Liquidations will be frozen if a token's oracle goes down or chainlink reverts call for any reason

Summary

Hubble only implements chainlink oracles, if any of these oracles goes down or any of the call reverts all liquidations or anything attached to querying chainlink would not possible, potentially DOSing all instances of querying that particular oracle in scope. isn't it reasonable to implement a query to chainlink in a try/catch incase this call is reverted and implement a fallback oracle?

Vulnerability Detail

Chainlink has taken oracles offline in extreme cases, which one could argue is to ensure that it wasn't providing inaccurate data to protocols as at the time they decide to take it down In such a situation everything pertaining a call to chainlink would be inaccessible, i.e liquidations and every other logic where getting the price of a token is needed.

Impact

Normal operation of protocol can not be guaranteed, multiple DOS could be encountered, in the case of liquidations it could even be worse as these may not be possible at a time when the protocol needs them most. Resulting in the value of user's asset falling way below their debts, i.e in the case where oracle is down while the price of the asset is falling, this easily pushes the protocol into insolvency.

Code Snippet

Oracle.sol#L106-L123:


    function getLatestRoundData(AggregatorV3Interface _aggregator)
        internal
        view
        returns (
            uint80,
            uint256 finalPrice,
            uint256
        )
    {
        (uint80 round, int256 latestPrice, , uint256 latestTimestamp, ) = _aggregator.latestRoundData();
        finalPrice = uint256(latestPrice);
        if (latestPrice <= 0) {
            requireEnoughHistory(round);
            (round, finalPrice, latestTimestamp) = getRoundData(_aggregator, round - 1);
        }
        return (round, finalPrice, latestTimestamp);
    }

Tool used

Manual Audit

Recommendation

Provide a safeguard, after discussions with the sponsors the idea of a try/catch was accepted, and then an implementation of a fallback oracle in the case where chainlink is inacessible

sherlock-audit / 2023-04-hubble-exchange-judging

Bauchibred - Liquidations will be frozen if a token's oracle goes down or chainlink reverts call for any reason #245