diff --git a/pmu/pfm/uncore.cpp b/pmu/pfm/uncore.cpp
index 674e14f748417eb3bd3bbbad3ea405cd4291df74..9c2d9b0dc1330d2d7d5302ac4921e600b5392242 100644
--- a/pmu/pfm/uncore.cpp
+++ b/pmu/pfm/uncore.cpp
@@ -133,12 +133,15 @@ int FillUncoreFields(const char* pmuName, PmuEvt *evt)
 bool CheckUncoreRawEvent(const char *pmuName)
 {
     string strName = pmuName;
+    auto findSlash = strName.find('/');
+    if (findSlash == string::npos) {
+        return false;
+    }
     unsigned numEvt;
     auto eventList = PmuEventList(UNCORE_EVENT, &numEvt);
     if (eventList == nullptr) {
         return false;
     }
-    auto findSlash = strName.find('/');
     string devName = strName.substr(0, findSlash);
     string evtName = strName.substr(devName.size() + 1, strName.size() - 1 - (devName.size() + 1));
     // check if "config=" at back part of pmuName
diff --git a/symbol/symbol_resolve.cpp b/symbol/symbol_resolve.cpp
index b44cfffee12dce3146f5bb4cbec459d733eea755..504e526b43ae1ee80f55bbf3db1a3886eda13c0b 100644
--- a/symbol/symbol_resolve.cpp
+++ b/symbol/symbol_resolve.cpp
@@ -767,7 +767,7 @@ void SymbolResolve::SearchDwarfInfo(MyDwarf& myDwarf, unsigned long addr, struct
         strcpy(symbol->fileName, dwarfEntry.fileName.c_str());
         symbol->lineNum = dwarfEntry.lineNum;
     } else {
-        strcpy(symbol->fileName, "Uknown");
+        strcpy(symbol->fileName, "UKNOWN");
         symbol->lineNum = 0;
     }
 }
@@ -891,10 +891,15 @@ struct Symbol* SymbolResolve::MapUserAddr(int pid, unsigned long addr)
             addrToSearch = addrToSearch - module->start;
         }
         this->SearchElfInfo(myElf, addrToSearch, symbol, &symbol->offset);  
+    } else {
+        strcpy(symbol->symbolName, "UNKNOWN");
     }
 
     if (this->dwarfMap.find(module->moduleName) != this->dwarfMap.end()) {
         this->SearchDwarfInfo(this->dwarfMap.at(module->moduleName), addrToSearch, symbol);
+    } else {
+        strcpy(symbol->fileName, "UKNOWN");
+        symbol->lineNum = 0;
     }
     symbol->codeMapAddr = addrToSearch;
     this->symbolMap.at(pid).insert({addr, symbol});