reto seguridad smart contract

reto.sol

//SPDX-License-Identifier:  MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/math/SafeMath.sol";

contract Desafio is Ownable {

    using SafeMath for uint256;
   
    mapping(address => uint) balances;

    function min(uint amount) public isOwner {
        balances[msg.sender] += amount;
    }

    function depositar() public payable{
        balances[msg.sender] += msg.value;
    }

    function retirar() public {
        require(balances[msg.sender] > 0, "Insufficient balance");
        balances[msg.sender] = 0; 
        (bool success, ) = payable(msg.sender).call{value:balances[msg.sender], gas:1000000}(""); 
        require(success, "Error al enviar eth");

    }
}