SetupDiGetDeviceInstanceId Run time Error (Access Violation)

Question

Im Trying to get the Instance ID of USB Device using the SetupDi API using the c++.

So for this I used SetupDiGetClassDevs -> SetupDiEnumDeviceInfo -> SetupDiGetDeviceInstanceId to get the instance ID.

but while debugging I'm getting the error as below

Exception thrown at 0x761EA543 (setupapi.dll) in setupDi_example.exe: 0xC0000005: Access violation reading location 0xCCCCCCCC.

ZeroMemory(&devInfoData, sizeof(devInfoData));  
            devInfoData.cbSize = sizeof(devInfoData);  
            pDevDetail = (PSP_DEVINFO_DATA)buffer;  
            pDevDetail->cbSize = sizeof(SP_DEVINFO_DATA);  
            PTSTR buf = NULL;  
            DWORD bufSize = 0;  
            DWORD reqSize = 0;  
              
            if (!SetupDiGetDeviceInstanceId(hDevInfo, pDevDetail, buf, bufSize, &reqSize))  
            {  
                if (bufSize < reqSize)  
                {  
                    if (NULL != buf)  
                    {  
                        delete[] buf;  
                        buf = NULL;  
                        bufSize = 0;  
                    }  
                    buf = new TCHAR[reqSize];  
                    if (NULL == buf)  
                    {  
                        cout << "Insufficient memory" << endl;  
                        break;  
                    }  
                    bufSize = reqSize;  
                    if (!SetupDiGetDeviceInstanceId(hDevInfo, pDevDetail, buf, bufSize, &reqSize))  
                        cout << "Error in SetUpDiGetDeviceInstanceID " << GetLastError() << endl;  
                    else  
                        cout <<"Instance ID "<< buf << endl;  
                }  
                else  
                {  
                    cout << "Error in SetUpDiGetDeviceInstanceID " << GetLastError() << endl;  
                    break;  
                }  
            }  
  

Answer 1

This test works on my PC (Windows 10 21H1, VS 2022) =>

                SP_DEVINFO_DATA did;  
                DWORD nIndex = 0;  
                HDEVINFO hDI = SetupDiGetClassDevs(&GUID_DEVINTERFACE_USB_DEVICE, NULL, NULL, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT);  
                LPTSTR pwszInstanceId = (LPTSTR)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, (MAX_DEVICE_ID_LEN * sizeof(WCHAR)));  
                if ((NULL != pwszInstanceId) && (INVALID_HANDLE_VALUE != hDI))  
                {  
                    while (did.cbSize = sizeof(SP_DEVINFO_DATA), SetupDiEnumDeviceInfo(hDI, nIndex, &did))  
                    {  
                        bool bSuccess = SetupDiGetDeviceInstanceId(hDI, &did, pwszInstanceId, MAX_DEVICE_ID_LEN, NULL);  
                        if (bSuccess)  
                        {  
                            // Code...  
                        }  
                        nIndex++;  
                    }  
                    SetupDiDestroyDeviceInfoList(hDI);  
                }  
                if (pwszInstanceId)  
                    HeapFree(GetProcessHeap(), 0, pwszInstanceId);