IOCTL problem sending string value to usermode app

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C++

Windows

kernel

I am creating a kernel mode driver that monitors process creation and sends information about it to the C# application. The information that should be passed is ProcessID and ProcessPath. At this point, the driver only sends ProcessID to the C# application, while I don't know how to send ProcessPath. I tried the GetProcessPathFromDriver() moetode given below in my code, but the returned string is Chinese characters. I am not advanced in kernel mode driver programming, so please help.

What I have tried:

Driver code:

ULONG ProcID;
PUNICODE_STRING ProcPath;

void sCreateProcessNotifyRoutineEx(PEPROCESS process, HANDLE pid, PPS_CREATE_NOTIFY_INFO createInfo)
{
	UNREFERENCED_PARAMETER(process);
	UNREFERENCED_PARAMETER(pid);

	if (createInfo != NULL)
	{
		ProcID = HandleToUlong(pid);
		ProcPath = createInfo->ImageFileName;
	}
}

NTSTATUS HandleCustomIOCTL(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
	UNREFERENCED_PARAMETER(DeviceObject);
	PIO_STACK_LOCATION stackLocation = NULL;
	PIO_STACK_LOCATION irpsp = IoGetCurrentIrpStackLocation(Irp);
	PVOID* buffer = Irp->AssociatedIrp.SystemBuffer;
	ULONG outLength = irpsp->Parameters.DeviceIoControl.OutputBufferLength;
	ULONG returnLength = 0;

	stackLocation = IoGetCurrentIrpStackLocation(Irp);
	if (stackLocation->Parameters.DeviceIoControl.IoControlCode == GET_PROCESS_PID)
	{
		// Send process PID to user
		Irp->AssociatedIrp.SystemBuffer = ProcID;
		Irp->IoStatus.Information = sizeof(Irp->AssociatedIrp.SystemBuffer);
	}
	if (stackLocation->Parameters.DeviceIoControl.IoControlCode == GET_PROCESS_PATH)
	{
		// Send process Path to user
		RtlFillMemory(buffer, outLength, 0);
		RtlCopyBytes(buffer, ProcPath->Buffer, ProcPath->Length * 2);
		Irp->IoStatus.Status = STATUS_SUCCESS;
		returnLength = ProcPath->Length * 2;
	}
	Irp->IoStatus.Status = STATUS_SUCCESS;
	IoCompleteRequest(Irp, IO_NO_INCREMENT);
	return STATUS_SUCCESS;
}

C# app code:

public void GetProcessPathFromDriver()
        {
            const int MAX_STRING_SIZE = 64;
            int numStringBytes = (MAX_STRING_SIZE + 1) * 2;
            IntPtr p = Marshal.AllocHGlobal(numStringBytes);
            DeviceIoControl(driverHandle, DriverOperations.GET_PROCESS_PATH, IntPtr.Zero, 0, p, numStringBytes, IntPtr.Zero, IntPtr.Zero);
            String final = Marshal.PtrToStringUni(p);
            if (System.IO.File.Exists(final))
            {
                MessageBox.Show("Recieved Path from kernel: " + final);
            }
            Marshal.FreeHGlobal(p);
        }