heap corrupt when convert Intptr in C# to char* in C++ DLL

Question

I'm trying to convert an array to DLL and modify the values in it.It goes well and the values in array changed.But the problem is,it cause a heap corruption that sometimes it thows out an AccessViolationException,other times the program crash at random

function in DLL code in C++:

MCUPROTOCOL_API int funMcuReadEEprom(const char bank, unsigned char page, char* EEprom,int DataSize)
{   
    st_PROTOCOL stResponsePackage;
    RS232_AT_COMMAND Command;
    memset(Command.szCommand, 0x00, sizeof(Command.szCommand));
    unsigned char Package[8] = { 0x00 };
    unsigned char ResponsePackage[32] = { 0x00 };
    unsigned char Data[2] = { 0x00 };
    int State;
    int ResponsePackageLen;
    Data[0] = bank;
    Data[1] = page;
    fun_ProducePackage(TEST_READ_SOFTWARE_VERSION, Data, Package);
    memcpy(Command.szCommand, Package, sizeof(Package));
    Command.dwLength = sizeof(Package);
    Uart.WriteByte(Command);
    Sleep(200);
    State = Uart.ReadByte((char *)ResponsePackage, &ResponsePackageLen);
    if (ERROR_SUCCESS != State)
    {
        return FAIL_UART;
    }
    State = fun_AnalyzeResponsePackage(ResponsePackageLen, ResponsePackage, &stResponsePackage);
    if (ERROR_SUCCESS != State)
    {
        return State;
    }
    //memcpy(EEprom, stResponsePackage.data, DataSize);
    return SUCCESS;
}

C#:

[DllImport("McuProtocol.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int funMcuReadEEprom(byte bank, byte page, IntPtr EEprom, int DataSize);

and I call it like this:

                byte page = 129;
                byte bank = 2;
                string TransferStr = "";
                IntPtr SoftwareVersion;
                byte[] transfer = new byte[20];
                SoftwareVersion = Marshal.StringToCoTaskMemAuto(TransferStr);
                McuProtocolApi.funMcuRegister(int.Parse(Info.UartCom.Substring(3)), int.Parse(Info.UartBaud));
                McuProtocolApi.funMcuReadEEprom(bank, page, SoftwareVersion, SoftwareVersionSize);
                McuProtocolApi.funMcuRelease();
                transfer = System.Text.Encoding.Unicode.GetBytes(Marshal.PtrToStringAuto(SoftwareVersion, SoftwareVersionSize / 2));
                TransferStr = System.Text.Encoding.UTF8.GetString(transfer);
                StrSW = TransferStr;

If I annotate funMcuReadEEprom ,the program went well,otherwise,when it reach this line,the Program would crash.

EDIT 1: I optimized the code by the suggestions in the comment and the problem still exist.

                byte page = 128;
                byte bank = 2;
                string TransferStr;
                IntPtr SoftwareVersion = Marshal.AllocHGlobal(100);
                byte[] transfer = new byte[20];

            McuProtocolApi.funMcuRegister(int.Parse(Info.UartCom.Substring(3)), int.Parse(Info.UartBaud));
                McuProtocolApi.funMcuReadEEprom(bank, page, SoftwareVersion, SoftwareVersionSize);
                McuProtocolApi.funMcuRelease();


                transfer = System.Text.Encoding.Unicode.GetBytes(Marshal.PtrToStringAuto(SoftwareVersion, SoftwareVersionSize / 2));
                TransferStr = System.Text.Encoding.UTF8.GetString(transfer);
                StrSW = TransferStr;
                Marshal.FreeHGlobal(SoftwareVersion);