Livepeer contest - Tomio's results

Handle

Tomio

Vulnerability details

Impact

expensive gas

Proof of Concept

https://github.com/livepeer/arbitrum-lpt-bridge/blob/main/contracts/L1/gateway/L1LPTGateway.sol#L227

Tools Used

Remix

Recommended Mitigation Steps

change to bytes memory emptyBytes;

Handle

Tomio

Vulnerability details

Impact

save in memory can save more gas instead of double storage call

Proof of Concept

https://github.com/livepeer/arbitrum-lpt-bridge/blob/ebf68d11879c2798c5ec0735411b08d0bea4f287/contracts/L2/gateway/L2LPTDataCache.sol#L57

Tools Used

Remix

Recommended Mitigation Steps

add l2SupplyFromL1 to memory example:

        uint256 savel2SupplyFromL1 = l2SupplyFromL1;
        if (_amount > savel2SupplyFromL1) {
            savel2SupplyFromL1 = 0;
        } else {
            savel2SupplyFromL1 -= _amount;
        }

Handle

Tomio

Vulnerability details

Impact

Expensive gas

Proof of Concept

https://github.com/livepeer/protocol/blob/20e7ebb86cdb4fe9285bf5fea02eb603e5d48805/contracts/token/BridgeMinter.sol#L90

Tools Used

Remix

Recommended Mitigation Steps

call balance instead of address(this).balance can save gas

function withdrawETHToL1Migrator() external onlyL1Migrator returns (uint256) {
        uint256 balance = address(this).balance;

        // call() should be safe from re-entrancy here because the L1Migrator and l1MigratorAddr are trusted
        (bool ok, ) = l1MigratorAddr.call.value(balance)("");
        require(ok, "BridgeMinter#withdrawETHToL1Migrator: FAIL_CALL");

        return balance;
    }