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-rw-r--r--lib/fuzzer/FuzzerTracePC.cpp343
1 files changed, 191 insertions, 152 deletions
diff --git a/lib/fuzzer/FuzzerTracePC.cpp b/lib/fuzzer/FuzzerTracePC.cpp
index 80b33105bb22..4a1308de5504 100644
--- a/lib/fuzzer/FuzzerTracePC.cpp
+++ b/lib/fuzzer/FuzzerTracePC.cpp
@@ -1,9 +1,8 @@
//===- FuzzerTracePC.cpp - PC tracing--------------------------------------===//
//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Trace PCs.
@@ -24,15 +23,6 @@
#include "FuzzerValueBitMap.h"
#include <set>
-// The coverage counters and PCs.
-// These are declared as global variables named "__sancov_*" to simplify
-// experiments with inlined instrumentation.
-alignas(64) ATTRIBUTE_INTERFACE
-uint8_t __sancov_trace_pc_guard_8bit_counters[fuzzer::TracePC::kNumPCs];
-
-ATTRIBUTE_INTERFACE
-uintptr_t __sancov_trace_pc_pcs[fuzzer::TracePC::kNumPCs];
-
// Used by -fsanitize-coverage=stack-depth to track stack depth
ATTRIBUTES_INTERFACE_TLS_INITIAL_EXEC uintptr_t __sancov_lowest_stack;
@@ -40,33 +30,80 @@ namespace fuzzer {
TracePC TPC;
-uint8_t *TracePC::Counters() const {
- return __sancov_trace_pc_guard_8bit_counters;
-}
-
-uintptr_t *TracePC::PCs() const {
- return __sancov_trace_pc_pcs;
-}
-
size_t TracePC::GetTotalPCCoverage() {
- if (ObservedPCs.size())
- return ObservedPCs.size();
- size_t Res = 0;
- for (size_t i = 1, N = GetNumPCs(); i < N; i++)
- if (PCs()[i])
- Res++;
- return Res;
+ return ObservedPCs.size();
}
void TracePC::HandleInline8bitCountersInit(uint8_t *Start, uint8_t *Stop) {
if (Start == Stop) return;
- if (NumModulesWithInline8bitCounters &&
- ModuleCounters[NumModulesWithInline8bitCounters-1].Start == Start) return;
- assert(NumModulesWithInline8bitCounters <
- sizeof(ModuleCounters) / sizeof(ModuleCounters[0]));
- ModuleCounters[NumModulesWithInline8bitCounters++] = {Start, Stop};
- NumInline8bitCounters += Stop - Start;
+ if (NumModules &&
+ Modules[NumModules - 1].Start() == Start)
+ return;
+ assert(NumModules <
+ sizeof(Modules) / sizeof(Modules[0]));
+ auto &M = Modules[NumModules++];
+ uint8_t *AlignedStart = RoundUpByPage(Start);
+ uint8_t *AlignedStop = RoundDownByPage(Stop);
+ size_t NumFullPages = AlignedStop > AlignedStart ?
+ (AlignedStop - AlignedStart) / PageSize() : 0;
+ bool NeedFirst = Start < AlignedStart || !NumFullPages;
+ bool NeedLast = Stop > AlignedStop && AlignedStop >= AlignedStart;
+ M.NumRegions = NumFullPages + NeedFirst + NeedLast;;
+ assert(M.NumRegions > 0);
+ M.Regions = new Module::Region[M.NumRegions];
+ assert(M.Regions);
+ size_t R = 0;
+ if (NeedFirst)
+ M.Regions[R++] = {Start, std::min(Stop, AlignedStart), true, false};
+ for (uint8_t *P = AlignedStart; P < AlignedStop; P += PageSize())
+ M.Regions[R++] = {P, P + PageSize(), true, true};
+ if (NeedLast)
+ M.Regions[R++] = {AlignedStop, Stop, true, false};
+ assert(R == M.NumRegions);
+ assert(M.Size() == (size_t)(Stop - Start));
+ assert(M.Stop() == Stop);
+ assert(M.Start() == Start);
+ NumInline8bitCounters += M.Size();
+}
+
+// Mark all full page counter regions as PROT_NONE and set Enabled=false.
+// The first time the instrumented code hits such a protected/disabled
+// counter region we should catch a SEGV and call UnprotectLazyCounters,
+// which will mark the page as PROT_READ|PROT_WRITE and set Enabled=true.
+//
+// Whenever other functions iterate over the counters they should ignore
+// regions with Enabled=false.
+void TracePC::ProtectLazyCounters() {
+ size_t NumPagesProtected = 0;
+ IterateCounterRegions([&](Module::Region &R) {
+ if (!R.OneFullPage) return;
+ if (Mprotect(R.Start, R.Stop - R.Start, false)) {
+ R.Enabled = false;
+ NumPagesProtected++;
+ }
+ });
+ if (NumPagesProtected)
+ Printf("INFO: %zd pages of counters where protected;"
+ " libFuzzer's SEGV handler must be installed\n",
+ NumPagesProtected);
+}
+
+bool TracePC::UnprotectLazyCounters(void *CounterPtr) {
+ // Printf("UnprotectLazyCounters: %p\n", CounterPtr);
+ if (!CounterPtr)
+ return false;
+ bool Done = false;
+ uint8_t *Addr = reinterpret_cast<uint8_t *>(CounterPtr);
+ IterateCounterRegions([&](Module::Region &R) {
+ if (!R.OneFullPage || R.Enabled || Done) return;
+ if (Addr >= R.Start && Addr < R.Stop)
+ if (Mprotect(R.Start, R.Stop - R.Start, true)) {
+ R.Enabled = true;
+ Done = true;
+ }
+ });
+ return Done;
}
void TracePC::HandlePCsInit(const uintptr_t *Start, const uintptr_t *Stop) {
@@ -78,38 +115,13 @@ void TracePC::HandlePCsInit(const uintptr_t *Start, const uintptr_t *Stop) {
NumPCsInPCTables += E - B;
}
-void TracePC::HandleInit(uint32_t *Start, uint32_t *Stop) {
- if (Start == Stop || *Start) return;
- assert(NumModules < sizeof(Modules) / sizeof(Modules[0]));
- for (uint32_t *P = Start; P < Stop; P++) {
- NumGuards++;
- if (NumGuards == kNumPCs) {
- RawPrint(
- "WARNING: The binary has too many instrumented PCs.\n"
- " You may want to reduce the size of the binary\n"
- " for more efficient fuzzing and precise coverage data\n");
- }
- *P = NumGuards % kNumPCs;
- }
- Modules[NumModules].Start = Start;
- Modules[NumModules].Stop = Stop;
- NumModules++;
-}
-
void TracePC::PrintModuleInfo() {
- if (NumGuards) {
- Printf("INFO: Loaded %zd modules (%zd guards): ", NumModules, NumGuards);
- for (size_t i = 0; i < NumModules; i++)
- Printf("%zd [%p, %p), ", Modules[i].Stop - Modules[i].Start,
- Modules[i].Start, Modules[i].Stop);
- Printf("\n");
- }
- if (NumModulesWithInline8bitCounters) {
+ if (NumModules) {
Printf("INFO: Loaded %zd modules (%zd inline 8-bit counters): ",
- NumModulesWithInline8bitCounters, NumInline8bitCounters);
- for (size_t i = 0; i < NumModulesWithInline8bitCounters; i++)
- Printf("%zd [%p, %p), ", ModuleCounters[i].Stop - ModuleCounters[i].Start,
- ModuleCounters[i].Start, ModuleCounters[i].Stop);
+ NumModules, NumInline8bitCounters);
+ for (size_t i = 0; i < NumModules; i++)
+ Printf("%zd [%p, %p), ", Modules[i].Size(), Modules[i].Start(),
+ Modules[i].Stop());
Printf("\n");
}
if (NumPCTables) {
@@ -121,8 +133,7 @@ void TracePC::PrintModuleInfo() {
}
Printf("\n");
- if ((NumGuards && NumGuards != NumPCsInPCTables) ||
- (NumInline8bitCounters && NumInline8bitCounters != NumPCsInPCTables)) {
+ if (NumInline8bitCounters && NumInline8bitCounters != NumPCsInPCTables) {
Printf("ERROR: The size of coverage PC tables does not match the\n"
"number of instrumented PCs. This might be a compiler bug,\n"
"please contact the libFuzzer developers.\n"
@@ -163,7 +174,7 @@ inline ALWAYS_INLINE uintptr_t GetPreviousInstructionPc(uintptr_t PC) {
/// \return the address of the next instruction.
/// Note: the logic is copied from `sanitizer_common/sanitizer_stacktrace.cc`
-inline ALWAYS_INLINE uintptr_t GetNextInstructionPc(uintptr_t PC) {
+ALWAYS_INLINE uintptr_t TracePC::GetNextInstructionPc(uintptr_t PC) {
#if defined(__mips__)
return PC + 8;
#elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) || \
@@ -176,41 +187,34 @@ inline ALWAYS_INLINE uintptr_t GetNextInstructionPc(uintptr_t PC) {
void TracePC::UpdateObservedPCs() {
Vector<uintptr_t> CoveredFuncs;
- auto ObservePC = [&](uintptr_t PC) {
- if (ObservedPCs.insert(PC).second && DoPrintNewPCs) {
- PrintPC("\tNEW_PC: %p %F %L", "\tNEW_PC: %p", GetNextInstructionPc(PC));
+ auto ObservePC = [&](const PCTableEntry *TE) {
+ if (ObservedPCs.insert(TE).second && DoPrintNewPCs) {
+ PrintPC("\tNEW_PC: %p %F %L", "\tNEW_PC: %p",
+ GetNextInstructionPc(TE->PC));
Printf("\n");
}
};
- auto Observe = [&](const PCTableEntry &TE) {
- if (TE.PCFlags & 1)
- if (++ObservedFuncs[TE.PC] == 1 && NumPrintNewFuncs)
- CoveredFuncs.push_back(TE.PC);
- ObservePC(TE.PC);
+ auto Observe = [&](const PCTableEntry *TE) {
+ if (PcIsFuncEntry(TE))
+ if (++ObservedFuncs[TE->PC] == 1 && NumPrintNewFuncs)
+ CoveredFuncs.push_back(TE->PC);
+ ObservePC(TE);
};
if (NumPCsInPCTables) {
if (NumInline8bitCounters == NumPCsInPCTables) {
- for (size_t i = 0; i < NumModulesWithInline8bitCounters; i++) {
- uint8_t *Beg = ModuleCounters[i].Start;
- size_t Size = ModuleCounters[i].Stop - Beg;
- assert(Size ==
- (size_t)(ModulePCTable[i].Stop - ModulePCTable[i].Start));
- for (size_t j = 0; j < Size; j++)
- if (Beg[j])
- Observe(ModulePCTable[i].Start[j]);
- }
- } else if (NumGuards == NumPCsInPCTables) {
- size_t GuardIdx = 1;
for (size_t i = 0; i < NumModules; i++) {
- uint32_t *Beg = Modules[i].Start;
- size_t Size = Modules[i].Stop - Beg;
- assert(Size ==
+ auto &M = Modules[i];
+ assert(M.Size() ==
(size_t)(ModulePCTable[i].Stop - ModulePCTable[i].Start));
- for (size_t j = 0; j < Size; j++, GuardIdx++)
- if (Counters()[GuardIdx])
- Observe(ModulePCTable[i].Start[j]);
+ for (size_t r = 0; r < M.NumRegions; r++) {
+ auto &R = M.Regions[r];
+ if (!R.Enabled) continue;
+ for (uint8_t *P = R.Start; P < R.Stop; P++)
+ if (*P)
+ Observe(&ModulePCTable[i].Start[M.Idx(P)]);
+ }
}
}
}
@@ -223,6 +227,27 @@ void TracePC::UpdateObservedPCs() {
}
}
+uintptr_t TracePC::PCTableEntryIdx(const PCTableEntry *TE) {
+ size_t TotalTEs = 0;
+ for (size_t i = 0; i < NumPCTables; i++) {
+ auto &M = ModulePCTable[i];
+ if (TE >= M.Start && TE < M.Stop)
+ return TotalTEs + TE - M.Start;
+ TotalTEs += M.Stop - M.Start;
+ }
+ assert(0);
+ return 0;
+}
+
+const TracePC::PCTableEntry *TracePC::PCTableEntryByIdx(uintptr_t Idx) {
+ for (size_t i = 0; i < NumPCTables; i++) {
+ auto &M = ModulePCTable[i];
+ size_t Size = M.Stop - M.Start;
+ if (Idx < Size) return &M.Start[Idx];
+ Idx -= Size;
+ }
+ return nullptr;
+}
static std::string GetModuleName(uintptr_t PC) {
char ModulePathRaw[4096] = ""; // What's PATH_MAX in portable C++?
@@ -242,47 +267,38 @@ void TracePC::IterateCoveredFunctions(CallBack CB) {
auto ModuleName = GetModuleName(M.Start->PC);
for (auto NextFE = M.Start; NextFE < M.Stop; ) {
auto FE = NextFE;
- assert((FE->PCFlags & 1) && "Not a function entry point");
+ assert(PcIsFuncEntry(FE) && "Not a function entry point");
do {
NextFE++;
- } while (NextFE < M.Stop && !(NextFE->PCFlags & 1));
- if (ObservedFuncs.count(FE->PC))
- CB(FE, NextFE, ObservedFuncs[FE->PC]);
+ } while (NextFE < M.Stop && !(PcIsFuncEntry(NextFE)));
+ CB(FE, NextFE, ObservedFuncs[FE->PC]);
}
}
}
void TracePC::SetFocusFunction(const std::string &FuncName) {
// This function should be called once.
- assert(FocusFunction.first > NumModulesWithInline8bitCounters);
+ assert(!FocusFunctionCounterPtr);
if (FuncName.empty())
return;
- for (size_t M = 0; M < NumModulesWithInline8bitCounters; M++) {
+ for (size_t M = 0; M < NumModules; M++) {
auto &PCTE = ModulePCTable[M];
size_t N = PCTE.Stop - PCTE.Start;
for (size_t I = 0; I < N; I++) {
- if (!(PCTE.Start[I].PCFlags & 1)) continue; // not a function entry.
+ if (!(PcIsFuncEntry(&PCTE.Start[I]))) continue; // not a function entry.
auto Name = DescribePC("%F", GetNextInstructionPc(PCTE.Start[I].PC));
if (Name[0] == 'i' && Name[1] == 'n' && Name[2] == ' ')
Name = Name.substr(3, std::string::npos);
if (FuncName != Name) continue;
Printf("INFO: Focus function is set to '%s'\n", Name.c_str());
- FocusFunction = {M, I};
+ FocusFunctionCounterPtr = Modules[M].Start() + I;
return;
}
}
}
bool TracePC::ObservedFocusFunction() {
- size_t I = FocusFunction.first;
- size_t J = FocusFunction.second;
- if (I >= NumModulesWithInline8bitCounters)
- return false;
- auto &MC = ModuleCounters[I];
- size_t Size = MC.Stop - MC.Start;
- if (J >= Size)
- return false;
- return MC.Start[J] != 0;
+ return FocusFunctionCounterPtr && *FocusFunctionCounterPtr;
}
void TracePC::PrintCoverage() {
@@ -306,32 +322,24 @@ void TracePC::PrintCoverage() {
if (FunctionStr.find("in ") == 0)
FunctionStr = FunctionStr.substr(3);
std::string LineStr = DescribePC("%l", VisualizePC);
- size_t Line = std::stoul(LineStr);
size_t NumEdges = Last - First;
Vector<uintptr_t> UncoveredPCs;
for (auto TE = First; TE < Last; TE++)
- if (!ObservedPCs.count(TE->PC))
+ if (!ObservedPCs.count(TE))
UncoveredPCs.push_back(TE->PC);
- Printf("COVERED_FUNC: hits: %zd", Counter);
+ Printf("%sCOVERED_FUNC: hits: %zd", Counter ? "" : "UN", Counter);
Printf(" edges: %zd/%zd", NumEdges - UncoveredPCs.size(), NumEdges);
- Printf(" %s %s:%zd\n", FunctionStr.c_str(), FileStr.c_str(), Line);
- for (auto PC: UncoveredPCs)
- Printf(" UNCOVERED_PC: %s\n",
- DescribePC("%s:%l", GetNextInstructionPc(PC)).c_str());
+ Printf(" %s %s:%s\n", FunctionStr.c_str(), FileStr.c_str(),
+ LineStr.c_str());
+ if (Counter)
+ for (auto PC : UncoveredPCs)
+ Printf(" UNCOVERED_PC: %s\n",
+ DescribePC("%s:%l", GetNextInstructionPc(PC)).c_str());
};
IterateCoveredFunctions(CoveredFunctionCallback);
}
-void TracePC::DumpCoverage() {
- if (EF->__sanitizer_dump_coverage) {
- Vector<uintptr_t> PCsCopy(GetNumPCs());
- for (size_t i = 0; i < GetNumPCs(); i++)
- PCsCopy[i] = PCs()[i] ? GetPreviousInstructionPc(PCs()[i]) : 0;
- EF->__sanitizer_dump_coverage(PCsCopy.data(), PCsCopy.size());
- }
-}
-
// Value profile.
// We keep track of various values that affect control flow.
// These values are inserted into a bit-set-based hash map.
@@ -361,11 +369,16 @@ void TracePC::AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
Hash ^= (T << 8) | B2[i];
}
size_t I = 0;
- for (; I < Len; I++)
- if (B1[I] != B2[I] || (StopAtZero && B1[I] == 0))
+ uint8_t HammingDistance = 0;
+ for (; I < Len; I++) {
+ if (B1[I] != B2[I] || (StopAtZero && B1[I] == 0)) {
+ HammingDistance = Popcountll(B1[I] ^ B2[I]);
break;
+ }
+ }
size_t PC = reinterpret_cast<size_t>(caller_pc);
size_t Idx = (PC & 4095) | (I << 12);
+ Idx += HammingDistance;
ValueProfileMap.AddValue(Idx);
TORCW.Insert(Idx ^ Hash, Word(B1, Len), Word(B2, Len));
}
@@ -400,11 +413,10 @@ static size_t InternalStrnlen2(const char *S1, const char *S2) {
}
void TracePC::ClearInlineCounters() {
- for (size_t i = 0; i < NumModulesWithInline8bitCounters; i++) {
- uint8_t *Beg = ModuleCounters[i].Start;
- size_t Size = ModuleCounters[i].Stop - Beg;
- memset(Beg, 0, Size);
- }
+ IterateCounterRegions([](const Module::Region &R){
+ if (R.Enabled)
+ memset(R.Start, 0, R.Stop - R.Start);
+ });
}
ATTRIBUTE_NO_SANITIZE_ALL
@@ -417,16 +429,25 @@ uintptr_t TracePC::GetMaxStackOffset() const {
return InitialStack - __sancov_lowest_stack; // Stack grows down
}
+void WarnAboutDeprecatedInstrumentation(const char *flag) {
+ // Use RawPrint because Printf cannot be used on Windows before OutputFile is
+ // initialized.
+ RawPrint(flag);
+ RawPrint(
+ " is no longer supported by libFuzzer.\n"
+ "Please either migrate to a compiler that supports -fsanitize=fuzzer\n"
+ "or use an older version of libFuzzer\n");
+ exit(1);
+}
+
} // namespace fuzzer
extern "C" {
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
void __sanitizer_cov_trace_pc_guard(uint32_t *Guard) {
- uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
- uint32_t Idx = *Guard;
- __sancov_trace_pc_pcs[Idx] = PC;
- __sancov_trace_pc_guard_8bit_counters[Idx]++;
+ fuzzer::WarnAboutDeprecatedInstrumentation(
+ "-fsanitize-coverage=trace-pc-guard");
}
// Best-effort support for -fsanitize-coverage=trace-pc, which is available
@@ -434,15 +455,13 @@ void __sanitizer_cov_trace_pc_guard(uint32_t *Guard) {
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
void __sanitizer_cov_trace_pc() {
- uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
- uintptr_t Idx = PC & (((uintptr_t)1 << fuzzer::TracePC::kTracePcBits) - 1);
- __sancov_trace_pc_pcs[Idx] = PC;
- __sancov_trace_pc_guard_8bit_counters[Idx]++;
+ fuzzer::WarnAboutDeprecatedInstrumentation("-fsanitize-coverage=trace-pc");
}
ATTRIBUTE_INTERFACE
void __sanitizer_cov_trace_pc_guard_init(uint32_t *Start, uint32_t *Stop) {
- fuzzer::TPC.HandleInit(Start, Stop);
+ fuzzer::WarnAboutDeprecatedInstrumentation(
+ "-fsanitize-coverage=trace-pc-guard");
}
ATTRIBUTE_INTERFACE
@@ -537,24 +556,44 @@ void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases) {
uint64_t N = Cases[0];
uint64_t ValSizeInBits = Cases[1];
uint64_t *Vals = Cases + 2;
- // Skip the most common and the most boring case.
- if (Vals[N - 1] < 256 && Val < 256)
+ // Skip the most common and the most boring case: all switch values are small.
+ // We may want to skip this at compile-time, but it will make the
+ // instrumentation less general.
+ if (Vals[N - 1] < 256)
+ return;
+ // Also skip small inputs values, they won't give good signal.
+ if (Val < 256)
return;
uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
size_t i;
- uint64_t Token = 0;
+ uint64_t Smaller = 0;
+ uint64_t Larger = ~(uint64_t)0;
+ // Find two switch values such that Smaller < Val < Larger.
+ // Use 0 and 0xfff..f as the defaults.
for (i = 0; i < N; i++) {
- Token = Val ^ Vals[i];
- if (Val < Vals[i])
+ if (Val < Vals[i]) {
+ Larger = Vals[i];
break;
+ }
+ if (Val > Vals[i]) Smaller = Vals[i];
}
- if (ValSizeInBits == 16)
- fuzzer::TPC.HandleCmp(PC + i, static_cast<uint16_t>(Token), (uint16_t)(0));
- else if (ValSizeInBits == 32)
- fuzzer::TPC.HandleCmp(PC + i, static_cast<uint32_t>(Token), (uint32_t)(0));
- else
- fuzzer::TPC.HandleCmp(PC + i, Token, (uint64_t)(0));
+ // Apply HandleCmp to {Val,Smaller} and {Val, Larger},
+ // use i as the PC modifier for HandleCmp.
+ if (ValSizeInBits == 16) {
+ fuzzer::TPC.HandleCmp(PC + 2 * i, static_cast<uint16_t>(Val),
+ (uint16_t)(Smaller));
+ fuzzer::TPC.HandleCmp(PC + 2 * i + 1, static_cast<uint16_t>(Val),
+ (uint16_t)(Larger));
+ } else if (ValSizeInBits == 32) {
+ fuzzer::TPC.HandleCmp(PC + 2 * i, static_cast<uint32_t>(Val),
+ (uint32_t)(Smaller));
+ fuzzer::TPC.HandleCmp(PC + 2 * i + 1, static_cast<uint32_t>(Val),
+ (uint32_t)(Larger));
+ } else {
+ fuzzer::TPC.HandleCmp(PC + 2*i, Val, Smaller);
+ fuzzer::TPC.HandleCmp(PC + 2*i + 1, Val, Larger);
+ }
}
ATTRIBUTE_INTERFACE
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-20 01:08:46 +0000