Sonic Gateway security record

The `verifyUpdate()` function, found in both `SFCUpdateVerifier` and `ValidatorsRegistry`, contains the following line of code: `require(weight > totalWeight() / 3 * 2, "Insufficient signatures weight");` As Solidity only supports integer division, the result of `totalWeight / 3` will be floored prior to being multiplied by 2. There can be slight inaccuracies in this calculation is a 2 / 3 validator weight is trying to be achieved.

The following require statement is included to ensure that once a fast lane reward is deposited, there isn't another one deposited until the first is consumed. `require(address(this).balance == msg.value, "Fast lane busy");` This is found in `payFastLane()` a `payable` function, which is intended to be the only entry point for ETH in the contract. However, if a savvy user wanted to disrupt calls to this function, they can do so by forcing ETH into the balance of this contract. Although, there is no real incentive for anyone to do this, as they will be wasting their own money, and ultimately contributing to the fast lane reward, for free. Further, after the first call to `update()` this deposit would be consumed.