Panel added to BorderLayout.CENTER does not occupy

I am currently learning to program GUI in Java, and I have a problem where the CENTER component does not occupy the remaining space in the frame. From what I've read BorderLayout will grant components in north/south their preferred height and the stretch it out to the edges, and west/east will be the opposite. The center component will then get whatever space is left. What I am trying to do is to create a simple window with a panel in the north region, and a panel in the center region. I give each their own background color so I can easily see the space they are given. However, instead of getting a window with a yellow top bar and the remaining space being occupied by the magenta panel, I get this.

The top panel is just a regular JPanel, but the center panel is a class extending JPanel which overrides paintComponent and fills the panel with a color. If I hardcode in a bigger area in the fillRect() it will actually fill the window. So I suspect there's something wrong happening when I call getHeight() and getWidth in the method. It also might be worth mentioning that the dawPanel always will paint a perfect square, if I resize the window into a rectangle longer on the Y-aksis the gap will appear on the bottom instead.

So my question is, how can I get the component added to the Borderlayout.CENTER to occupy all remaining space in the frame.contentPane()?

package oblig1;
import java.awt.*;
import javax.swing.*;

public class Oblig1 
{
    JFrame frame;
    JPanel infoPanel;
    DrawingPanel drawPanel;

    public static void main(String[] args) 
    {
        Oblig1 game = new Oblig1();
    }

    public Oblig1()
    {
        frame = new JFrame("Parachute Game");
        frame.setSize(860, 640);
        infoPanel = new JPanel();
        drawPanel = new DrawingPanel();

        infoPanel.setBackground(Color.yellow);
        infoPanel.setPreferredSize(new Dimension(840, 20));
        infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));

        drawPanel.setPreferredSize(new Dimension(840, 620));

        frame.getContentPane().add(infoPanel, BorderLayout.NORTH);
        frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//      frame.setResizable(false);
        frame.setVisible(true);
    }

    //This class represents the panel that paints all animated parts of the game
    public class DrawingPanel extends JPanel
    {
        public DrawingPanel()
        {
            setDoubleBuffered(true);
        }

        @Override
        protected void paintComponent(Graphics g)
        {
            Graphics2D g2d = (Graphics2D) g;
            g2d.setColor(Color.MAGENTA);

            g2d.fillRect(0, 0, drawPanel.getHeight(), drawPanel.getWidth());
        }
    }
}

issue came from two code lines (and one code line missed

infoPanel.setPreferredSize(new Dimension(840, 20));

and
infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));

BoxLayout required Min, Max and PreferredSize, otherwise missed Dimensions collided with another PreferredSize, in this case (infoPanel.setPreferredSize(new Dimension(840, 20)); ) that is laid in JFrame that uses BorderLayout
remove infoPanel.setPreferredSize(new Dimension(840, 20));, or its widht must be less than PreferredSize used for JPanel
painting in Swing by default never returns PreferredSize correctly back to the container, you jave to override getPreferredSize, for BoxLayout min, max and preferred size
use JFrame.pack() instead of sizing for min,max and preferredSize directly to the JComponents or container, nor to setSize for JFrame
not true at all, to see my EDIT --> use another LayoutManager for JPanel to reduce funny issue with painting if is JFrame resized
your paintComponent missed important code line super.paintComponent(g);

e.g.

import java.awt.*;
import javax.swing.*;

public class Oblig1 {

    JFrame frame;
    JPanel infoPanel;
    DrawingPanel drawPanel;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Oblig1();
            }
        });
    }

    public Oblig1() {
        frame = new JFrame("Parachute Game");
        //frame.setSize(860, 640);
        infoPanel = new JPanel() {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(20, 20);
            }
        };
        drawPanel = new DrawingPanel();

        infoPanel.setBackground(Color.yellow);
        //drawPanel.setPreferredSize(new Dimension(840, 20));
        infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));
        //drawPanel.setPreferredSize(new Dimension(840, 620));
        frame.getContentPane().add(infoPanel, BorderLayout.NORTH);
        frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//      frame.setResizable(false);
        frame.pack();
        frame.setVisible(true);
    }

    //This class represents the panel that paints all animated parts of the game
    public class DrawingPanel extends JPanel {

        private static final long serialVersionUID = 1L;

        public DrawingPanel() {
            setDoubleBuffered(true);
        }

        @Override
        public Dimension getMinimumSize() {
            return new Dimension(300, 300);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(300, 300);
        }

        @Override
        public Dimension getMaximumSize() {
            return new Dimension(300, 300);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.setColor(Color.MAGENTA);
            //g2d.fillRect(0, 0, getHeight(), getWidth());
            g2d.fillRect(0, 0, getWidth(), getHeight());
        }
    }
}

EDIT

to my point, is simple wrong

use another LayoutManager for JPanel to reduce funny issue with painting if is JFrame resized
there are wrong, reversed parameters for Height and Width, wrong code line g2d.fillRect(0, 0, getHeight(), getWidth()); should be g2d.fillRect(0, 0, getWidth(), getHeight());