Program: CWE-787
Project: CVE-2020-28371
Buggy source:
/* Copyright (c) 2008-2015, Avian Contributors

   Permission to use, copy, modify, and/or distribute this software
   for any purpose with or without fee is hereby granted, provided
   that the above copyright notice and this permission notice appear
   in all copies.

   There is NO WARRANTY for this software.  See license.txt for
   details. */

package java.io;

public class FileOutputStream extends OutputStream {
  //   static {
  //     System.loadLibrary("natives");
  //   }

  private int fd;

  public FileOutputStream(FileDescriptor fd) {
    this.fd = fd.value;
  }

  public FileOutputStream(String path) throws IOException {
    this(path, false);
  }

  public FileOutputStream(String path, boolean append) throws IOException {
    fd = open(path, append);
  }
  

  public FileOutputStream(File file) throws IOException {
    this(file.getPath());
  }

  private static native int open(String path, boolean append) throws IOException;

  private static native void write(int fd, int c) throws IOException;

  private static native void write(int fd, byte[] b, int offset, int length)
    throws IOException;

  private static native void close(int fd) throws IOException;

  public void write(int c) throws IOException {
    write(fd, c);
  }

  public void write(byte[] b, int offset, int length) throws IOException {
    if (b == null) {
      throw new NullPointerException();
    }

    if (offset < 0 || offset + length > b.length) {
      throw new ArrayIndexOutOfBoundsException();
    }

    write(fd, b, offset, length);
  }

  public void close() throws IOException {
    if (fd != -1) {
      close(fd);
      fd = -1;
    }
  }
}


Fixed version (ground truth):
/* Copyright (c) 2008-2015, Avian Contributors

   Permission to use, copy, modify, and/or distribute this software
   for any purpose with or without fee is hereby granted, provided
   that the above copyright notice and this permission notice appear
   in all copies.

   There is NO WARRANTY for this software.  See license.txt for
   details. */

package java.io;

public class FileOutputStream extends OutputStream {
  //   static {
  //     System.loadLibrary("natives");
  //   }

  private int fd;

  public FileOutputStream(FileDescriptor fd) {
    this.fd = fd.value;
  }

  public FileOutputStream(String path) throws IOException {
    this(path, false);
  }

  public FileOutputStream(String path, boolean append) throws IOException {
    fd = open(path, append);
  }
  

  public FileOutputStream(File file) throws IOException {
    this(file.getPath());
  }

  private static native int open(String path, boolean append) throws IOException;

  private static native void write(int fd, int c) throws IOException;

  private static native void write(int fd, byte[] b, int offset, int length)
    throws IOException;

  private static native void close(int fd) throws IOException;

  public void write(int c) throws IOException {
    write(fd, c);
  }

  public void write(byte[] b, int offset, int length) throws IOException {
    if (b == null) {
      throw new NullPointerException();
    }

    if (offset < 0 || length < 0 || length > b.length || offset > b.length - length) {
      throw new ArrayIndexOutOfBoundsException();
    }

    write(fd, b, offset, length);
  }

  public void close() throws IOException {
    if (fd != -1) {
      close(fd);
      fd = -1;
    }
  }
}