Liquid Staking

Summary

For upgradeable contracts, there must be storage gap to "allow developers to freely add new state variables in the future without compromising the storage compatibility with existing deployments" (quote OpenZeppelin). Otherwise it may be very difficult to write new implementation code. Without storage gap, the variable in child contract might be overwritten by the upgraded base contract if new variables are added to the base contract. This could have unintended and very serious consequences to the child contracts, potentially causing loss of user fund or cause the contract to malfunction completely.

Vulnerability Details

https://github.com/Cyfrin/2024-09-stakelink/blob/main/contracts/core/priorityPool/PriorityPool.sol#L4

import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/token/ERC20/utils/SafeERC20Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/utils/cryptography/MerkleProofUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/utils/math/MathUpgradeable.sol";

https://github.com/Cyfrin/2024-09-stakelink/blob/main/contracts/core/priorityPool/WithdrawalPool.sol#L4

import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/token/ERC20/utils/SafeERC20Upgradeable.sol";

Impact

Tools Used

Recommendations

uint256[50] private __gap;