bye bye SanCov for CmpLog

5 files changed, 469 insertions, 45 deletions

diff --git a/llvm_mode/Makefile b/llvm_mode/Makefile
index 5567f793..db0af84c 100644
--- a/llvm_mode/Makefile
+++ b/llvm_mode/Makefile
@@ -132,9 +132,9 @@ ifeq "$(TEST_MMAP)" "1"
 endif
 
 ifndef AFL_TRACE_PC
-  PROGS      = ../afl-clang-fast ../afl-llvm-pass.so ../libLLVMInsTrim.so ../afl-llvm-rt.o ../afl-llvm-rt-32.o ../afl-llvm-rt-64.o ../compare-transform-pass.so ../split-compares-pass.so ../split-switches-pass.so ../cmplog-routines-pass.so
+  PROGS      = ../afl-clang-fast ../afl-llvm-pass.so ../libLLVMInsTrim.so ../afl-llvm-rt.o ../afl-llvm-rt-32.o ../afl-llvm-rt-64.o ../compare-transform-pass.so ../split-compares-pass.so ../split-switches-pass.so ../cmplog-routines-pass.so ../cmplog-instructions-pass.so
 else
-  PROGS      = ../afl-clang-fast ../afl-llvm-rt.o ../afl-llvm-rt-32.o ../afl-llvm-rt-64.o ../compare-transform-pass.so ../split-compares-pass.so ../split-switches-pass.so
+  PROGS      = ../afl-clang-fast ../afl-llvm-rt.o ../afl-llvm-rt-32.o ../afl-llvm-rt-64.o ../compare-transform-pass.so ../split-compares-pass.so ../split-switches-pass.so ../cmplog-routines-pass.so ../cmplog-instructions-pass.so
 endif
 
 ifneq "$(CLANGVER)" "$(LLVMVER)"
@@ -222,6 +222,9 @@ afl-common.o: ../src/afl-common.c
 ../cmplog-routines-pass.so:	cmplog-routines-pass.cc | test_deps
 	$(CXX) $(CLANG_CFL) -shared $< -o $@ $(CLANG_LFL)
 
+../cmplog-instructions-pass.so:	cmplog-instructions-pass.cc | test_deps
+	$(CXX) $(CLANG_CFL) -shared $< -o $@ $(CLANG_LFL)
+
 ../afl-llvm-rt.o: afl-llvm-rt.o.c | test_deps
 	$(CC) $(CFLAGS) -fPIC -c $< -o $@
 
diff --git a/llvm_mode/afl-clang-fast.c b/llvm_mode/afl-clang-fast.c
index fe987157..fa534438 100644
--- a/llvm_mode/afl-clang-fast.c
+++ b/llvm_mode/afl-clang-fast.c
@@ -201,50 +201,59 @@ static void edit_params(u32 argc, char** argv) {
 
   if (cmplog_mode) {
 
-    cc_params[cc_par_cnt++] = "-fsanitize-coverage=trace-pc-guard,trace-cmp";
-
     cc_params[cc_par_cnt++] = "-Xclang";
     cc_params[cc_par_cnt++] = "-load";
     cc_params[cc_par_cnt++] = "-Xclang";
     cc_params[cc_par_cnt++] =
         alloc_printf("%s/cmplog-routines-pass.so", obj_path);
-
+    
+    // reuse split switches from laf
+    cc_params[cc_par_cnt++] = "-Xclang";
+    cc_params[cc_par_cnt++] = "-load";
+    cc_params[cc_par_cnt++] = "-Xclang";
+    cc_params[cc_par_cnt++] =
+        alloc_printf("%s/split-switches-pass.so", obj_path);
+    
+    cc_params[cc_par_cnt++] = "-Xclang";
+    cc_params[cc_par_cnt++] = "-load";
+    cc_params[cc_par_cnt++] = "-Xclang";
+    cc_params[cc_par_cnt++] =
+        alloc_printf("%s/cmplog-instructions-pass.so", obj_path);
+        
     cc_params[cc_par_cnt++] = "-fno-inline";
 
-  } else {
+  }
 
 #ifdef USE_TRACE_PC
 
-    cc_params[cc_par_cnt++] =
-        "-fsanitize-coverage=trace-pc-guard";  // edge coverage by default
-    // cc_params[cc_par_cnt++] = "-mllvm";
-    // cc_params[cc_par_cnt++] =
-    // "-fsanitize-coverage=trace-cmp,trace-div,trace-gep";
-    // cc_params[cc_par_cnt++] = "-sanitizer-coverage-block-threshold=0";
+  cc_params[cc_par_cnt++] =
+      "-fsanitize-coverage=trace-pc-guard";  // edge coverage by default
+  // cc_params[cc_par_cnt++] = "-mllvm";
+  // cc_params[cc_par_cnt++] =
+  // "-fsanitize-coverage=trace-cmp,trace-div,trace-gep";
+  // cc_params[cc_par_cnt++] = "-sanitizer-coverage-block-threshold=0";
 #else
-    if (getenv("USE_TRACE_PC") || getenv("AFL_USE_TRACE_PC") ||
-        getenv("AFL_LLVM_USE_TRACE_PC") || getenv("AFL_TRACE_PC")) {
+  if (getenv("USE_TRACE_PC") || getenv("AFL_USE_TRACE_PC") ||
+      getenv("AFL_LLVM_USE_TRACE_PC") || getenv("AFL_TRACE_PC")) {
 
-      cc_params[cc_par_cnt++] =
-          "-fsanitize-coverage=trace-pc-guard";  // edge coverage by default
+    cc_params[cc_par_cnt++] =
+        "-fsanitize-coverage=trace-pc-guard";  // edge coverage by default
 
-    } else {
+  } else {
 
-      cc_params[cc_par_cnt++] = "-Xclang";
-      cc_params[cc_par_cnt++] = "-load";
-      cc_params[cc_par_cnt++] = "-Xclang";
-      if (getenv("AFL_LLVM_INSTRIM") != NULL || getenv("INSTRIM_LIB") != NULL)
-        cc_params[cc_par_cnt++] =
-            alloc_printf("%s/libLLVMInsTrim.so", obj_path);
-      else
-        cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-pass.so", obj_path);
+    cc_params[cc_par_cnt++] = "-Xclang";
+    cc_params[cc_par_cnt++] = "-load";
+    cc_params[cc_par_cnt++] = "-Xclang";
+    if (getenv("AFL_LLVM_INSTRIM") != NULL || getenv("INSTRIM_LIB") != NULL)
+      cc_params[cc_par_cnt++] =
+          alloc_printf("%s/libLLVMInsTrim.so", obj_path);
+    else
+      cc_params[cc_par_cnt++] = alloc_printf("%s/afl-llvm-pass.so", obj_path);
 
-    }
+  }
 
 #endif                                                     /* ^USE_TRACE_PC */
 
-  }
-
   cc_params[cc_par_cnt++] = "-Qunused-arguments";
 
   /* Detect stray -v calls from ./configure scripts. */
diff --git a/llvm_mode/afl-llvm-rt.o.c b/llvm_mode/afl-llvm-rt.o.c
index b3561cb2..bd349504 100644
--- a/llvm_mode/afl-llvm-rt.o.c
+++ b/llvm_mode/afl-llvm-rt.o.c
@@ -399,13 +399,13 @@ void __sanitizer_cov_trace_pc_guard_init(uint32_t* start, uint32_t* stop) {
 
 ///// CmpLog instrumentation
 
-void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2) {
+void __cmplog_ins_hook1(uint8_t Arg1, uint8_t Arg2) {
 
   return;
 
 }
 
-void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) {
+void __cmplog_ins_hook2(uint16_t Arg1, uint16_t Arg2) {
 
   if (!__afl_cmp_map) return;
 
@@ -429,7 +429,7 @@ void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) {
 
 }
 
-void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) {
+void __cmplog_ins_hook4(uint32_t Arg1, uint32_t Arg2) {
 
   if (!__afl_cmp_map) return;
 
@@ -450,7 +450,7 @@ void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) {
 
 }
 
-void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) {
+void __cmplog_ins_hook8(uint64_t Arg1, uint64_t Arg2) {
 
   if (!__afl_cmp_map) return;
 
@@ -472,19 +472,33 @@ void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) {
 }
 
 #if defined(__APPLE__)
-#pragma weak __sanitizer_cov_trace_const_cmp1 = __sanitizer_cov_trace_cmp1
-#pragma weak __sanitizer_cov_trace_const_cmp2 = __sanitizer_cov_trace_cmp2
-#pragma weak __sanitizer_cov_trace_const_cmp4 = __sanitizer_cov_trace_cmp4
-#pragma weak __sanitizer_cov_trace_const_cmp8 = __sanitizer_cov_trace_cmp8
+#pragma weak __sanitizer_cov_trace_const_cmp1 = __cmplog_ins_hook1
+#pragma weak __sanitizer_cov_trace_const_cmp2 = __cmplog_ins_hook2
+#pragma weak __sanitizer_cov_trace_const_cmp4 = __cmplog_ins_hook4
+#pragma weak __sanitizer_cov_trace_const_cmp8 = __cmplog_ins_hook8
+
+#pragma weak __sanitizer_cov_trace_cmp1 = __cmplog_ins_hook1
+#pragma weak __sanitizer_cov_trace_cmp2 = __cmplog_ins_hook2
+#pragma weak __sanitizer_cov_trace_cmp4 = __cmplog_ins_hook4
+#pragma weak __sanitizer_cov_trace_cmp8 = __cmplog_ins_hook8
 #else
 void __sanitizer_cov_trace_const_cmp1(uint8_t Arg1, uint8_t Arg2)
-    __attribute__((alias("__sanitizer_cov_trace_cmp1")));
+    __attribute__((alias("__cmplog_ins_hook1")));
 void __sanitizer_cov_trace_const_cmp2(uint16_t Arg1, uint16_t Arg2)
-    __attribute__((alias("__sanitizer_cov_trace_cmp2")));
+    __attribute__((alias("__cmplog_ins_hook2")));
 void __sanitizer_cov_trace_const_cmp4(uint32_t Arg1, uint32_t Arg2)
-    __attribute__((alias("__sanitizer_cov_trace_cmp4")));
+    __attribute__((alias("__cmplog_ins_hook4")));
 void __sanitizer_cov_trace_const_cmp8(uint64_t Arg1, uint64_t Arg2)
-    __attribute__((alias("__sanitizer_cov_trace_cmp8")));
+    __attribute__((alias("__cmplog_ins_hook8")));
+
+void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2)
+    __attribute__((alias("__cmplog_ins_hook1")));
+void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2)
+    __attribute__((alias("__cmplog_ins_hook2")));
+void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2)
+    __attribute__((alias("__cmplog_ins_hook4")));
+void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2)
+    __attribute__((alias("__cmplog_ins_hook8")));
 #endif                                                /* defined(__APPLE__) */
 
 void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t* Cases) {
diff --git a/llvm_mode/cmplog-instructions-pass.cc b/llvm_mode/cmplog-instructions-pass.cc
new file mode 100644
index 00000000..f6ee4a4c
--- /dev/null
+++ b/llvm_mode/cmplog-instructions-pass.cc
@@ -0,0 +1,398 @@
+/*
+   american fuzzy lop++ - LLVM CmpLog instrumentation
+   --------------------------------------------------
+
+   Written by Andrea Fioraldi <andreafioraldi@gmail.com>
+
+   Copyright 2015, 2016 Google Inc. All rights reserved.
+   Copyright 2019-2020 AFLplusplus Project. All rights reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at:
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <list>
+#include <string>
+#include <fstream>
+#include <sys/time.h>
+#include "llvm/Config/llvm-config.h"
+
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/ValueTracking.h"
+
+#if LLVM_VERSION_MAJOR > 3 || \
+    (LLVM_VERSION_MAJOR == 3 && LLVM_VERSION_MINOR > 4)
+#include "llvm/IR/Verifier.h"
+#include "llvm/IR/DebugInfo.h"
+#else
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/DebugInfo.h"
+#define nullptr 0
+#endif
+
+#include <set>
+
+using namespace llvm;
+
+namespace {
+
+class CmpLogInstructions : public ModulePass {
+
+ public:
+  static char ID;
+  CmpLogInstructions() : ModulePass(ID) {
+
+    char *instWhiteListFilename = getenv("AFL_LLVM_WHITELIST");
+    if (instWhiteListFilename) {
+
+      std::string   line;
+      std::ifstream fileStream;
+      fileStream.open(instWhiteListFilename);
+      if (!fileStream) report_fatal_error("Unable to open AFL_LLVM_WHITELIST");
+      getline(fileStream, line);
+      while (fileStream) {
+
+        myWhitelist.push_back(line);
+        getline(fileStream, line);
+
+      }
+
+    }
+
+  }
+
+  bool runOnModule(Module &M) override;
+
+#if LLVM_VERSION_MAJOR < 4
+  const char *getPassName() const override {
+
+#else
+  StringRef getPassName() const override {
+
+#endif
+    return "cmplog instructions";
+
+  }
+
+ protected:
+  std::list<std::string> myWhitelist;
+
+ private:
+  bool hookInstrs(Module &M);
+
+};
+
+}  // namespace
+
+char CmpLogInstructions::ID = 0;
+
+bool CmpLogInstructions::hookInstrs(Module &M) {
+
+  std::vector<Instruction *> icomps;
+  LLVMContext &           C = M.getContext();
+
+  Type *       VoidTy = Type::getVoidTy(C);
+  IntegerType *           Int8Ty = IntegerType::getInt8Ty(C);
+  IntegerType *           Int16Ty = IntegerType::getInt16Ty(C);
+  IntegerType *           Int32Ty = IntegerType::getInt32Ty(C);
+  IntegerType *           Int64Ty = IntegerType::getInt64Ty(C);
+  
+#if LLVM_VERSION_MAJOR < 9
+  Constant *
+#else
+  FunctionCallee
+#endif
+      c1 = M.getOrInsertFunction("__cmplog_ins_hook1", VoidTy, Int8Ty, Int8Ty
+#if LLVM_VERSION_MAJOR < 5
+                                ,
+                                NULL
+#endif
+      );
+#if LLVM_VERSION_MAJOR < 9
+  Function *cmplogHookIns1 = cast<Function>(c1);
+#else
+  FunctionCallee cmplogHookIns1 = c1;
+#endif
+
+#if LLVM_VERSION_MAJOR < 9
+  Constant *
+#else
+  FunctionCallee
+#endif
+      c2 = M.getOrInsertFunction("__cmplog_ins_hook2", VoidTy, Int16Ty, Int16Ty
+#if LLVM_VERSION_MAJOR < 5
+                                ,
+                                NULL
+#endif
+      );
+#if LLVM_VERSION_MAJOR < 9
+  Function *cmplogHookIns2 = cast<Function>(c2);
+#else
+  FunctionCallee cmplogHookIns2 = c2;
+#endif
+
+#if LLVM_VERSION_MAJOR < 9
+  Constant *
+#else
+  FunctionCallee
+#endif
+      c4 = M.getOrInsertFunction("__cmplog_ins_hook4", VoidTy, Int32Ty, Int32Ty
+#if LLVM_VERSION_MAJOR < 5
+                                ,
+                                NULL
+#endif
+      );
+#if LLVM_VERSION_MAJOR < 9
+  Function *cmplogHookIns4 = cast<Function>(c4);
+#else
+  FunctionCallee cmplogHookIns4 = c4;
+#endif
+
+#if LLVM_VERSION_MAJOR < 9
+  Constant *
+#else
+  FunctionCallee
+#endif
+      c8 = M.getOrInsertFunction("__cmplog_ins_hook8", VoidTy, Int64Ty, Int64Ty
+#if LLVM_VERSION_MAJOR < 5
+                                ,
+                                NULL
+#endif
+      );
+#if LLVM_VERSION_MAJOR < 9
+  Function *cmplogHookIns8 = cast<Function>(c8);
+#else
+  FunctionCallee cmplogHookIns8 = c8;
+#endif
+
+  /* iterate over all functions, bbs and instruction and add suitable calls */
+  for (auto &F : M) {
+
+    for (auto &BB : F) {
+
+      if (!myWhitelist.empty()) {
+
+        BasicBlock::iterator IP = BB.getFirstInsertionPt();
+
+        bool instrumentBlock = false;
+
+        /* Get the current location using debug information.
+         * For now, just instrument the block if we are not able
+         * to determine our location. */
+        DebugLoc Loc = IP->getDebugLoc();
+#if LLVM_VERSION_MAJOR >= 4 || \
+    (LLVM_VERSION_MAJOR == 3 && LLVM_VERSION_MINOR >= 7)
+        if (Loc) {
+
+          DILocation *cDILoc = dyn_cast<DILocation>(Loc.getAsMDNode());
+
+          unsigned int instLine = cDILoc->getLine();
+          StringRef    instFilename = cDILoc->getFilename();
+
+          if (instFilename.str().empty()) {
+
+            /* If the original location is empty, try using the inlined location
+             */
+            DILocation *oDILoc = cDILoc->getInlinedAt();
+            if (oDILoc) {
+
+              instFilename = oDILoc->getFilename();
+              instLine = oDILoc->getLine();
+
+            }
+
+          }
+
+          (void)instLine;
+
+          /* Continue only if we know where we actually are */
+          if (!instFilename.str().empty()) {
+
+            for (std::list<std::string>::iterator it = myWhitelist.begin();
+                 it != myWhitelist.end(); ++it) {
+
+              /* We don't check for filename equality here because
+               * filenames might actually be full paths. Instead we
+               * check that the actual filename ends in the filename
+               * specified in the list. */
+              if (instFilename.str().length() >= it->length()) {
+
+                if (instFilename.str().compare(
+                        instFilename.str().length() - it->length(),
+                        it->length(), *it) == 0) {
+
+                  instrumentBlock = true;
+                  break;
+
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+#else
+        if (!Loc.isUnknown()) {
+
+          DILocation cDILoc(Loc.getAsMDNode(C));
+
+          unsigned int instLine = cDILoc.getLineNumber();
+          StringRef    instFilename = cDILoc.getFilename();
+
+          (void)instLine;
+
+          /* Continue only if we know where we actually are */
+          if (!instFilename.str().empty()) {
+
+            for (std::list<std::string>::iterator it = myWhitelist.begin();
+                 it != myWhitelist.end(); ++it) {
+
+              /* We don't check for filename equality here because
+               * filenames might actually be full paths. Instead we
+               * check that the actual filename ends in the filename
+               * specified in the list. */
+              if (instFilename.str().length() >= it->length()) {
+
+                if (instFilename.str().compare(
+                        instFilename.str().length() - it->length(),
+                        it->length(), *it) == 0) {
+
+                  instrumentBlock = true;
+                  break;
+
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+#endif
+
+        /* Either we couldn't figure out our location or the location is
+         * not whitelisted, so we skip instrumentation. */
+        if (!instrumentBlock) continue;
+
+      }
+
+      for (auto &IN : BB) {
+
+        CmpInst *selectcmpInst = nullptr;
+
+        if ((selectcmpInst = dyn_cast<CmpInst>(&IN))) {
+
+          if (selectcmpInst->getPredicate() == CmpInst::ICMP_EQ ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_NE ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_UGT ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_SGT ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_ULT ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_SLT ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_UGE ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_SGE ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_ULE ||
+              selectcmpInst->getPredicate() == CmpInst::ICMP_SLE) {
+
+            auto op0 = selectcmpInst->getOperand(0);
+            auto op1 = selectcmpInst->getOperand(1);
+
+            IntegerType *intTyOp0 = dyn_cast<IntegerType>(op0->getType());
+            IntegerType *intTyOp1 = dyn_cast<IntegerType>(op1->getType());
+
+            /* this is probably not needed but we do it anyway */
+            if (!intTyOp0 || !intTyOp1) { continue; }
+
+            icomps.push_back(selectcmpInst);
+
+          }
+
+        }
+
+      }
+
+    }
+
+  }
+
+  if (!icomps.size()) return false;
+  errs() << "Hooking " << icomps.size() << " cmp instructions\n";
+
+  for (auto &selectcmpInst : icomps) {
+  
+    IRBuilder<> IRB(selectcmpInst->getParent());
+    IRB.SetInsertPoint(selectcmpInst);
+
+    auto op0 = selectcmpInst->getOperand(0);
+    auto op1 = selectcmpInst->getOperand(1);
+    
+    IntegerType *intTyOp0 = dyn_cast<IntegerType>(op0->getType());
+    IntegerType *intTyOp1 = dyn_cast<IntegerType>(op1->getType());
+
+    unsigned max_size = intTyOp0->getBitWidth() > intTyOp1->getBitWidth() ?
+                        intTyOp0->getBitWidth() : intTyOp1->getBitWidth();
+
+    std::vector<Value *> args;
+    args.push_back(op0);
+    args.push_back(op1);
+
+    switch (max_size) {
+      case 8: IRB.CreateCall(cmplogHookIns1, args, "tmp"); break;
+      case 16: IRB.CreateCall(cmplogHookIns2, args, "tmp"); break;
+      case 32: IRB.CreateCall(cmplogHookIns4, args, "tmp"); break;
+      case 64: IRB.CreateCall(cmplogHookIns8, args, "tmp"); break;
+      default: break;
+    }
+
+  }
+
+  return true;
+
+}
+
+bool CmpLogInstructions::runOnModule(Module &M) {
+
+  if (getenv("AFL_QUIET") == NULL)
+    llvm::errs()
+        << "Running cmplog-instructions-pass by andreafioraldi@gmail.com\n";
+  hookInstrs(M);
+  verifyModule(M);
+
+  return true;
+
+}
+
+static void registerCmpLogInstructionsPass(const PassManagerBuilder &,
+                                       legacy::PassManagerBase &PM) {
+
+  auto p = new CmpLogInstructions();
+  PM.add(p);
+
+}
+
+static RegisterStandardPasses RegisterCmpLogInstructionsPass(
+    PassManagerBuilder::EP_OptimizerLast, registerCmpLogInstructionsPass);
+
+static RegisterStandardPasses RegisterCmpLogInstructionsPass0(
+    PassManagerBuilder::EP_EnabledOnOptLevel0, registerCmpLogInstructionsPass);
+
diff --git a/src/afl-fuzz-redqueen.c b/src/afl-fuzz-redqueen.c
index 19fc51f0..d6f117f6 100644
--- a/src/afl-fuzz-redqueen.c
+++ b/src/afl-fuzz-redqueen.c
@@ -118,8 +118,8 @@ u8 colorization(u8* buf, u32 len, u32 exec_cksum) {
   stage_max = 1000;
 
   struct range* rng;
-  stage_cur = stage_max;
-  while ((rng = pop_biggest_range(&ranges)) != NULL && stage_cur) {
+  stage_cur = 0;
+  while ((rng = pop_biggest_range(&ranges)) != NULL && stage_cur < stage_max) {
 
     u32 s = rng->end - rng->start;
     if (s == 0) goto empty_range;
@@ -142,15 +142,15 @@ u8 colorization(u8* buf, u32 len, u32 exec_cksum) {
 
   empty_range:
     ck_free(rng);
-    --stage_cur;
+    ++stage_cur;
 
   }
 
-  if (stage_cur) queue_cur->fully_colorized = 1;
+  if (stage_cur < stage_max) queue_cur->fully_colorized = 1;
 
   new_hit_cnt = queued_paths + unique_crashes;
   stage_finds[STAGE_COLORIZATION] += new_hit_cnt - orig_hit_cnt;
-  stage_cycles[STAGE_COLORIZATION] += stage_max - stage_cur;
+  stage_cycles[STAGE_COLORIZATION] += stage_cur;
   ck_free(backup);
 
   while (ranges) {