fix(evm): Fix unit inconsistency related to AuthInfo.Fee and txData.Fee

[Unique-Divine]

Purpose / Abstract

• Meant to close https://github.com/code-423n4/2024-11-nibiru-findings/issues/44
• Part of [evm] Audit tracking ticket - Jan 2025 #2155

fix(evm): Fix unit inconsistency related to AuthInfo.Fee and txData.Fee by using effective fee. Prior to this change, there were two areas where a wei amount was passed as an argument to a "Cosmos" fee where it expects units of unibi (micronibi).

Since txData.Fee does not take into account the fact that the network has a global and absolute minimum gas price of 1 unibi == 10^{12} wei, this is fixed by using txData.EffectiveFeeWei, as the latter function guarantees the minimum gas price without adding configuration on the part of end-users. This is similar to what we do to compute weiPerGas in EthereumTx:

	weiPerGas := txMsg.EffectiveGasPriceWeiPerGas(evmConfig.BaseFeeWei)

Summary by CodeRabbit

• Bug Fixes

  • Resolved unit inconsistency in transaction fees for Nibiru EVM
  • Improved fee computation logic to ensure correct effective fee calculation
  • Enforced minimum gas price of 1 unibi in transaction processing

• Documentation

  • Updated changelog to reflect recent EVM-related fixes
  • Enhanced code comments for fee calculation methods

[coderabbitai]

Walkthrough

This pull request addresses a unit inconsistency in transaction fee calculations within the Nibiru EVM. The changes modify how transaction fees are computed across multiple files, introducing an effective fee calculation that enforces a minimum gas price of 1 unibi. The modifications ensure more consistent and accurate fee handling in Ethereum-compatible transactions, focusing on aligning AuthInfo.Fee and txData.Fee to prevent potential discrepancies in fee processing.

Changes

File	Change Summary
CHANGELOG.md	Added entry for fee unit inconsistency fix
app/evmante/evmante_validate_basic.go	Updated fee computation logic to use effectiveFeeMicronibi
x/evm/msg.go	Modified BuildTx method to compute effective fee with minimum 1 unibi gas price

Sequence Diagram

sequenceDiagram
    participant TX as Ethereum Transaction
    participant Validator as EVM Ante Handler
    participant FeeCalc as Fee Calculator
    
    TX->>Validator: Submit Transaction
    Validator->>FeeCalc: Calculate Effective Fee
    FeeCalc-->>Validator: Compute Fee (Min 1 unibi)
    Validator->>TX: Validate and Process Transaction

Loading

Possibly related PRs

• fix(evm): Fix unit inconsistency related to AuthInfo.Fee and txData.Fee  #2157 - Direct relation to fee unit inconsistency fix
• fix(evm): proper nonce management in statedb #2130 - Nonce management in statedb
• fix(evm): erc20 born funtoken: properly burn bank coins after convert… #2139 - Burning bank coins after conversion
• fix(precompile): consume gas before returning error #2152 - Gas consumption in precompile calls
• fix(evm): JSON encoding for the EIP55Addr struct was not following the Go conventions and needed to include double quotes around the hexadecimal string. #2154 - JSON encoding fix for EIP55Addr struct

Suggested reviewers

• k-yang

Poem

🐰 Hopping through code with glee,
Fees now dance in harmony!
One unibi, minimum and bright,
Transactions flow with pure delight
A rabbit's fix, precise and neat! 🚀

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between da4c2c7 and 1e9ef8a.

📒 Files selected for processing (3)

• CHANGELOG.md (1 hunks)
• app/evmante/evmante_validate_basic.go (1 hunks)
• x/evm/msg.go (2 hunks)

🔇 Additional comments (3)

x/evm/msg.go (1)

Line range hint 348-370: LGTM! Fee computation now correctly enforces minimum gas price.

The changes properly handle the unit conversion from wei to micronibi (unibi) using the effective fee calculation, which ensures the minimum gas price of 1 unibi is respected.

Let's verify that all fee calculations are consistent by checking other fee-related code:

✅ Verification successful

Fee calculations are consistent across the codebase

The fee handling implementation maintains consistency throughout:

• Base fee is properly defined as 1 micronibi (unibi)
• All fee calculations correctly use EffectiveFeeWei with proper unit conversion
• The changes integrate well with both EVM and Cosmos-SDK fee mechanisms

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Search for fee-related calculations to ensure consistency
rg -A 3 "Fee|fee|EffectiveFee" 

Length of output: 71175

app/evmante/evmante_validate_basic.go (1)

125-130: LGTM! Consistent fee handling with msg.go changes.

The fee computation changes in the ante handler correctly mirror the approach used in BuildTx, ensuring consistent minimum gas price enforcement across the system.

CHANGELOG.md (1)

76-76: LGTM! Clear and descriptive changelog entry.

The changelog entry properly documents the fix for the fee unit inconsistency issue and its resolution using effective fee calculations.

Finishing Touches

• 📝 Generate Docstrings (Beta)

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.20%. Comparing base (5533a2a) to head (1e9ef8a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2157   +/-   ##
=======================================
  Coverage   65.19%   65.20%           
=======================================
  Files         277      277           
  Lines       22240    22242    +2     
=======================================
+ Hits        14500    14502    +2     
  Misses       6746     6746           
  Partials      994      994           

Files with missing lines	Coverage Δ
app/evmante/evmante_validate_basic.go	86.23% <100.00%> (+0.12%)	⬆️
x/evm/msg.go	62.38% <100.00%> (+0.11%)	⬆️