Security Audit
October 27, 2023
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Sommelier's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team from October 24, 2023 to October 26, 2023.
The purpose of this audit is to review the source code of certain Sommelier Solidity contracts, and provide feedback on the design, architecture, and quality of the source code with an emphasis on validating the correctness and security of the software in its entirety.
Disclaimer: While Macro’s review is comprehensive and has surfaced some changes that should be made to the source code, this audit should not solely be relied upon for security, as no single audit is guaranteed to catch all possible bugs.
The following is an aggregation of issues found by the Macro Audit team:
Severity | Count | Acknowledged | Won't Do | Addressed |
---|---|---|---|---|
Medium | 2 | - | - | 2 |
Low | 2 | - | - | 2 |
Sommelier was quick to respond to these issues.
Our understanding of the specification was based on the following sources:
The goal of the system is to to have checks and balances for each permissioned action, where if any one permissioned entity acts malicious, the others can remedy the situation, requiring multiple points failure before it can negatively impact users.
The following source code was reviewed during the audit:
4faacd442fefe1d4d2b39182ad7ed2bc67786d6b
4ee541dfd3b494c7eaabd047c73750242f27fe09
Specifically, we audited the following contracts within this repository for the initial part of the audit, additionally sFrax was evaluated to ensure it would work as intended as a position using the CellarAdaptor.
Contract | SHA256 |
---|---|
src/modules/adaptors/Aura/AuraERC4626Adaptor.sol |
|
src/modules/price-router/Extensions/Redstone/RedstoneEthPriceFeedExtension.sol |
|
src/modules/price-router/Extensions/Curve/CurveEMAExtension.sol |
|
src/modules/adaptors/Frax/CollateralFTokenAdaptor.sol |
|
src/modules/adaptors/Frax/CollateralFTokenAdaptorV1.sol |
|
src/modules/adaptors/Frax/DebtFTokenAdaptor.sol |
|
src/modules/adaptors/Frax/DebtFTokenAdaptorV1.sol |
|
src/modules/adaptors/Frax/FTokenAdaptor.sol |
|
src/modules/adaptors/Frax/FTokenAdaptorV1.sol |
|
src/base/ERC4626SharePriceOracle.sol |
|
src/modules/adaptors/ERC4626Adaptor.sol |
|
Note: This document contains an audit solely of the Solidity contracts listed above. Specifically, the audit pertains only to the contracts themselves, and does not pertain to any other programs or scripts, including deployment scripts.
Click on an issue to jump to it, or scroll down to see them all.
We quantify issues in three parts:
This third part – the severity level – is a summary of how much consideration the client should give to fixing the issue. We assign severity according to the table of guidelines below:
Severity | Description |
---|---|
(C-x) Critical |
We recommend the client must fix the issue, no matter what, because not fixing would mean significant funds/assets WILL be lost. |
(H-x) High |
We recommend the client must address the issue, no matter what, because not fixing would be very bad, or some funds/assets will be lost, or the code’s behavior is against the provided spec. |
(M-x) Medium |
We recommend the client to seriously consider fixing the issue, as the implications of not fixing the issue are severe enough to impact the project significantly, albiet not in an existential manner. |
(L-x) Low |
The risk is small, unlikely, or may not relevant to the project in a meaningful way. Whether or not the project wants to develop a fix is up to the goals and needs of the project. |
(Q-x) Code Quality |
The issue identified does not pose any obvious risk, but fixing could improve overall code quality, on-chain composability, developer ergonomics, or even certain aspects of protocol design. |
(I-x) Informational |
Warnings and things to keep in mind when operating the protocol. No immediate action required. |
(G-x) Gas Optimizations |
The presented optimization suggestion would save an amount of gas significant enough, in our opinion, to be worth the development cost of implementing it. |
CurveEmaExtension
In CurveEmaExtension.sol
’s getPriceInUSD()
, the price is pulled from the pool in terms of the first asset in the pools coins
array. When the price is converted to USD
, the price’s decimals are assumed to be using the coins0
's decimals.
function getPriceInUSD(ERC20 asset) external view override returns (uint256 price) {
ExtensionStorage memory stor = extensionStorage[asset];
CurvePool pool = CurvePool(stor.pool);
ERC20 coins0 = getCoinsZero(pool);
uint256 priceInAsset = getPriceFromCurvePool(pool, stor.index, stor.needIndex);
uint256 assetPrice = priceRouter.getPriceInUSD(coins0);
price = assetPrice.mulDivDown(priceInAsset, 10 ** coins0.decimals());
}
Reference: CurveEmaExtension.sol#L69-L78
function getPriceFromCurvePool(CurvePool pool, uint8 index, bool needIndex) public view returns (uint256) {
return needIndex ? pool.price_oracle(index) : pool.price_oracle();
}
Reference: CurveEmaExtension.sol#L93-L95
However, the price returned by a curve pool’s price_oracle()
function is not using the base asset’s decimals, since pools using USDT or USDC as their base asset return a price with 18 decimals, when these tokens both have 6 decimals. This can lead to incorrect price values for pools with a base asset that doesn't use 18 decimals.
Remediations to Consider
It seems like all prices returned from a curve pool’s price_oracle()
function uses 18 decimals, so instead of using the base asset’s decimals, 18 could be used instead. Alternatively the price’s decimals could be set as a value in the extensionStorage
struct for each asset.
The ERC4626SharePriceOracle.sol
’s initialize()
function a Chainlink automationForwarder
is setup by registering a upkeep address for the contract by calling registerUpkeep()
on Chainlink’s registrar. It is assumed, however, that an upkeep will be registered when that call is made, but there are cases where registration is not accepted immediately and is set to pending, awaiting approval.
uint256 upkeepId;
if (_shouldAutoApprove(s_triggerRegistrations[params.triggerType], sender)) {
s_triggerRegistrations[params.triggerType].approvedCount++;
upkeepId = _approve(params, hash);
} else {
uint96 newBalance = s_pendingRequests[hash].balance + params.amount;
s_pendingRequests[hash] = PendingRequest({admin: params.adminAddress, balance: newBalance});
}
Reference: AutomationRegistrar2_1.sol#L419-L426
When a registration is set to pending, it will return a value of zero for its upkeepId
and when the forwarder is queried form the registry with that id, the zero address is returned. This means that if the registrar’s upkeep limit has been reached or if automatic upkeep approval is shut off, then share price oracles can not properly set a automationForwarder
, as calls to the registry’s registerUpkeep()
will be set to pending, ending up with automationForwarder
being set to the zero address, and no way of setting it to the proper address once the registration is approved.
Currently the upkeep auto approve limit on mainnet is 500, which can be increased or decreased, but if reached then all new registrations will have to await approval, preventing proper initialization of share price oracles.
Remediations to Consider
Add a function that can only be called if initialize()
was called, but the automationForwarder
address is still not set, and have this function verify a passed in upkeep id to ensure the id corresponds to the upkeep that was registered, then query the automationForwarder
from the registry using that upkeep id. This will allow share price oracles to be setup if their upkeep isn’t immediately approved. Also consider emitting an event if the automationForwarder
isn’t set when initialized.
The code was altered for the DebtFTokenAdaptor
, DebtFTokenAdaptorV1
, CollateralFTokenAdaptor
and the CollateralFTokenAdaptorV1
contracts. In order for these updated adaptors to be added to the registry they need to return a unique value from their identifier()
function to distinguish them from the current Frax Lend adaptors.
/**
* @notice Trust an adaptor to be used by cellars
* @param adaptor address of the adaptor to trust
*/
function trustAdaptor(address adaptor) external onlyOwner {
if (isAdaptorTrusted[adaptor]) revert Registry__AdaptorAlreadyTrusted(adaptor);
bytes32 identifier = BaseAdaptor(adaptor).identifier();
if (isIdentifierUsed[identifier]) revert Registry__IdentifierNotUnique();
isAdaptorTrusted[adaptor] = true;
isIdentifierUsed[identifier] = true;
}
Reference: Registry.sol#L309-L315
However, the identifer()
function has not been updated along with these changes.
Remediations to Consider
Update the version number in each of the updated Frax Lend adaptor’s identifier()
functions to allow them to be added to the registry.
In ERC4626SharePriceOracle.sol
’s initialize()
function, a chainlink upkeep address is registered, and the corresponding automationForwarder
address is set. There is no event emitted for this call, and the generated upkeepId
returned when registering an upkeep is not emitted, and may be useful to know the upkeepId
that corresponds to the share price oracle’s automationForwarder
, as useful data in Chainlink’s registrar and registry is mapped to an upkeepId
.
Remediations to Consider
Add an event that emits the upkeepId
and automationForwarder
address, when initialize()
is called.
Macro makes no warranties, either express, implied, statutory, or otherwise, with respect to the services or deliverables provided in this report, and Macro specifically disclaims all implied warranties of merchantability, fitness for a particular purpose, noninfringement and those arising from a course of dealing, usage or trade with respect thereto, and all such warranties are hereby excluded to the fullest extent permitted by law.
Macro will not be liable for any lost profits, business, contracts, revenue, goodwill, production, anticipated savings, loss of data, or costs of procurement of substitute goods or services or for any claim or demand by any other party. In no event will Macro be liable for consequential, incidental, special, indirect, or exemplary damages arising out of this agreement or any work statement, however caused and (to the fullest extent permitted by law) under any theory of liability (including negligence), even if Macro has been advised of the possibility of such damages.
The scope of this report and review is limited to a review of only the code presented by the Sommelier team and only the source code Macro notes as being within the scope of Macro’s review within this report. This report does not include an audit of the deployment scripts used to deploy the Solidity contracts in the repository corresponding to this audit. Specifically, for the avoidance of doubt, this report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project. In this report you may through hypertext or other computer links, gain access to websites operated by persons other than Macro. Such hyperlinks are provided for your reference and convenience only, and are the exclusive responsibility of such websites’ owners. You agree that Macro is not responsible for the content or operation of such websites, and that Macro shall have no liability to your or any other person or entity for the use of third party websites. Macro assumes no responsibility for the use of third party software and shall have no liability whatsoever to any person or entity for the accuracy or completeness of any outcome generated by such software.