First Flight #2: Puppy Raffle

Summary

Using nested for loops inside a function can cause DOS attack in the function which may result is the revert of the function due to using too much gas.

Vulnerability Details

##POC

    function enterRaffle(address[] memory newPlayers) public payable {
    require(msg.value == entranceFee * newPlayers.length, "PuppyRaffle: Must send enough to enter raffle");
    
    for (uint256 i = 0; i < newPlayers.length; i++) {
        players.push(newPlayers[i]);
    }
      // @audit-issue : can cause dos.
    // Check for duplicates
    for (uint256 i = 0; i < players.length - 1; i++) {
        for (uint256 j = i + 1; j < players.length; j++) {
            require(players[i] != players[j], "PuppyRaffle: Duplicate player");
        }
    }
    emit RaffleEnter(newPlayers);
}

Test Case

   function testCanEnterRaffleMany1() public {
    address[] memory players = new address[]((2**256)/2);
    for(uint256 i=0;i<(2**256)/2;i++)
    {    
        players[i]=address(i);
     }
    puppyRaffle.enterRaffle{value: entranceFee * (2**256-1)/2}(players);
    for(uint256 i=0;i<(2**256)/2;i++)
    {
    assertEq(puppyRaffle.players(i), address(i));
    }
} 

##Result

     Failing tests:
     Encountered 1 failing test in test/PuppyRaffleTest.t.sol:PuppyRaffleTest
     [FAIL. Reason: EvmError: Revert] testCanEnterRaffleMany1() (gas: 267)

     Encountered a total of 1 failing tests

Impact

The function can revert.

Tools Used

Foundry

Recommendations

Avoid using nested for loops in the function.