vendor/llvm/llvm-trunk-r238337

1 files changed, 365 insertions, 0 deletions

diff --git a/lib/Fuzzer/FuzzerTraceState.cpp b/lib/Fuzzer/FuzzerTraceState.cpp
new file mode 100644
index 000000000000..ddb0764930fe
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+++ b/lib/Fuzzer/FuzzerTraceState.cpp
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+//===- FuzzerTraceState.cpp - Trace-based fuzzer mutator ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This file implements a mutation algorithm based on instruction traces and
+// on taint analysis feedback from DFSan.
+//
+// Instruction traces are special hooks inserted by the compiler around
+// interesting instructions. Currently supported traces:
+//   * __sanitizer_cov_trace_cmp -- inserted before every ICMP instruction,
+//    receives the type, size and arguments of ICMP.
+//
+// Every time a traced event is intercepted we analyse the data involved
+// in the event and suggest a mutation for future executions.
+// For example if 4 bytes of data that derive from input bytes {4,5,6,7}
+// are compared with a constant 12345,
+// we try to insert 12345, 12344, 12346 into bytes
+// {4,5,6,7} of the next fuzzed inputs.
+//
+// The fuzzer can work only with the traces, or with both traces and DFSan.
+//
+// DataFlowSanitizer (DFSan) is a tool for
+// generalised dynamic data flow (taint) analysis:
+// http://clang.llvm.org/docs/DataFlowSanitizer.html .
+//
+// The approach with DFSan-based fuzzing has some similarity to
+// "Taint-based Directed Whitebox Fuzzing"
+// by Vijay Ganesh & Tim Leek & Martin Rinard:
+// http://dspace.mit.edu/openaccess-disseminate/1721.1/59320,
+// but it uses a full blown LLVM IR taint analysis and separate instrumentation
+// to analyze all of the "attack points" at once.
+//
+// Workflow with DFSan:
+//   * lib/Fuzzer/Fuzzer*.cpp is compiled w/o any instrumentation.
+//   * The code under test is compiled with DFSan *and* with instruction traces.
+//   * Every call to HOOK(a,b) is replaced by DFSan with
+//     __dfsw_HOOK(a, b, label(a), label(b)) so that __dfsw_HOOK
+//     gets all the taint labels for the arguments.
+//   * At the Fuzzer startup we assign a unique DFSan label
+//     to every byte of the input string (Fuzzer::CurrentUnit) so that for any
+//     chunk of data we know which input bytes it has derived from.
+//   * The __dfsw_* functions (implemented in this file) record the
+//     parameters (i.e. the application data and the corresponding taint labels)
+//     in a global state.
+//   * Fuzzer::ApplyTraceBasedMutation() tries to use the data recorded
+//     by __dfsw_* hooks to guide the fuzzing towards new application states.
+//
+// Parts of this code will not function when DFSan is not linked in.
+// Instead of using ifdefs and thus requiring a separate build of lib/Fuzzer
+// we redeclare the dfsan_* interface functions as weak and check if they
+// are nullptr before calling.
+// If this approach proves to be useful we may add attribute(weak) to the
+// dfsan declarations in dfsan_interface.h
+//
+// This module is in the "proof of concept" stage.
+// It is capable of solving only the simplest puzzles
+// like test/dfsan/DFSanSimpleCmpTest.cpp.
+//===----------------------------------------------------------------------===//
+
+/* Example of manual usage (-fsanitize=dataflow is optional):
+(
+  cd $LLVM/lib/Fuzzer/
+  clang  -fPIC -c -g -O2 -std=c++11 Fuzzer*.cpp
+  clang++ -O0 -std=c++11 -fsanitize-coverage=edge,trace-cmp \
+    -fsanitize=dataflow \
+    test/dfsan/DFSanSimpleCmpTest.cpp Fuzzer*.o
+  ./a.out
+)
+*/
+
+#include "FuzzerInternal.h"
+#include <sanitizer/dfsan_interface.h>
+
+#include <algorithm>
+#include <cstring>
+#include <unordered_map>
+
+extern "C" {
+__attribute__((weak))
+dfsan_label dfsan_create_label(const char *desc, void *userdata);
+__attribute__((weak))
+void dfsan_set_label(dfsan_label label, void *addr, size_t size);
+__attribute__((weak))
+void dfsan_add_label(dfsan_label label, void *addr, size_t size);
+__attribute__((weak))
+const struct dfsan_label_info *dfsan_get_label_info(dfsan_label label);
+__attribute__((weak))
+dfsan_label dfsan_read_label(const void *addr, size_t size);
+}  // extern "C"
+
+namespace fuzzer {
+
+static bool ReallyHaveDFSan() {
+  return &dfsan_create_label != nullptr;
+}
+
+// These values are copied from include/llvm/IR/InstrTypes.h.
+// We do not include the LLVM headers here to remain independent.
+// If these values ever change, an assertion in ComputeCmp will fail.
+enum Predicate {
+  ICMP_EQ = 32,  ///< equal
+  ICMP_NE = 33,  ///< not equal
+  ICMP_UGT = 34, ///< unsigned greater than
+  ICMP_UGE = 35, ///< unsigned greater or equal
+  ICMP_ULT = 36, ///< unsigned less than
+  ICMP_ULE = 37, ///< unsigned less or equal
+  ICMP_SGT = 38, ///< signed greater than
+  ICMP_SGE = 39, ///< signed greater or equal
+  ICMP_SLT = 40, ///< signed less than
+  ICMP_SLE = 41, ///< signed less or equal
+};
+
+template <class U, class S>
+bool ComputeCmp(size_t CmpType, U Arg1, U Arg2) {
+  switch(CmpType) {
+    case ICMP_EQ : return Arg1 == Arg2;
+    case ICMP_NE : return Arg1 != Arg2;
+    case ICMP_UGT: return Arg1 > Arg2;
+    case ICMP_UGE: return Arg1 >= Arg2;
+    case ICMP_ULT: return Arg1 < Arg2;
+    case ICMP_ULE: return Arg1 <= Arg2;
+    case ICMP_SGT: return (S)Arg1 > (S)Arg2;
+    case ICMP_SGE: return (S)Arg1 >= (S)Arg2;
+    case ICMP_SLT: return (S)Arg1 < (S)Arg2;
+    case ICMP_SLE: return (S)Arg1 <= (S)Arg2;
+    default: assert(0 && "unsupported CmpType");
+  }
+  return false;
+}
+
+static bool ComputeCmp(size_t CmpSize, size_t CmpType, uint64_t Arg1,
+                       uint64_t Arg2) {
+  if (CmpSize == 8) return ComputeCmp<uint64_t, int64_t>(CmpType, Arg1, Arg2);
+  if (CmpSize == 4) return ComputeCmp<uint32_t, int32_t>(CmpType, Arg1, Arg2);
+  if (CmpSize == 2) return ComputeCmp<uint16_t, int16_t>(CmpType, Arg1, Arg2);
+  if (CmpSize == 1) return ComputeCmp<uint8_t, int8_t>(CmpType, Arg1, Arg2);
+  assert(0 && "unsupported type size");
+  return true;
+}
+
+// As a simplification we use the range of input bytes instead of a set of input
+// bytes.
+struct LabelRange {
+  uint16_t Beg, End;  // Range is [Beg, End), thus Beg==End is an empty range.
+
+  LabelRange(uint16_t Beg = 0, uint16_t End = 0) : Beg(Beg), End(End) {}
+
+  static LabelRange Join(LabelRange LR1, LabelRange LR2) {
+    if (LR1.Beg == LR1.End) return LR2;
+    if (LR2.Beg == LR2.End) return LR1;
+    return {std::min(LR1.Beg, LR2.Beg), std::max(LR1.End, LR2.End)};
+  }
+  LabelRange &Join(LabelRange LR) {
+    return *this = Join(*this, LR);
+  }
+  static LabelRange Singleton(const dfsan_label_info *LI) {
+    uint16_t Idx = (uint16_t)(uintptr_t)LI->userdata;
+    assert(Idx > 0);
+    return {(uint16_t)(Idx - 1), Idx};
+  }
+};
+
+// For now, very simple: put Size bytes of Data at position Pos.
+struct TraceBasedMutation {
+  size_t Pos;
+  size_t Size;
+  uint64_t Data;
+};
+
+class TraceState {
+ public:
+   TraceState(const Fuzzer::FuzzingOptions &Options, const Unit &CurrentUnit)
+       : Options(Options), CurrentUnit(CurrentUnit) {}
+
+  LabelRange GetLabelRange(dfsan_label L);
+  void DFSanCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
+                        uint64_t Arg1, uint64_t Arg2, dfsan_label L1,
+                        dfsan_label L2);
+  void TraceCmpCallback(size_t CmpSize, size_t CmpType, uint64_t Arg1,
+                        uint64_t Arg2);
+  int TryToAddDesiredData(uint64_t PresentData, uint64_t DesiredData,
+                           size_t DataSize);
+
+  void StartTraceRecording() {
+    if (!Options.UseTraces) return;
+    RecordingTraces = true;
+    Mutations.clear();
+  }
+
+  size_t StopTraceRecording() {
+    RecordingTraces = false;
+    std::random_shuffle(Mutations.begin(), Mutations.end());
+    return Mutations.size();
+  }
+
+  void ApplyTraceBasedMutation(size_t Idx, fuzzer::Unit *U);
+
+ private:
+  bool IsTwoByteData(uint64_t Data) {
+    int64_t Signed = static_cast<int64_t>(Data);
+    Signed >>= 16;
+    return Signed == 0 || Signed == -1L;
+  }
+  bool RecordingTraces = false;
+  std::vector<TraceBasedMutation> Mutations;
+  LabelRange LabelRanges[1 << (sizeof(dfsan_label) * 8)] = {};
+  const Fuzzer::FuzzingOptions &Options;
+  const Unit &CurrentUnit;
+};
+
+LabelRange TraceState::GetLabelRange(dfsan_label L) {
+  LabelRange &LR = LabelRanges[L];
+  if (LR.Beg < LR.End || L == 0)
+    return LR;
+  const dfsan_label_info *LI = dfsan_get_label_info(L);
+  if (LI->l1 || LI->l2)
+    return LR = LabelRange::Join(GetLabelRange(LI->l1), GetLabelRange(LI->l2));
+  return LR = LabelRange::Singleton(LI);
+}
+
+void TraceState::ApplyTraceBasedMutation(size_t Idx, fuzzer::Unit *U) {
+  assert(Idx < Mutations.size());
+  auto &M = Mutations[Idx];
+  if (Options.Verbosity >= 3)
+    Printf("TBM %zd %zd %zd\n", M.Pos, M.Size, M.Data);
+  if (M.Pos + M.Size > U->size()) return;
+  memcpy(U->data() + M.Pos, &M.Data, M.Size);
+}
+
+void TraceState::DFSanCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
+                                  uint64_t Arg1, uint64_t Arg2, dfsan_label L1,
+                                  dfsan_label L2) {
+  assert(ReallyHaveDFSan());
+  if (!RecordingTraces) return;
+  if (L1 == 0 && L2 == 0)
+    return;  // Not actionable.
+  if (L1 != 0 && L2 != 0)
+    return;  // Probably still actionable.
+  bool Res = ComputeCmp(CmpSize, CmpType, Arg1, Arg2);
+  uint64_t Data = L1 ? Arg2 : Arg1;
+  LabelRange LR = L1 ? GetLabelRange(L1) : GetLabelRange(L2);
+
+  for (size_t Pos = LR.Beg; Pos + CmpSize <= LR.End; Pos++) {
+    Mutations.push_back({Pos, CmpSize, Data});
+    Mutations.push_back({Pos, CmpSize, Data + 1});
+    Mutations.push_back({Pos, CmpSize, Data - 1});
+  }
+
+  if (CmpSize > LR.End - LR.Beg)
+    Mutations.push_back({LR.Beg, (unsigned)(LR.End - LR.Beg), Data});
+
+
+  if (Options.Verbosity >= 3)
+    Printf("DFSAN: PC %lx S %zd T %zd A1 %llx A2 %llx R %d L1 %d L2 %d MU %zd\n",
+           PC, CmpSize, CmpType, Arg1, Arg2, Res, L1, L2, Mutations.size());
+}
+
+int TraceState::TryToAddDesiredData(uint64_t PresentData, uint64_t DesiredData,
+                                    size_t DataSize) {
+  int Res = 0;
+  const uint8_t *Beg = CurrentUnit.data();
+  const uint8_t *End = Beg + CurrentUnit.size();
+  for (const uint8_t *Cur = Beg; Cur < End; Cur += DataSize) {
+    Cur = (uint8_t *)memmem(Cur, End - Cur, &PresentData, DataSize);
+    if (!Cur)
+      break;
+    size_t Pos = Cur - Beg;
+    assert(Pos < CurrentUnit.size());
+    Mutations.push_back({Pos, DataSize, DesiredData});
+    Mutations.push_back({Pos, DataSize, DesiredData + 1});
+    Mutations.push_back({Pos, DataSize, DesiredData - 1});
+    Cur += DataSize;
+    Res++;
+  }
+  return Res;
+}
+
+void TraceState::TraceCmpCallback(size_t CmpSize, size_t CmpType, uint64_t Arg1,
+                        uint64_t Arg2) {
+  if (!RecordingTraces) return;
+  int Added = 0;
+  if (Options.Verbosity >= 3)
+    Printf("TraceCmp: %zd %zd\n", Arg1, Arg2);
+  Added += TryToAddDesiredData(Arg1, Arg2, CmpSize);
+  Added += TryToAddDesiredData(Arg2, Arg1, CmpSize);
+  if (!Added && CmpSize == 4 && IsTwoByteData(Arg1) && IsTwoByteData(Arg2)) {
+    Added += TryToAddDesiredData(Arg1, Arg2, 2);
+    Added += TryToAddDesiredData(Arg2, Arg1, 2);
+  }
+}
+
+static TraceState *TS;
+
+void Fuzzer::StartTraceRecording() {
+  if (!TS) return;
+  TS->StartTraceRecording();
+}
+
+size_t Fuzzer::StopTraceRecording() {
+  if (!TS) return 0;
+  return TS->StopTraceRecording();
+}
+
+void Fuzzer::ApplyTraceBasedMutation(size_t Idx, Unit *U) {
+  assert(TS);
+  TS->ApplyTraceBasedMutation(Idx, U);
+}
+
+void Fuzzer::InitializeTraceState() {
+  if (!Options.UseTraces) return;
+  TS = new TraceState(Options, CurrentUnit);
+  CurrentUnit.resize(Options.MaxLen);
+  // The rest really requires DFSan.
+  if (!ReallyHaveDFSan()) return;
+  for (size_t i = 0; i < static_cast<size_t>(Options.MaxLen); i++) {
+    dfsan_label L = dfsan_create_label("input", (void*)(i + 1));
+    // We assume that no one else has called dfsan_create_label before.
+    assert(L == i + 1);
+    dfsan_set_label(L, &CurrentUnit[i], 1);
+  }
+}
+
+}  // namespace fuzzer
+
+using fuzzer::TS;
+
+extern "C" {
+void __dfsw___sanitizer_cov_trace_cmp(uint64_t SizeAndType, uint64_t Arg1,
+                                      uint64_t Arg2, dfsan_label L0,
+                                      dfsan_label L1, dfsan_label L2) {
+  assert(TS);
+  assert(L0 == 0);
+  uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
+  uint64_t CmpSize = (SizeAndType >> 32) / 8;
+  uint64_t Type = (SizeAndType << 32) >> 32;
+  TS->DFSanCmpCallback(PC, CmpSize, Type, Arg1, Arg2, L1, L2);
+}
+
+void dfsan_weak_hook_memcmp(void *caller_pc, const void *s1, const void *s2,
+                            size_t n, dfsan_label s1_label,
+                            dfsan_label s2_label, dfsan_label n_label) {
+  assert(TS);
+  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
+  uint64_t S1 = 0, S2 = 0;
+  // Simplification: handle only first 8 bytes.
+  memcpy(&S1, s1, std::min(n, sizeof(S1)));
+  memcpy(&S2, s2, std::min(n, sizeof(S2)));
+  dfsan_label L1 = dfsan_read_label(s1, n);
+  dfsan_label L2 = dfsan_read_label(s2, n);
+  TS->DFSanCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2, L1, L2);
+}
+
+void __sanitizer_cov_trace_cmp(uint64_t SizeAndType, uint64_t Arg1,
+                               uint64_t Arg2) {
+  if (!TS) return;
+  uint64_t CmpSize = (SizeAndType >> 32) / 8;
+  uint64_t Type = (SizeAndType << 32) >> 32;
+  TS->TraceCmpCallback(CmpSize, Type, Arg1, Arg2);
+}
+
+}  // extern "C"