Last Man Standing
First Flight #45
Beginner FriendlyFoundrySolidity
100 EXP
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Submission Details
Severity: medium
Valid

Game cannot be played because of wrong require statement

kennisnutz2

Root + Impact

Description

  • normally the claim throne function is surposed to add a new player as the current king. meaning that it should ensure that the player calling claimThrone function is not the current king of the game.

  • The issue here is that instead of requiring that the message sender in not the the current king, it requires that the message sender is the current king, so since the initial current king is the zero address, the function will always fail this check and revert, making the game unplayable.

require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim.");
​

Risk

Likelihood:

  • This issue occurs when anyone calls the claimThrone function to play the game


Impact:

  • claimThrone function always reverts

  • Game cannot be played

Proof of Concept

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
​
import {Test, console2} from "forge-std/Test.sol";
import {Game} from "../src/Game.sol";
​
contract GameTest is Test {
Game public game;
​
address public deployer;
address public player1;
address public player2;
address public player3;
address public maliciousActor;
​
// Initial game parameters for testing
uint256 public constant INITIAL_CLAIM_FEE = 0.1 ether; // 0.1 ETH
uint256 public constant GRACE_PERIOD = 1 days; // 1 day in seconds
uint256 public constant FEE_INCREASE_PERCENTAGE = 10; // 10%
uint256 public constant PLATFORM_FEE_PERCENTAGE = 5; // 5%
​
function setUp() public {
deployer = makeAddr("deployer");
player1 = makeAddr("player1");
player2 = makeAddr("player2");
player3 = makeAddr("player3");
maliciousActor = makeAddr("maliciousActor");
​
vm.deal(deployer, 10 ether);
vm.deal(player1, 10 ether);
vm.deal(player2, 10 ether);
vm.deal(player3, 10 ether);
vm.deal(maliciousActor, 10 ether);
​
vm.startPrank(deployer);
game = new Game(
INITIAL_CLAIM_FEE,
GRACE_PERIOD,
FEE_INCREASE_PERCENTAGE,
PLATFORM_FEE_PERCENTAGE
);
vm.stopPrank();
}
​
function testConstructor_RevertInvalidGracePeriod() public {
vm.expectRevert("Game: Grace period must be greater than zero.");
new Game(INITIAL_CLAIM_FEE, 0, FEE_INCREASE_PERCENTAGE, PLATFORM_FEE_PERCENTAGE);
}
function test__ClaimThrone() public {
vm.startPrank(player1);
vm.expectRevert("Game: You are already the king. No need to re-claim.");
game.claimThrone{value: INITIAL_CLAIM_FEE}();
vm.stopPrank();
}
}

Recommended Mitigation

- require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim.");
​
+ require(msg.sender != currentKing, "Game: You are already the king. No need to re-claim.");
​
Updates

Appeal created

inallhonesty Lead Judge about 1 month ago
Submission Judgement Published
Validated
Assigned finding tags:

Game::claimThrone `msg.sender == currentKing` check is busted

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