如何取消等待SerialPort.BaseStream.ReadAsync？

Question

My c# WinForms application reading asynchronously from serial port. It works, but when the port closes, an StackOverflowException appears. The Call Stack is overflowed with line await ReadAsync(serialPort) on the end of ReadAsync . My guess is the line await ReadAsync still run even though I close SeriaPort, keepReading flag and checking serialPort.IsOpen .
Hence the question, how to cancel await ReadAsync, is it possible? Appreciate some help here because I'm beginner.

public async Task ReadAsync(SerialPort serialPort)
    {

            if (serialPort.IsOpen && keepReading)
            {
                try
                {
                        byte[] buffer = new byte[1];
                        await serialPort.BaseStream.ReadAsync(buffer, 0, 1);
                        content += serialPort.Encoding.GetString(buffer);
                        //do sth with content
                        buffer = null;

                }
                catch (Exception exc)
                {
                    MessageBox.Show(exc.Message);
                }
                if (keepReading && serialPort.IsOpen)
                    await ReadAsync(serialPort);
            }
    }
private async void Button_Click(object sender, EventArgs e)
    {

        if (serialPort.IsOpen)
        {
            keepReading = false;
            serialPort.Dispose();
            serialPort.Close();
        }
        else
        {
            Open();
            keepReading = true;
            if (serialPort.IsOpen)
            {
                serialPort.DiscardOutBuffer();
                serialPort.DiscardInBuffer();
                await ReadAsync(serialPort);
            }
        }
    }

Answer 1

Try to wrap serialPort.BaseStream.ReadAsync(buffer, 0, 1); into another async method and use Task Cancellation to cancel this method before you close the serial port. Cancel an Async Task or a List of Tasks (C#)