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Codeup::claimCodeupERC20() may be forever DoSed by creating the Uniswap pool before it is called

Crit/HighCODEUP·Three Sigma · DeFi game · 23rd October, 2024H-4

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Description

Uniswap pools may be created without the underlying tokens existence, which means that someone may do this before Codeup::claimCodeupERC20() is ever called, making it revert when UniswapV2Factory::createPair() is called as the pool has already been created.

Recommendation

UniswapV2Router::addLiquidity() creates the pool if it does not yet exist, so there is not need to directly created it. The only concern is setting the uniswapV2Pool variable, which may be performed for example by doing:

solidity
if (uniswapV2Pool == address(0)) {
    uint256 maxFirstLiquidity = MAX_FIRST_LIQUIDITY_AMOUNT;
    uint256 firstLiquidity = wethBalance > maxFirstLiquidity
        ? maxFirstLiquidity
        : wethBalance;

    _addLiquidity(
        routerMemory,
        wethMemory,
        codeupERC20Memory,
        firstLiquidity,
        FIRST_LIQUIDITY_GAME_TOKEN,
        0,
        0,
        currentContract
    );
    
    uniswapV2Pool = IUniswapV2Factory(uniswapV2Factory).getPair(
        wethMemory,
        codeupERC20Memory
    );

    emit PoolCreated(uniswapV2Pool);
} else {