The withdrawPredictionFees calculate the amount of ETH to withdraw inside the function:
This function will work correctly if it is call before others Players call withdraw function after the end of the tournament.
If not, the fee to withdraw may become a negative number and cause arithmetic underflow everytime the Organiser call this function.
function test_underflowInWithdrawPredictionFees() public {
address stranger2 = makeAddr("stranger2");
address stranger3 = makeAddr("stranger3");
vm.startPrank(stranger);
vm.deal(stranger, 1 ether);
thePredicter.register{value: 0.04 ether}();
vm.stopPrank();
vm.startPrank(stranger2);
vm.deal(stranger2, 1 ether);
thePredicter.register{value: 0.04 ether}();
vm.stopPrank();
vm.startPrank(stranger3);
vm.deal(stranger3, 1 ether);
thePredicter.register{value: 0.04 ether}();
vm.stopPrank();
vm.startPrank(organizer);
thePredicter.approvePlayer(stranger);
thePredicter.approvePlayer(stranger2);
thePredicter.approvePlayer(stranger3);
vm.stopPrank();
vm.startPrank(stranger);
thePredicter.makePrediction{value: 0.0001 ether}(1, ScoreBoard.Result.First);
thePredicter.makePrediction{value: 0.0001 ether}(2, ScoreBoard.Result.Draw);
thePredicter.makePrediction{value: 0.0001 ether}(3, ScoreBoard.Result.First);
vm.stopPrank();
vm.startPrank(stranger2);
thePredicter.makePrediction{value: 0.0001 ether}(1, ScoreBoard.Result.Draw);
thePredicter.makePrediction{value: 0.0001 ether}(2, ScoreBoard.Result.First);
thePredicter.makePrediction{value: 0.0001 ether}(3, ScoreBoard.Result.First);
vm.stopPrank();
vm.startPrank(stranger3);
thePredicter.makePrediction{value: 0.0001 ether}(1, ScoreBoard.Result.First);
thePredicter.makePrediction{value: 0.0001 ether}(2, ScoreBoard.Result.First);
thePredicter.makePrediction{value: 0.0001 ether}(3, ScoreBoard.Result.First);
vm.stopPrank();
vm.startPrank(organizer);
scoreBoard.setResult(0, ScoreBoard.Result.First);
scoreBoard.setResult(1, ScoreBoard.Result.First);
scoreBoard.setResult(2, ScoreBoard.Result.First);
scoreBoard.setResult(3, ScoreBoard.Result.First);
scoreBoard.setResult(4, ScoreBoard.Result.First);
scoreBoard.setResult(5, ScoreBoard.Result.First);
scoreBoard.setResult(6, ScoreBoard.Result.First);
scoreBoard.setResult(7, ScoreBoard.Result.First);
scoreBoard.setResult(8, ScoreBoard.Result.First);
vm.stopPrank();
vm.startPrank(stranger);
thePredicter.withdraw();
vm.stopPrank();
vm.startPrank(organizer);
thePredicter.withdrawPredictionFees();
vm.stopPrank();
assertEq(address(thePredicter).balance, 0 ether);
}
contract ThePredicter {
+ uint256 public predictionFeeToWithdraw;
.
.
.
function makePrediction(uint256 matchNumber, ScoreBoard.Result prediction) public payable {
.
.
.
+ predictionFeeToWithdraw += predictionFee;
}
function withdrawPredictionFees() public {
if (msg.sender != organizer) {
revert ThePredicter__NotEligibleForWithdraw();
}
- uint256 fees = address(this).balance - players.length * entranceFee;
- (bool success,) = msg.sender.call{value: fees}("");
+ (bool success,) = msg.sender.call{value: predictionFeeToWithdraw}("");
require(success, "Failed to withdraw");
}
