Hawk High
First Flight #39
Beginner FriendlySolidity
100 EXP
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Submission Details
Severity: medium
Valid

Storage layout not compatible between LevelOne and LevelTwo

mihaihng

Summary

Global variables in LevelTwo are declared in a different order than in LevelOne.


schoolFees - not present anymore

mappings reviewCount, lastReviewTime - not present anymore

Results a shift in storage slot numbers.

Vulnerability Details

The proxy’s storage will no longer map correctly to the expected locations.

Impact

Undefined behavior and contract breakage.

Can cause loss of data/funds, calling functions with wrong data, security issues and incapacity to use the contract.

Tools Used

Manual Code Review

Recommendations

Refactor LevelTwo to match LevelOne.
Ensure that all variables from LevelOne are declared at the very top level of LevelTwo, followed only by new ones.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.26;
​
import {Initializable} from "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
​
contract LevelTwo is Initializable {
using SafeERC20 for IERC20;
​
////////////////////////////////
///// VARIABLES /////
////////////////////////////////
address principal;
bool inSession;
uint256 schoolFees; // Missing
uint256 public immutable reviewTime = 1 weeks;
uint256 public sessionEnd;
uint256 public bursary;
uint256 public cutOffScore;
mapping(address => bool) public isTeacher;
mapping(address => bool) public isStudent;
mapping(address => uint256) public studentScore;
mapping(address => uint256) private reviewCount; // Missing
mapping(address => uint256) private lastReviewTime; // Missing
address[] listOfStudents;
address[] listOfTeachers;
​
uint256 public constant TEACHER_WAGE_L2 = 40;
uint256 public constant PRINCIPAL_WAGE_L2 = 5;
uint256 public constant PRECISION = 100;
​
IERC20 public usdc;
​
// Rest of the cod



Updates

Lead Judging Commences

yeahchibyke Lead Judge 2 months ago
Submission Judgement Published
Validated
Assigned finding tags:

storage collision

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