Program: 34940
Project: 34940
Buggy source:
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
  boolean isMultipart=ServletFileUpload.isMultipartContent(request);
  if (isMultipart) {
    FileItemFactory factory=new DiskFileItemFactory();
    ServletFileUpload upload=new ServletFileUpload(factory);
    String to=null;
    InputStream fileStream=null;
    try {
      upload.setFileSizeMax(50 * 1024 * 1024);
      List items=upload.parseRequest(request);
      Iterator iterator=items.iterator();
      while (iterator.hasNext()) {
        FileItem item=(FileItem)iterator.next();
        String name=item.getFieldName();
        InputStream stream=item.getInputStream();
        if (item.isFormField()) {
          if (name.equals("String_Node_Str")) {
            to=Streams.asString(stream);
          }
        }
 else         if (name.equals("String_Node_Str")) {
          fileStream=stream;
        }
      }
      if (to == null || fileStream == null) {
        throw new RuntimeException("String_Node_Str");
      }
      File file=new File(to);
      if (file.isDirectory()) {
        throw new IllegalArgumentException("String_Node_Str" + to + "String_Node_Str");
      }
      if (file.exists()) {
        if (!file.delete() || !file.createNewFile()) {
          throw new Exception("String_Node_Str");
        }
      }
 else       if (!file.getParentFile().mkdirs() || !file.createNewFile()) {
        throw new Exception("String_Node_Str");
      }
      if (!file.canWrite()) {
        throw new Exception("String_Node_Str");
      }
      OutputStream dst=new FileOutputStream(file);
      Streams.copy(fileStream,dst,true);
      response.getWriter().write("String_Node_Str");
    }
 catch (    Exception e) {
      System.out.print(e.getMessage());
      response.getWriter().write("String_Node_Str");
      throw new ServletException(e.getMessage(),e);
    }
  }
}

Fixed version (ground truth):
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
  boolean isMultipart=ServletFileUpload.isMultipartContent(request);
  if (isMultipart) {
    FileItemFactory factory=new DiskFileItemFactory();
    ServletFileUpload upload=new ServletFileUpload(factory);
    String to=null;
    InputStream fileStream=null;
    try {
      upload.setFileSizeMax(50 * 1024 * 1024);
      List items=upload.parseRequest(request);
      Iterator iterator=items.iterator();
      while (iterator.hasNext()) {
        FileItem item=(FileItem)iterator.next();
        String name=item.getFieldName();
        InputStream stream=item.getInputStream();
        if (item.isFormField()) {
          if (name.equals("String_Node_Str")) {
            to=Streams.asString(stream);
          }
        }
 else         if (name.equals("String_Node_Str")) {
          fileStream=stream;
        }
      }
      if (to == null || fileStream == null) {
        throw new RuntimeException("String_Node_Str");
      }
      File file=new File(to);
      if (file.isDirectory()) {
        throw new IllegalArgumentException("String_Node_Str" + to + "String_Node_Str");
      }
      if (file.exists()) {
        if (!file.delete() || !file.createNewFile()) {
          throw new Exception("String_Node_Str");
        }
      }
 else       if (!file.getParentFile().exists() && !file.getParentFile().mkdirs() || !file.createNewFile()) {
        throw new Exception("String_Node_Str");
      }
      if (!file.canWrite()) {
        throw new Exception("String_Node_Str");
      }
      OutputStream dst=new FileOutputStream(file);
      Streams.copy(fileStream,dst,true);
      response.getWriter().write("String_Node_Str");
    }
 catch (    Exception e) {
      System.out.print(e.getMessage());
      response.getWriter().write("String_Node_Str");
      throw new ServletException(e.getMessage(),e);
    }
  }
}