address-sanitizer

SKILL.md

Memory error detection for C/C++ fuzzing via compile-time instrumentation.

Detects buffer overflows, use-after-free, double-free, and memory leaks by instrumenting code at compile time with the -fsanitize=address flag

Requires approximately 20TB of virtual memory; disable fuzzer memory limits with -rss_limit_mb=0 (libFuzzer) or -m none (AFL++)

Introduces 2–4x performance overhead; best suited for testing and fuzzing, not production use

Integrates with libFuzzer, AFL++, cargo-fuzz, and honggfuzz; configure via ASAN_OPTIONS environment variable for verbosity, leak detection, and error handling behavior

AddressSanitizer (ASan)

AddressSanitizer (ASan) is a widely adopted memory error detection tool used extensively during software testing, particularly fuzzing. It helps detect memory corruption bugs that might otherwise go unnoticed, such as buffer overflows, use-after-free errors, and other memory safety violations.

Overview

ASan is a standard practice in fuzzing due to its effectiveness in identifying memory vulnerabilities. It instruments code at compile time to track memory allocations and accesses, detecting illegal operations at runtime.

Key Concepts

Concept
Description

Instrumentation
ASan adds runtime checks to memory operations during compilation

Shadow Memory
Maps 20TB of virtual memory to track allocation state

Performance Cost
Approximately 2-4x slowdown compared to non-instrumented code

Detection Scope
Finds buffer overflows, use-after-free, double-free, and memory leaks

When to Apply