fix: ics02 and ics20 gas calculation

[vladjdk]

Replaces zero-valued gas configs with instantiated values in ICS02, and charges for gas in ICS20.

[greptile-apps]

Greptile Summary

This PR fixes zero-gas DoS vulnerabilities in the ICS02 and ICS20 precompiles by ensuring KV store operations are properly metered. The ICS02 constructor now uses storetypes.KVGasConfig() and storetypes.TransientGasConfig() instead of zero-valued structs, and the ICS20 transferWithStateDB no longer overrides the context's gas configs with empty ones mid-call.

• ICS02: Zero-valued GasConfig{} in NewPrecompile caused RequiredGas to return 0 for every call; replaced with the proper SDK defaults so callers are charged based on calldata size.
• ICS20: A block that saved/zeroed/restored KV gas configs inside transferWithStateDB has been removed, meaning IBC transfer execution now charges for KV store reads/writes at the standard rate; the defer-restore was already a no-op (operating on a by-value ctx copy) so no state-restore behavior is lost.
• Tests: A new unit test pins the RequiredGas formula against the SDK KV-cost constants for all ICS02 methods, and the UpdateClient integration test gas limit is bumped to 500,000 to reflect the real cost now charged.

Confidence Score: 5/5

Safe to merge — both changes are straightforward removals of zero-gas overrides, backed by a new unit test and a passing integration test with an updated gas budget.

The ICS02 constructor change is a one-line swap to a well-known SDK helper, and the ICS20 removal eliminates code whose defer-restore was already a no-op. The new unit test explicitly pins the cost formula, and the integration test confirms the real-world gas budget. No new code paths are introduced that could regress unrelated behavior.

No files require special attention.

Important Files Changed

Filename	Overview
precompiles/ics02/ics02.go	Replaces zero-valued GasConfig{} with storetypes.KVGasConfig() and storetypes.TransientGasConfig(), closing a zero-gas DoS bypass where every call was free regardless of calldata size.
precompiles/ics20/tx.go	Removes the block that temporarily zeroed KV gas configs inside transferWithStateDB; KV store operations during ICS20 transfers now charge gas at the standard rate set in the constructor.
precompiles/ics02/ics02_test.go	New unit test guards against regression of the zero-gas DoS bypass; verifies RequiredGas returns non-zero values and matches the SDK KV-cost formula for all ICS02 methods.
evmd/tests/ibc/ics02_precompile_client_test.go	Integration test gas limit for UpdateClient bumped from 200,000 to 500,000 to accommodate the real KV-store gas now charged after the fix.

Sequence Diagram

sequenceDiagram
    participant Caller as EVM Caller
    participant EVM as EVM Engine
    participant PC as Precompile (ICS02/ICS20)
    participant RNA as runNativeAction
    participant KV as KV Store

    Caller->>EVM: call precompile (calldata)
    EVM->>PC: RequiredGas(input)
    Note over PC: KVGasConfig().WriteCostFlat<br/>+ WriteCostPerByte*len(input)<br/>(was 0 before fix)
    PC-->>EVM: base gas charged up front

    EVM->>PC: Run(evm, contract, readonly)
    PC->>RNA: RunNativeAction(action)
    Note over RNA: ctx = ctx.WithKVGasConfig(p.KvGasConfig)<br/>.WithTransientKVGasConfig(p.TransientKVGasConfig)
    RNA->>PC: action(ctx)

    alt ICS02 UpdateClient / VerifyMembership
        PC->>KV: read/write client state
        Note over KV: gas metered at KVGasConfig() rate
    else ICS20 Transfer (after fix)
        PC->>KV: read/write during transfer
        Note over KV: gas metered normally (zero-override block removed)
    end

    KV-->>PC: result
    PC-->>RNA: (bz, err)
    Note over RNA: cost = GasConsumed - initialGas<br/>contract.UseGas(cost)
    RNA-->>EVM: bz
    EVM-->>Caller: result

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_{Reviews (3): Last reviewed commit: "fix tests" | Re-trigger Greptile}

[vladjdk]

@greptile review

[vladjdk]

@greptile review

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.20%. Comparing base (64e859b) to head (472b830).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1164      +/-   ##
==========================================
- Coverage   64.31%   64.20%   -0.12%     
==========================================
  Files         336      336              
  Lines       24054    24063       +9     
==========================================
- Hits        15471    15450      -21     
- Misses       6973     6991      +18     
- Partials     1610     1622      +12     

Files with missing lines	Coverage Δ
precompiles/ics02/ics02.go	84.61% <100.00%> (+3.84%)	⬆️
precompiles/ics20/tx.go	49.62% <ø> (-22.16%)	⬇️

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[mattac21]

should add a changelog entry for this. also do you think we need to note this in the upgrade guide?

[mattac21]

@mergify backport to release/v0.7.x

[mergify]

backport to release/v0.7.x

❌ No backport have been created

Details

• Backport to branch to failed

GitHub error: Branch not found

• #1171 fix: ics02 and ics20 gas calculation (backport #1164) has been created for branch release/v0.7.x