Sommelier A-12

Security Audit

October 27, 2023

Version 1.0.0

Presented by 0xMacro

Table of Contents

Introduction

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.

Overall Assessment

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.

Specification

Our understanding of the specification was based on the following sources:

Trust Model, Assumptions, and Accepted Risks (TMAAR)

Trusted entities:

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.

Assumptions:

Accepted Risks:

Source Code

The following source code was reviewed during the audit:

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 postion using the CellarAdaptor.

Contract SHA256
src/modules/adaptors/Aura/AuraERC4626Adaptor.sol

06476b6468024206eeec29752f0ba4b6fa1ac72b0a3aba811c38c27fdde6bc82

src/modules/price-router/Extensions/Redstone/RedstoneEthPriceFeedExtension.sol

0968c0307e35690b26dea9586313349a78a16a4528212cb2a2a828c0f2deeaa6

src/modules/price-router/Extensions/Curve/CurveEMAExtension.sol

beeb61fd5a2715912f77d80b97192b2075dc84eec8e461acf889a16ae2eff69c

src/modules/adaptors/Frax/CollateralFTokenAdaptor.sol

25b8314ebfd899449ec4f5b08535d08307494aaa1058e63112d4a7258ff025f0

src/modules/adaptors/Frax/CollateralFTokenAdaptorV1.sol

c4f9e9a1f768e3074a5dbc8b8f37bb3ae1389d6331dccb7e8f6d06b53ce6a38d

src/modules/adaptors/Frax/DebtFTokenAdaptor.sol

61fe645c1b296b781246c5864a08f74337ff9d5fc95501de9c8fd9689e8fc953

src/modules/adaptors/Frax/DebtFTokenAdaptorV1.sol

e702784c116a8d5cf1460e1e38ca00c34656ca02768dcadb52ecd068cc1b7133

src/modules/adaptors/Frax/FTokenAdaptor.sol

94c03365dfa57e6f9a6f377e2eb94d34c7132e961a8f563b840cfbe64138bf09

src/modules/adaptors/Frax/FTokenAdaptorV1.sol

c3a2638038d5526d13882288c69a0e56ddc4292026348ab952d11b9d7f09895f

src/base/ERC4626SharePriceOracle.sol

998cc4bd75ed70f6c6fd15b6fc33ec50547dc26435d54ff0fcdec9486fb730cd

src/modules/adaptors/ERC4626Adaptor.sol

3675d603b20d0c6bc7a76d0b822badda437616d9d3b9a1df341ef612c82da2fe

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.

Issue Descriptions and Recommendations

Click on an issue to jump to it, or scroll down to see them all.

Security Level Reference

We quantify issues in three parts:

  1. The high/medium/low/spec-breaking impact of the issue:
    • How bad things can get (for a vulnerability)
    • The significance of an improvement (for a code quality issue)
    • The amount of gas saved (for a gas optimization)
  2. The high/medium/low likelihood of the issue:
    • How likely is the issue to occur (for a vulnerability)
  3. The overall critical/high/medium/low severity of the issue.

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.

Issue Details

M-1

Incorrect price calculation for CurveEmaExtension

Topic
Protocol Design
Status
Impact
Medium
Likelihood
Medium

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.

M-2

Share Price Oracles may not be properly initialized

Topic
Error Recovery
Status
Impact
Medium
Likelihood
Low

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.

L-1

Identifiers not updated for Frax Lend adaptors

Topic
Protocol Design
Status
Impact
Low
Likelihood
High

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.

L-2

Missing event when initializing share price oracle

Topic
Events
Status
Impact
Low
Likelihood
Medium

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.

Disclaimer

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.