v4 Hook Pre-Deployment Audit Checklist

v4 Hook Pre-Deployment Audit Checklist

Comprehensive checklist for auditing Uniswap v4 hooks before deployment.

1. Access Control

1.1 PoolManager Verification

• All hook callbacks verify msg.sender == address(poolManager)
• Verification uses modifier or explicit check at function start
• No code paths bypass the verification

1.2 Router Authorization

• Router allowlisting implemented if hook restricts callers
• Allowlist modifications are admin-protected
• Cannot add zero address to allowlist

1.3 Admin Functions

• Admin role transfer is two-step (propose/accept) or timelock-protected
• Critical admin functions have event emissions
• Admin cannot brick the contract (e.g., renounce without safeguards)

2. Delta Accounting

2.1 Balance Invariants

• All returned deltas are backed by actual token movements
• take() calls match returned delta values
• settle() calls properly account for received tokens
• Invariant: sum(all deltas) == 0 for every transaction

2.2 Token Handling

• Fee-on-transfer tokens handled (measure actual received amounts)
• Rebasing tokens handled or explicitly blocked
• ERC-777 reentrancy considered
• Token decimals not assumed (queried from token)

2.3 Settlement Flow

• Correct order: sync() -> transfer() -> settle()
• No partial settlements left hanging
• Error handling doesn't leave accounting in bad state

3. Permissions Review

3.1 Enabled Permissions Audit

For each enabled permission, document:

3.2 Delta Return Permissions (Critical Review)

If any delta return permission is enabled:

• NoOp attack vector analyzed and mitigated
• All code paths returning non-zero deltas reviewed
• Deltas are always backed by liquidity provision
• Multiple independent reviewers have verified

4. Reentrancy Protection

4.1 External Calls

• All external calls identified and documented
• Reentrancy guards applied where needed
• State changes follow checks-effects-interactions pattern
• No callbacks to untrusted contracts

4.2 Token Callbacks

• ERC-777 tokensReceived hook considered
• ERC-721/1155 callbacks considered if applicable
• Flash loan callbacks considered

5. Gas and DoS

5.1 Loop Bounds

• All loops have maximum iteration limits
• Limits are appropriate for block gas limit
• User-controllable arrays bounded

5.2 Gas Estimation

• Gas usage tested for worst-case scenarios
• No operations that could exceed block gas limit
• External call gas limits are reasonable

5.3 DoS Vectors

• No unbounded array iterations
• No unbounded mapping iterations
• Failed external calls don't block hook functionality
• Griefing attacks considered

6. Input Validation

6.1 Parameter Validation

• All external inputs validated
• hookData properly decoded and validated
• No assumptions about parameter ranges
• Overflow/underflow protection (Solidity 0.8.x or SafeMath)

6.2 Pool Key Validation

• Hook is authorized for the pool
• Currency addresses validated
• Fee tier validated if relevant

7. State Management

7.1 Storage

• No sensitive data stored on-chain
• Storage slots don't collide (if using assembly)
• Transient storage used appropriately
• Storage variables initialized correctly

7.2 State Transitions

• All state transitions have valid preconditions
• No invalid intermediate states possible
• State can be recovered from errors

8. Upgrade Safety (if applicable)

8.1 Proxy Patterns

• Upgrade mechanism is access-controlled
• Timelock or governance required for upgrades
• Storage layout documented
• Upgrade path tested

8.2 Migration Safety

• Old state can be migrated to new implementation
• No loss of funds during migration
• Rollback plan exists

9. Testing Requirements

9.1 Unit Tests

• Every public/external function tested
• Every require/revert condition tested
• Edge cases tested (zero amounts, max values, etc.)
• All code paths covered

9.2 Fuzz Testing

• Foundry fuzz tests for all state-changing functions
• Minimum 10,000 fuzz runs
• Custom fuzz invariants defined
• No failures in extended fuzzing

9.3 Invariant Testing

• Core invariants defined and tested
• Delta accounting invariants tested
• Balance invariants tested
• Access control invariants tested

9.4 Integration Testing

• Fork tests against mainnet state
• Tests with real pool addresses
• Tests with various token types
• End-to-end swap flow tested

10. Static Analysis

10.1 Automated Tools

• Slither analysis completed (all findings addressed)
• Mythril analysis completed
• Solhint linting passed
• Custom detectors for v4-specific issues

10.2 Manual Review

• Line-by-line code review completed
• Business logic reviewed against specification
• Comparison with similar audited hooks

11. Documentation

11.1 Code Documentation

• NatSpec comments for all public functions
• Complex logic explained in comments
• Assumptions documented

11.2 External Documentation

• Architecture diagram
• Threat model document
• Deployment procedure
• Emergency procedures

12. Deployment Preparation

12.1 Pre-Deployment

• Hook address mined with correct permission bits
• Constructor parameters verified
• Deployment script reviewed and tested
• Gas estimation for deployment

12.2 Post-Deployment

• Verify source code on block explorer
• Verify permissions match expected
• Test transaction on mainnet
• Monitoring and alerting configured

Audit Sign-Off

Risk Assessment Summary

Findings Log

Audit Tier Guidelines

Based on risk assessment, determine required audit level:

Tier 1: Self-Audit (Risk Score 0-5)

• Internal code review
• Full test coverage
• Static analysis tools

Tier 2: Peer Audit (Risk Score 6-12)

• Tier 1 requirements
• External developer review
• Extended fuzz testing

Tier 3: Professional Audit (Risk Score 13-20)

• Tier 2 requirements
• Audit by security firm
• Bug bounty program

Tier 4: Multi-Audit (Risk Score 21+)

• Tier 3 requirements
• Multiple independent audits
• Formal verification considered
• Extended bug bounty with significant rewards