The following document
\documentclass{book}
\usepackage{bookman}
\usepackage{tocbibind}
\makeindex
\begin{document}
\tableofcontents
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\chapter{Lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\section{lorem ipsum}
\end{document}
produces the following pdf

How can I fix the overlap?