Use `a/b/c` instead of `a/(b*c)` to decrease arithmetic overflow probability.
Summary
getTokenAmountFromUsd() returns (usdAmountInWei * PRECISION) / (uint256(price) * ADDITIONAL_FEED_PRECISION);. This will revert if the denominator (uint256(price) * ADDITIONAL_FEED_PRECISION) exceeds type(uint256).max.
Vulnerability Details
Considering Chainlink TOKEN/USD price feed to have precision of 8 decimals, (uint256(price) * ADDITIONAL_FEED_PRECISION) will exceed type(uint256).max if dollar price of TOKEN is more than 115792089237316195423570985008687907853269984665640564039457 and revert.
To reduce such an occurrence, one can return this instead: (usdAmountInWei * PRECISION) / uint256(price) / ADDITIONAL_FEED_PRECISION;.
Impact
Current syntax causes overflow for very large USD price of a token and always reverts, blocking all liquidation attempts.
Tools Used
Manual review
Recommendations
Use syntax:
(usdAmountInWei * PRECISION) / uint256(price) / ADDITIONAL_FEED_PRECISION;.OR,
return 0;whenpriceexceeds the threshold.
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