adding ctor function skipping in LTO fixed map mode

1 files changed, 63 insertions, 13 deletions

diff --git a/llvm_mode/afl-llvm-lto-instrumentation.so.cc b/llvm_mode/afl-llvm-lto-instrumentation.so.cc
index abc836aa..fd8e48a7 100644
--- a/llvm_mode/afl-llvm-lto-instrumentation.so.cc
+++ b/llvm_mode/afl-llvm-lto-instrumentation.so.cc
@@ -224,22 +224,70 @@ bool AFLLTOPass::runOnModule(Module &M) {
   if (map_addr) {
 
     for (GlobalIFunc &IF : M.ifuncs()) {
-    
+
       StringRef ifunc_name = IF.getName();
       Constant *r = IF.getResolver();
       StringRef r_name = cast<Function>(r->getOperand(0))->getName();
       if (!be_quiet)
-        fprintf(stderr, "Found an ifunc with name %s that  points to resolver function %s, we cannot instrument this, putting it into a block list.\n",
+        fprintf(stderr,
+                "Warning: Found an ifunc with name %s that points to resolver "
+                "function %s, we cannot instrument this, putting it into a "
+                "block list.\n",
                 ifunc_name.str().c_str(), r_name.str().c_str());
-
       module_block_list.push_back(r_name.str());
 
     }
 
-    // next up: ctors run before __afl_init()
-    
-    // TODO
+    GlobalVariable *GV = M.getNamedGlobal("llvm.global_ctors");
+    if (GV && !GV->isDeclaration() && !GV->hasLocalLinkage()) {
+
+      ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
+
+      if (InitList) {
+
+        for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
+
+          if (ConstantStruct *CS =
+                  dyn_cast<ConstantStruct>(InitList->getOperand(i))) {
+
+            if (CS->getNumOperands() >= 2) {
 
+              if (CS->getOperand(1)->isNullValue())
+                break;  // Found a null terminator, stop here.
+
+              ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
+              int          Priority = CI ? CI->getSExtValue() : 0;
+
+              Constant *FP = CS->getOperand(1);
+              if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
+                if (CE->isCast()) FP = CE->getOperand(0);
+              if (Function *F = dyn_cast<Function>(FP)) {
+
+                if (!F->isDeclaration() &&
+                    strncmp(F->getName().str().c_str(), "__afl", 5) != 0 &&
+                    Priority <= 5) {
+
+                  if (!be_quiet)
+                    fprintf(stderr,
+                            "Warning: Found constructor function %s with prio "
+                            "%u, we cannot instrument this, putting it into a "
+                            "block list.\n",
+                            F->getName().str().c_str(), Priority);
+                  module_block_list.push_back(F->getName().str());
+
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+      }
+
+    }
 
   }
 
@@ -260,21 +308,23 @@ bool AFLLTOPass::runOnModule(Module &M) {
     if (isIgnoreFunction(&F)) continue;
 
     if (module_block_list.size()) {
-    
+
       for (auto bname : module_block_list) {
 
         std::string fname = F.getName().str();
 
         if (fname.compare(bname) == 0) {
-        
+
           if (!be_quiet)
-            WARNF("Skipping instrumentation of ifunc resolver function %s",
-                  fname.c_str());
-        
+            WARNF(
+                "Skipping instrumentation of dangerous early running function "
+                "%s",
+                fname.c_str());
+
         }
-      
+
       }
-    
+
     }
 
     // the instrument file list check