fix: support 4byteTracer for tracer

CHANGELOG.md

@@ -39,6 +39,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (evm) [#725](https://github.com/crypto-org-chain/ethermint/pull/725) feat(RPC): add authorizationList from eth_getTransactionByHash response for EIP-7702 transactions
 * (evm) [#740](https://github.com/crypto-org-chain/ethermint/pull/740) fix: missing tx context during vm initialisation
+* (evm) [#742](https://github.com/crypto-org-chain/ethermint/pull/742) fix: prevent nil pointer dereference in tracer hooks
 
 ## [v0.22.0] - 2025-08-12
 

tests/integration_tests/hardhat/contracts/TestBlockTxProperties.sol

@@ -2,6 +2,20 @@
 pragma solidity ^0.8.0;
 
 contract TestBlockTxProperties {
+    event TxDetailsEvent(
+        address indexed origin,
+        address indexed sender,
+        uint value,
+        bytes data,
+        uint gas,
+        uint gasprice,
+        bytes4 sig
+    );
+
+    function emitTxDetails() public payable {
+        emit TxDetailsEvent(tx.origin, msg.sender, msg.value, msg.data, gasleft(), tx.gasprice, msg.sig);
+    }
+
     function getBlockHash(uint256 blockNumber) public view returns (bytes32) {
         return blockhash(blockNumber);
     }

tests/integration_tests/test_block.py

@@ -1,6 +1,7 @@
+from eth_utils.crypto import keccak
 from web3 import Web3
 
-from .utils import CONTRACTS, deploy_contract, w3_wait_for_new_blocks
+from .utils import ADDRS, CONTRACTS, deploy_contract, w3_wait_for_new_blocks
 
 
 def test_call(ethermint):
@@ -11,3 +12,25 @@ def test_call(ethermint):
     res = Web3.to_hex(contract.caller.getBlockHash(height))
     blk = w3.eth.get_block(height)
     assert res == Web3.to_hex(blk.hash), res
+
+
+def test_block_tx_properties(ethermint):
+    w3 = ethermint.w3
+    contract, _ = deploy_contract(w3, CONTRACTS["TestBlockTxProperties"])
+    acc = ADDRS["community"]
+    gas_price = w3.eth.gas_price
+    tx_hash = contract.functions.emitTxDetails().transact(
+        {"from": acc, "gas": 200000, "gasPrice": gas_price}
+    )
+    tx_hash = Web3.to_hex(tx_hash)
+    tx_receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
+    tx_details_event = contract.events.TxDetailsEvent().process_receipt(tx_receipt)
+    assert tx_details_event is not None
+    data = tx_details_event[0]["args"]
+    print("event_data: ", data)
+    assert data["origin"].lower() == acc.lower()
+    assert data["sender"].lower() == acc.lower()
+    assert data["value"] == 0
+    expected_sig = keccak(b"emitTxDetails()")[:4]
+    assert data["sig"] == data["data"] == expected_sig
+    assert data["gasprice"] == gas_price

tests/integration_tests/test_tracers.py

@@ -14,6 +14,7 @@
     EXPECTED_STRUCT_TRACER,
 )
 from .utils import (
+    ACCOUNTS,
     ADDRS,
     CONTRACTS,
     create_contract_transaction,
@@ -754,3 +755,100 @@ def process(w3):
         assert isinstance(res[0], exceptions.ContractLogicError)
         assert isinstance(res[-1], exceptions.ContractLogicError)
         assert str(res[0]) == str(res[-1]) == "('execution reverted', '0x')"
+
+
+def test_4byte_tracer_intrinsic_gas_too_low(ethermint, geth):
+    method = "debug_traceCall"
+    tracer = {"tracer": "4byteTracer"}
+    acc = derive_new_account(6)
+
+    tx = {
+        "from": ACCOUNTS["community"].address,
+        "to": acc.address,
+        "gas": "0x4e29",
+    }
+
+    def process(w3):
+        tx_res = w3.provider.make_request(method, [tx, "latest", tracer])
+        return json.dumps(tx_res["error"], sort_keys=True)
+
+    providers = [ethermint.w3, geth.w3]
+    with ThreadPoolExecutor(len(providers)) as exec:
+        tasks = [exec.submit(process, w3) for w3 in providers]
+        res = [future.result() for future in as_completed(tasks)]
+        assert len(res) == len(providers)
+        res = [json.loads(r) for r in res]
+        assert res[0]["code"] == res[-1]["code"] == -32000
+        assert "intrinsic gas too low" in res[0]["message"]
+        assert "intrinsic gas too low" in res[-1]["message"]
+
+
+def test_4byte_tracer_success(ethermint, geth):
+    method = "debug_traceCall"
+    tracer = {"tracer": "4byteTracer"}
+    acc = derive_new_account(6)
+
+    tx = {
+        "from": ACCOUNTS["community"].address,
+        "to": acc.address,
+        "gas": hex(21000),
+    }
+
+    def process(w3):
+        tx_res = w3.provider.make_request(method, [tx, "latest", tracer])
+        return json.dumps(tx_res["result"], sort_keys=True)
+
+    providers = [ethermint.w3, geth.w3]
+    with ThreadPoolExecutor(len(providers)) as exec:
+        tasks = [exec.submit(process, w3) for w3 in providers]
+        res = [future.result() for future in as_completed(tasks)]
+        assert len(res) == len(providers)
+        assert res[0] == res[-1]
+
+
+def test_prestate_tracer_block_miner_address(ethermint, geth):
+    """
+    prestateTracer on a tx will include the block miner address
+    """
+    acc = ACCOUNTS["community"]
+    receiver = derive_new_account(12)
+
+    def process(w3):
+        assert (
+            w3.eth.get_balance(receiver.address) == 0
+        ), "receiver balance need to be 0"
+        tx = {
+            "from": acc.address,
+            "to": receiver.address,
+            "value": 1,
+        }
+        receipt = send_transaction(w3, tx, key=acc.key)
+        tx_hash = Web3.to_hex(receipt["transactionHash"])
+        tracer = {"tracer": "prestateTracer"}
+        tx_res = w3.provider.make_request("debug_traceTransaction", [tx_hash, tracer])
+        latest_block = w3.eth.get_block(receipt.blockNumber)
+        block_miner = latest_block.miner
+        return [json.dumps(tx_res["result"], sort_keys=True), block_miner]
+
+    providers = [ethermint.w3, geth.w3]
+    with ThreadPoolExecutor(len(providers)) as exec:
+        tasks = [exec.submit(process, w3) for w3 in providers]
+        res = [future.result() for future in as_completed(tasks)]
+        miner_lhs = res[0][1].lower()
+        miner_rhs = res[1][1].lower()
+        assert len(res) == len(providers)
+
+        from_addr = acc.address.lower()
+        to_addr = receiver.address.lower()
+
+        lhs = json.loads(res[0][0])
+        rhs = json.loads(res[1][0])
+
+        assert len(lhs) == len(rhs) == 3, (lhs, rhs)
+
+        assert lhs[from_addr] is not None
+        assert lhs[to_addr] is not None
+        assert rhs[from_addr] is not None
+        assert rhs[to_addr] is not None
+        assert lhs[miner_lhs] is not None
+        assert rhs[miner_rhs] is not None

x/evm/keeper/state_transition.go

@@ -362,20 +362,24 @@ func (k *Keeper) ApplyMessageWithConfig(
 			tracer.OnGasChange(0, msg.GasLimit, tracing.GasChangeTxInitialBalance)
 		}
 
-		tracer.OnTxStart(
-			evm.GetVMContext(),
-			ethtypes.NewTx(&ethtypes.LegacyTx{
-				To:    msg.To,
-				Data:  msg.Data,
-				Value: msg.Value,
-				Gas:   msg.GasLimit,
-			}),
-			msg.From,
-		)
+		if tracer.OnTxStart != nil {
+			tracer.OnTxStart(
+				evm.GetVMContext(),
+				ethtypes.NewTx(&ethtypes.LegacyTx{
+					To:    msg.To,
+					Data:  msg.Data,
+					Value: msg.Value,
+					Gas:   msg.GasLimit,
+				}),
+				msg.From,
+			)
+		}
 
 		defer func() {
 			debugFn()
-			tracer.OnTxEnd(&ethtypes.Receipt{GasUsed: gasUsed}, err)
+			if tracer.OnTxEnd != nil {
+				tracer.OnTxEnd(&ethtypes.Receipt{GasUsed: gasUsed}, err)
+			}
 		}()
 
 		if cfg.DebugTrace {