First Flight #2: Puppy Raffle

Summary

The function enterRaffle() checks for the duplicate entrants with for loop.

Vulnerability Details

The for loop used increases the gas the gas cost every time the loop runs.
Scenario
1st raffle for 50 players amount of gas used = x
2nd raffle for 50 players amount of gas used >>> x

POC
code ''' /// EnterRaffle ///
/////////////////////
function testGasCost() public {
vm.txGasPrice(2);

   uint256 playersNum = 50;
   address[] memory players = new address[](playersNum);
   for (uint256 i=0; i<playersNum; i++){
    players[i] = address(i);
   }

uint256 gasStart = gasleft();
puppyRaffle.enterRaffle{value: entranceFee*playersNum}(players);
uint256 gasEnd = gasleft();
uint256 gasUsed = (gasStart - gasEnd) * tx.gasprice;
console.log("Gas Cost",gasUsed);

for (uint256 i=0; i<playersNum; i++){
    players[i]=address(i + playersNum);
    }
gasStart = gasleft();
puppyRaffle.enterRaffle{value: entranceFee*playersNum}(players);
gasEnd = gasleft();
uint256 gasUsedAgain = (gasStart - gasEnd) * tx.gasprice;
console.log("Gas Cost 2nd time",gasUsedAgain);

assert(gasUsed < gasUsedAgain);
}

'''

Impact

It will be impossible for the players to enter the raffle with the increased gas cost.

Tools Used

Manual Review

Recommendations

It is recommended not to use for loops.