FreeGuard: A Faster Secure Heap Allocator

TL;DR

FreeGuard is a secure heap allocator that offers strong protection against heap-related attacks with minimal performance overhead, matching the speed of default Linux allocators.

Contribution

It introduces a new secure heap allocator that balances security and performance, addressing scalability issues of previous secure allocators.

Findings

Less than 2% performance overhead on average

Effective in defending against various heap-related attacks

Addresses scalability issues of existing secure allocators

Abstract

In spite of years of improvements to software security, heap-related attacks still remain a severe threat. One reason is that many existing memory allocators fall short in a variety of aspects. For instance, performance-oriented allocators are designed with very limited countermeasures against attacks, but secure allocators generally suffer from significant performance overhead, e.g., running up to 10x slower. This paper, therefore, introduces FreeGuard, a secure memory allocator that prevents or reduces a wide range of heap-related attacks, such as heap overflows, heap over-reads, use-after-frees, as well as double and invalid frees. FreeGuard has similar performance to the default Linux allocator, with less than 2% overhead on average, but provides significant improvement to security guarantees. FreeGuard also addresses multiple implementation issues of existing secure allocators, such as the issue of scalability. Experimental results demonstrate that FreeGuard is very effective in defending against a variety of heap-related attacks.