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[XiaoHai67890]

Ethernaut Vulnerability Fix PR

漏洞描述

原关卡合约存在重入攻击漏洞，攻击者可以在 withdraw 调用中再次调用自身函数，从而重复提取资金。

修复方案

• 添加 noReentrant 修饰器，防止在函数执行中再次进入。
• 先更新状态再发送以太币，符合 Checks-Effects-Interactions 模式。

部署

npm install
npx hardhat compile
npx hardhat test

[github-actions]

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