Root + Impact
Description
The `claimThrone()` function contains a faulty check that prevents anyone except the current king from claiming the throne. this is logically incorrect. It only allows the current king to call `claimThrone()`, which breaks the core functionality of the game. According to the intended design, any new player (who is not the current king) should be able to claim the throne by paying the correct fee. Only re-claims by the current king should be disallowed.
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.");
uint256 sentAmount = msg.value;
uint256 previousKingPayout = 0;
uint256 currentPlatformFee = 0;
uint256 amountToPot = 0;
currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
platformFeesBalance = platformFeesBalance + currentPlatformFee;
amountToPot = sentAmount - currentPlatformFee;
pot = pot + amountToPot;
currentKing = msg.sender;
lastClaimTime = block.timestamp;
playerClaimCount[msg.sender] = playerClaimCount[msg.sender] + 1;
totalClaims = totalClaims + 1;
claimFee = claimFee + (claimFee * feeIncreasePercentage) / 100;
emit ThroneClaimed(msg.sender, sentAmount, claimFee, pot, block.timestamp);
}
Risk
Impact:
- Game is Unplayable: No one can ever become king, because no one starts as the king and the contract does not allow non-kings to claim.
- Full funds lock: The pot will remain empty, and the gracePeriod countdown can never begin. - Revenue freeze: No platform fees are collected since no successful claims occur.
- Loss of core functionality: The entire purpose of the "Last Man Standing" game fails.
Proof of Concept
pase the following test fuction in you `Game.t.sol` file
function testClaimThrone_LogicError_BlocksNewPlayers() public {
vm.prank(player1);
vm.expectRevert("Game: You are already the king. No need to re-claim.");
game.claimThrone{value: INITIAL_CLAIM_FEE}();
}
Recommended Mitigation
Update the `Game::claimThrone()` function to use the correct logic that only prevents the current king from reclaiming:
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.");
uint256 sentAmount = msg.value;
uint256 previousKingPayout = 0;
uint256 currentPlatformFee = 0;
uint256 amountToPot = 0;
currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
platformFeesBalance = platformFeesBalance + currentPlatformFee;
amountToPot = sentAmount - currentPlatformFee;
pot = pot + amountToPot;
currentKing = msg.sender;
lastClaimTime = block.timestamp;
playerClaimCount[msg.sender] = playerClaimCount[msg.sender] + 1;
totalClaims = totalClaims + 1;
claimFee = claimFee + (claimFee * feeIncreasePercentage) / 100;
emit ThroneClaimed(msg.sender, sentAmount, claimFee, pot, block.timestamp);
}
