First Flight #2: Puppy Raffle

Summary

the totalFunds variable does not handle overflow. Any solidity versions < 0.8 do not throw any errors for overflows/underflows so funds would be lost.

Vulnerability Details

Overflow will happen when the value is too large to be stored in the uint64 data type, usually in solidity versions < 0.8 it will be caused to wrap around (which is the case here).

Impact

Can lead to a loss of funds and potentially unexpected behaviour within your smart contract.

Tools Used

Manual Review

Recommendations

Change the variable to a uint256 data type and also use OpenZeppelins safeMath library to prevent overflow/underflow because of the version of solidity you are using (for the version of solidity your using it is actually referred to as SafeCast).