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Submission Details
Severity: low
Invalid

Hardcoded Chainlink Price Feed Decimals

Summary

The _check function in the contract assumes that Chainlink price feeds always have 8 decimals, which is incorrect. This can lead to incorrect price scaling and potential mispricing issues for assets where the Chainlink oracle uses a different decimal format.

Vulnerability Details

Chainlink price decimal is assumed to be always 8 which is not always true. More so, even if it were 8 for the relevant tokens used in the protocol, there is no guarantee it will remain the same.

function _check(address token, uint256 price) internal view {
// https://github.com/code-423n4/2021-06-tracer-findings/issues/145
(, int chainLinkPrice, , uint256 updatedAt, ) = AggregatorV2V3Interface(dataFeed[token]).latestRoundData();
require(updatedAt > block.timestamp - maxTimeWindow[token], "stale price feed");
uint256 decimals = 30 - IERC20Meta(token).decimals();
@> price = price / 10 ** (decimals - 8); // Chainlink price decimals is always 8.
require(
_absDiff(price, chainLinkPrice.toUint256()) * BPS / chainLinkPrice.toUint256() < priceDiffThreshold[token],
"price offset too big"
);
}

Impact

The contract may miscalculate price differences.

Tools Used

Manual Review

Recommendations

add the loc: uint256 chainlinkDecimals = AggregatorV2V3Interface(dataFeed[token]).decimals(); to the _check() function.

function _check(address token, uint256 price) internal view {
// https://github.com/code-423n4/2021-06-tracer-findings/issues/145
(, int chainLinkPrice, , uint256 updatedAt, ) = AggregatorV2V3Interface(dataFeed[token]).latestRoundData();
require(updatedAt > block.timestamp - maxTimeWindow[token], "stale price feed");
uint256 decimals = 30 - IERC20Meta(token).decimals();
+ uint256 chainlinkDecimals = AggregatorV2V3Interface(dataFeed[token]).decimals();
- price = price / 10 ** (decimals - 8); // Chainlink price decimals is always 8.
+ price = price / 10 ** (decimals - chainlinkDecimals);
require(
_absDiff(price, chainLinkPrice.toUint256()) * BPS / chainLinkPrice.toUint256() < priceDiffThreshold[token],
"price offset too big"
);
}
Updates

Lead Judging Commences

n0kto Lead Judge 9 months ago
Submission Judgement Published
Invalidated
Reason: Out of scope
Assigned finding tags:

Admin is trusted / Malicious keepers

Please read the CodeHawks documentation to know which submissions are valid. If you disagree, provide a coded PoC and explain the real likelihood and the detailed impact on the mainnet without any supposition (if, it could, etc) to prove your point. Keepers are added by the admin, there is no "malicious keeper" and if there is a problem in those keepers, that's out of scope. ReadMe and known issues states: " * System relies heavily on keeper for executing trades * Single keeper point of failure if not properly distributed * Malicious keeper could potentially front-run or delay transactions * Assume that Keeper will always have enough gas to execute transactions. There is a pay execution fee function, but the assumption should be that there's more than enough gas to cover transaction failures, retries, etc * There are two spot swap functionalies: (1) using GMX swap and (2) using Paraswap. We can assume that any swap failure will be retried until success. " " * Heavy dependency on GMX protocol functioning correctly * Owner can update GMX-related addresses * Changes in GMX protocol could impact system operations * We can assume that the GMX keeper won't misbehave, delay, or go offline. " "Issues related to GMX Keepers being DOS'd or losing functionality would be considered invalid."

Suppositions

There is no real proof, concrete root cause, specific impact, or enough details in those submissions. Examples include: "It could happen" without specifying when, "If this impossible case happens," "Unexpected behavior," etc. Make a Proof of Concept (PoC) using external functions and realistic parameters. Do not test only the internal function where you think you found something.

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