Redaction: Undo the extra gas check

mediumRecon Audits

Impact

This check:

https://github.com/subvisual/orki/blob/0e5f372d6bd37e794700e46b7be4974d7787319a/contracts/src/PriceFeeds/MainnetPriceFeedBase.sol#L109

solidity📋
 if (uint256(gasleft()) + uint256(2000) <= gasBefore / 64) revert InsufficientGasForExternalCall();

Is meant to ensure that sufficient gas was provided before the revert

Its original version

solidity📋
if (uint256(gasleft()) <= gasBefore / 64) revert InsufficientGasForExternalCall();

Is incorrect as it is ignoring the gas that is necessary

In the case of an oracle reverting due to consuming too much gas this will cause a revert

The check:

solidity📋
 if (uint256(gasleft()) + uint256(2000) <= gasBefore / 64) revert InsufficientGasForExternalCall();

Will not, but this seems to open up to being able to actually triggering a shutdown

This requires very specific gas requirements I did not fully test

But given the fact that the other code is being reviewed by hundreds of auditors, and the POC below, I believe the change should be undone

Mitigation

Revert back to

solidity📋
if (uint256(gasleft()) <= gasBefore / 64) revert InsufficientGasForExternalCall();

I believe the only safe way to check that sufficient gas was provided is to check before the calls, with an hardcoded value