address-sanitizer

address-sanitizer is a skill for Claude Code from marduk191/qwen3_mcp. It costs 35 tokens per session (2,772 once invoked), scanned A, a copy of address-sanitizer, MIT.

A testing tool that adds checks for illegal memory use while C and C++ programs run. It can detect problems such as buffer overflows, use-after-free errors, double frees, and memory leaks.

In plain words
What is it for?
Use it when fuzzing C or C++ code, investigating memory-related crashes, or testing unsafe parts of Rust code.
Why use it?
It exposes memory bugs during fuzzing or tests, including bugs that may otherwise appear only as unexplained crashes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the testing-handbook-skills plugin — 15 skills shipped together

Good fit Use it when fuzzing C or C++ code, investigating memory-related crashes, or testing unsafe parts of Rust code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/marduk191/qwen3_mcp/address-sanitizer
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add marduk191/qwen3_mcp --skill address-sanitizer
Clone the repo
git clone --depth 1 https://github.com/marduk191/qwen3_mcp

Made for: Claude Code.

Or install testing-handbook-skills, the plugin that ships this one along with the rest of its 15 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for address-sanitizer

README.md
[![agentmods](https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/address-sanitizer/github.svg)](https://agentmods.dev/skills/marduk191/qwen3_mcp/address-sanitizer)
Your own site
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/address-sanitizer"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/address-sanitizer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for address-sanitizer

Your own site · 80×15
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/address-sanitizer"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/address-sanitizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,772 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 95% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00035 $0.02772
Opus 5 $0.00017 $0.01386
Sonnet 5 $0.00007 $0.00554
Haiku 4.5 $0.00003 $0.00277

Measured 12d ago against content hash 5404e7352610, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

address-sanitizer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

95% identical to address-sanitizer — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/testing-handbook-skills/skills/address-sanitizer/SKILL.md · 342 lines

How it starts

The opening of the file, as written. The whole thing — 342 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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 suspected

Skip this technique when:

  • Running production code (ASan can reduce security)
  • Platform is Windows or macOS (limited ASan support)
  • Performance overhead is unacceptable for your use case
  • Fuzzing pure safe languages without FFI (e.g., pure Go, pure Java)

Quick Reference

Task Command/Pattern
Enable ASan (Clang/GCC) -fsanitize=address
Enable verbosity ASAN_OPTIONS=verbosity=1
Disable leak detection ASAN_OPTIONS=detect_leaks=0
Force abort on error ASAN_OPTIONS=abort_on_error=1
Multiple options ASAN_OPTIONS=verbosity=1:abort_on_error=1

Step-by-Step

Step 1: Compile with ASan

Compile and link your code with the -fsanitize=address flag:

clang -fsanitize=address -g -o my_program my_program.c

Read the full file on GitHub · 342 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 342 lines · 35 tokens per session scan A 5404e7352610

Subscribe to this mod's changes

address-sanitizer is a skill published in the GitHub repository marduk191/qwen3_mcp (13 stars, last pushed 7mo ago), licensed MIT. It adds 35 tokens to every session and 2,772 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to address-sanitizer, differing in 5 lines, and is treated as a copy.

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