 337   //    determine whether the value of that range is a pointer to an
 338   //    entity which we can name, and if so, print that name.
 339   //
 340   // This needs an external symbolizer, or (preferably) ASan instrumentation.
 341 }
 342
 343 Diag::~Diag() {
 344   // All diagnostics should be printed under report mutex.
 345   ScopedReport::CheckLocked();
 346   Decorator Decor;
 347   InternalScopedString Buffer;
 348
 349   // Prepare a report that a monitor process can inspect.
 350   if (Level == DL_Error) {
 351     RenderText(&Buffer, Message, Args);
 352     UndefinedBehaviorReport UBR{ConvertTypeToString(ET), Loc, Buffer};
 353     Buffer.clear();
 354   }
 355
 356   Buffer.append("%s", Decor.Bold());
 357   RenderLocation(&Buffer, Loc);
 358   Buffer.append(":");
 359
 360   switch (Level) {
 361   case DL_Error:
 362     Buffer.append("%s runtime error: %s%s", Decor.Warning(), Decor.Default(),
 363                   Decor.Bold());
 364     break;
 365
 366   case DL_Note:
 367     Buffer.append("%s note: %s", Decor.Note(), Decor.Default());
 368     break;
 369   }
 370
 371   RenderText(&Buffer, Message, Args);
 372
 373   Buffer.append("%s\n", Decor.Default());
 374   Printf("%s", Buffer.data());
 375
 376   if (Loc.isMemoryLocation())
 377     PrintMemorySnippet(Decor, Loc.getMemoryLocation(), Ranges, NumRanges, Args);
 378 }
 379
 380 ScopedReport::Initializer::Initializer() { InitAsStandaloneIfNecessary(); }
 381
 382 ScopedReport::ScopedReport(ReportOptions Opts, Location SummaryLoc,
 383                            ErrorType Type)
 384     : Opts(Opts), SummaryLoc(SummaryLoc), Type(Type) {}
 385
 386 ScopedReport::~ScopedReport() {
 387   MaybePrintStackTrace(Opts.pc, Opts.bp);
 388   MaybeReportErrorSummary(SummaryLoc, Type);
 389
 390   if (common_flags()->print_module_map >= 2)
 391     DumpProcessMap();
 392
 393   if (flags()->halt_on_error)
 394     Die();
 395 }
 396
 397 ALIGNED(64) static char suppression_placeholder[sizeof(SuppressionContext)];
 398 static SuppressionContext *suppression_ctx = nullptr;
 399 static const char kVptrCheck[] = "vptr_check";
 400 static const char *kSuppressionTypes[] = {
 401 #define UBSAN_CHECK(Name, SummaryKind, FSanitizeFlagName) FSanitizeFlagName,
 402 #include "ubsan_checks.inc"
 403 #undef UBSAN_CHECK
 404     kVptrCheck,
 405 };
 406
 407 void __ubsan::InitializeSuppressions() {
 408   CHECK_EQ(nullptr, suppression_ctx);
 409   suppression_ctx = new (suppression_placeholder)
 410       SuppressionContext(kSuppressionTypes, ARRAY_SIZE(kSuppressionTypes));
 411   suppression_ctx->ParseFromFile(flags()->suppressions);
 412 }
 413
 414 bool __ubsan::IsVptrCheckSuppressed(const char *TypeName) {
 415   InitAsStandaloneIfNecessary();
 416   CHECK(suppression_ctx);
 417   Suppression *s;
 418   return suppression_ctx->Match(TypeName, kVptrCheck, &s);
 419 }
 420
 421 bool __ubsan::IsPCSuppressed(ErrorType ET, uptr PC, const char *Filename) {
 422   InitAsStandaloneIfNecessary();
 423   CHECK(suppression_ctx);
 424   const char *SuppType = ConvertTypeToFlagName(ET);
 425   // Fast path: don't symbolize PC if there is no suppressions for given UB
 426   // type.
 427   if (!suppression_ctx->HasSuppressionType(SuppType))
 428     return false;
 429   Suppression *s = nullptr;
 430   // Suppress by file name known to runtime.
 431   if (Filename != nullptr && suppression_ctx->Match(Filename, SuppType, &s))
 432     return true;
 433   // Suppress by module name.
 434   if (const char *Module = Symbolizer::GetOrInit()->GetModuleNameForPc(PC)) {
 435     if (suppression_ctx->Match(Module, SuppType, &s))
 436       return true;
 437   }
 438   // Suppress by function or source file name from debug info.
 439   SymbolizedStackHolder Stack(Symbolizer::GetOrInit()->SymbolizePC(PC));
 440   const AddressInfo &AI = Stack.get()->info;
 441   return suppression_ctx->Match(AI.function, SuppType, &s) ||
 442          suppression_ctx->Match(AI.file, SuppType, &s);
 443 }
 444
 445 #endif  // CAN_SANITIZE_UB