Buffer Overflow Analysis for C

TL;DR

This paper introduces a formal, stateless approach to analyze buffer overflows in C programs by modeling buffers and null characters, aiming to facilitate automatic analyzer construction without user-written code.

Contribution

It presents a novel stateless formulation for buffer overflow analysis in C, enabling automatic analyzer generation and avoiding complex stateful modeling.

Findings

Feasibility of describing buffer overflow analysis with lattice-valued functions

Development of stateless functions for null position and buffer-pointer mappings

Potential for automatic construction of static analyzers for C programs

Abstract

Buffer overflow detection and mitigation for C programs has been an important concern for a long time. This paper defines a string buffer overflow analysis for C programs. The key ideas of our formulation are (a) separating buffers from the pointers that point to them, (b) modelling buffers in terms of sizes and sets of positions of null characters, and (c) defining stateless functions to compute the sets of null positions and mappings between buffers and pointers. This exercise has been carried out to test the feasibility of describing such an analysis in terms of lattice valued functions and relations to facilitate automatic construction of an analyser without the user having to write C/C++/Java code. This is facilitated by devising stateless formulations because stateful formulations combine features through side effects in states raising a natural requirement of C/C++/Java code to be written to describe them. Given the above motivation, the focus of this paper is not to build good static approximations for buffer overflow analysis but to show how given static approximations could be formalized in terms of stateless formulations so that they become amenable to automatic construction of analysers.