address-sanitizer

npx skills add trailofbits/skills --skill address-sanitizer --agent claude-code

Same command for any agent — swap --agent for codex, cursor, copilot.

# 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 **Apply this technique when:** - Fuzzing C/C++ code for memory safety vulnerabilities - Testing Rust code with unsafe blocks - Debugging crashes related to memory corruption - Running unit tests where memory errors are su

clang -fsanitize=address -g -o my_program my_program.c
export ASAN_OPTIONS=verbosity=1:abort_on_error=1:detect_leaks=0
clang -o fuzz_target fuzz_target.c
clang -fsanitize=address -g -o fuzz_target fuzz_target.c
gcc -o test_suite test_suite.c -lcheck
gcc -fsanitize=address -g -o test_suite test_suite.c -lcheck
clang -fsanitize=address,undefined -g -o fuzz_target fuzz_target.c
afl-fuzz -m none -i input_dir -o output_dir ./fuzz
cargo fuzz run fuzz_target --sanitizer=address
honggfuzz -i input_dir -o output_dir -- ./fuzz_target_asan