Delvir0 - Chainlink lastestRoundData is not checked for stale or round completeness

[sherlock-admin]

Delvir0

medium

Chainlink lastestRoundData is not checked for stale or round completeness

Summary

It currently has no checks at all

Vulnerability Detail

latestRoundData returns: (uint80 roundID, int256 price, uint256 startedAt, uint256 timeStamp, uint80 answeredInRound).
In order to ensure Chainlink returned the correct price, these needs to be checked.

Impact

Not checking returned values can result in wrong price calculations of getPriceUSD.

Code Snippet

https://github.com/sherlock-audit/2023-05-USSD/blob/main/ussd-contracts/contracts/oracles/StableOracleDAI.sol#L48

Tool used

Manual Review

Recommendation

Implement the following solution:
sherlock-audit/2023-02-blueberry-judging#94

Duplicate of #31