WordPress Post Password in URL

function try_auto_login() {
	if (!isset($_GET['pw']))return;
  global $wp_hasher;
  if ( empty( $wp_hasher ) ) {
    require_once( ABSPATH . 'wp-includes/class-phpass.php' );
    $wp_hasher = new PasswordHash(8, true);
  }

  setcookie( 'wp-postpass_' . COOKIEHASH, $wp_hasher->HashPassword( stripslashes( $_GET['pw'] ) ), 0, COOKIEPATH );

  wp_redirect( "/" );exit();
}
add_action('template_redirect','try_auto_login');