Submission Details
Severity:
Incorrect Access Logic in `Game::claimThrone` Prevents Game Initialization
Description
The function currently contains an inverted condition that only allows the current king to claim the throne again, while blocking all other users. Since the currentKing is initially address(0), no real user can satisfy the requirement. As a result, the game cannot start, and no player interaction is possible, rendering the contract unusabl
function claimThrone() external payable gameNotEnded nonReentrant {
require(msg.value >= claimFee, "Game: Insufficient ETH sent to claim the throne.");
@> require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim.");
// @audit No one can Claim Throne
uint256 sentAmount = msg.value;
uint256 previousKingPayout = 0;
uint256 currentPlatformFee = 0;
uint256 amountToPot = 0;
// Calculate platform fee
currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
// Defensive check to ensure platformFee doesn't exceed available amount after previousKingPayout
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
platformFeesBalance = platformFeesBalance + currentPlatformFee;
// Remaining amount goes to the pot
amountToPot = sentAmount - currentPlatformFee;
pot = pot + amountToPot;
// Update game state
currentKing = msg.sender;
lastClaimTime = block.timestamp;
playerClaimCount[msg.sender] = playerClaimCount[msg.sender] + 1;
totalClaims = totalClaims + 1;
// Increase the claim fee for the next player
claimFee = claimFee + (claimFee * feeIncreasePercentage) / 100;
emit ThroneClaimed(
msg.sender,
sentAmount,
claimFee,
pot,
block.timestamp
);
}
Risk
Likelihood:
The issue will occur immediately upon deployment, as the currentKing is initialized to address(0) and no user can match that address
Impact:
The game becomes permanently stuck in an unusable state, preventing any progression or interaction !
Proof of Concept
// SPDX-License-Identifier: MIT
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;
// 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");
vm.deal(deployer, 10 ether);
vm.deal(player1, 10 ether);
vm.startPrank(deployer);
game = new Game(
INITIAL_CLAIM_FEE,
GRACE_PERIOD,
FEE_INCREASE_PERCENTAGE,
PLATFORM_FEE_PERCENTAGE
);
vm.stopPrank();
}
function testClaimThrone() 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();
}
salah@fedora:~/Desktop/2025-07-last-man-standing$ forge test --mt testClaimThrone -vvvv
[⠊] Compiling...
[⠔] Compiling 1 files with Solc 0.8.30
[⠒] Solc 0.8.30 finished in 435.58ms
Compiler run successful!
Ran 1 test for test/Game.t.sol:GameTest
[PASS] testClaimThrone() (gas: 47290)
Traces:
[47290] GameTest::testClaimThrone()
├─ [0] VM::startPrank(player1: [0x7026B763CBE7d4E72049EA67E89326432a50ef84])
│ └─ ← [Return]
├─ [0] VM::expectRevert(custom error 0xf28dceb3: 4Game: You are already the king. No need to re-claim.)
│ └─ ← [Return]
├─ [29259] Game::claimThrone{value: 100000000000000000}()
│ └─ ← [Revert] Game: You are already the king. No need to re-claim.
├─ [0] VM::stopPrank()
│ └─ ← [Return]
└─ ← [Stop]
Suite result: ok. 1 passed; 0 failed; 0 skipped; finished in 1.90ms (160.16µs CPU time)
Ran 1 test suite in 16.14ms (1.90ms CPU time): 1 tests passed, 0 failed, 0 skipped (1 total tests)
Recommended Mitigation
function claimThrone() external payable gameNotEnded nonReentrant {
require(msg.value >= claimFee, "Game: Insufficient ETH sent to claim the throne.");
- 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.");
// @audit No one can Claim Throne
uint256 sentAmount = msg.value;
uint256 previousKingPayout = 0;
uint256 currentPlatformFee = 0;
uint256 amountToPot = 0;
// Calculate platform fee
currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
// Defensive check to ensure platformFee doesn't exceed available amount after previousKingPayout
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
platformFeesBalance = platformFeesBalance + currentPlatformFee;
// Remaining amount goes to the pot
amountToPot = sentAmount - currentPlatformFee;
pot = pot + amountToPot;
// Update game state
currentKing = msg.sender;
lastClaimTime = block.timestamp;
playerClaimCount[msg.sender] = playerClaimCount[msg.sender] + 1;
totalClaims = totalClaims + 1;
// Increase the claim fee for the next player
claimFee = claimFee + (claimFee * feeIncreasePercentage) / 100;
emit ThroneClaimed(
msg.sender,
sentAmount,
claimFee,
pot,
block.timestamp
);
}
Updates
Appeal created
inallhonesty 4 months ago
Submission Judgement Published Assigned finding tags:
Game::claimThrone `msg.sender == currentKing` check is busted
Rewards breakdown
nSLOC
181This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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