First Flight #2: Puppy Raffle

Summary

uint256 to uint64 conversion can cause overflow

Vulnerability Details

totalFees = totalFees + uint64(fee);
In this calculation, fee is cast to uint64, but fee is originally uint256. when a number larger than the range that can be represented by uint64 is entered, it causes an overflow and the calculation goes wrong

Impact

WithdrawFees() cannot be invoked because the balance of the Fee is collapsed, and it may not be possible to withdraw the Fee

Tools Used

Manual

Recommendations

Use the safecast library