Authorization Attribute call on Index method is causing infinity loop

Question

I am trying to use authorization attribute on index method as shown below but it causes an infinity loop of index method call.

[Authorization]
[HttpGet]
public ActionResult Index()
{
    //here is controller code..
}

Code for Authorization Attribute is as follow.

public class AuthorizationAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        //try
        //{
            if (HttpContext.Current.Session["username"] != null && HttpContext.Current.Session["password"] != null)
            {
                string username = HttpContext.Current.Session["username"].ToString();
                string password = HttpContext.Current.Session["password"].ToString();
                string actionName = filterContext.ActionDescriptor.ActionName;  
                string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
                if (username == null || username == "" || password == null || password == "")
                {
                    filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new
                    {
                        controller = "User",
                        action = "LogOut",
                    }));
                    //base.OnActionExecuting(filterContext);
                }
                else
                {

                    //filterContext.HttpContext.Response.Redirect("~/"+controllerName+"/"+actionName);
                    //return;
                    //filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new
                    //{
                       // controller = controllerName,
                       // action = actionName,
                   // })); ...Removed this redirection and it worked for me.
                    base.OnActionExecuting(filterContext);
                }
            }
            else
            {

                filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new
                {
                    controller = "User",
                    action = "LogOut",
                }));
                //base.OnActionExecuting(filterContext);
            }
            base.OnActionExecuting(filterContext);
        //}
        //catch(Exception ex)
        //{
        //    throw ex;
        //}
       
    }
}

I am trying to use it with session created with user login and without login it redirects to login page but after successfull login when I try to redirect to Index methhod of another controller it causes infinite loop of redirect, giving error in browser "redirected too many times."