evm: roll back CommitStateDB after failing to execute handler (#677)

* Roll back CommitStateDB after failing to execute handler in evm module

* add function CopyCommitStateDB

* add comment

* add comment

* Add ut about the dirty data generated by CommitStateDB

* format code

x/evm/handler.go

@@ -14,16 +14,50 @@ import (
 
 // NewHandler returns a handler for Ethermint type messages.
 func NewHandler(k *Keeper) sdk.Handler {
-	return func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+	return func(ctx sdk.Context, msg sdk.Msg) (result *sdk.Result, err error) {
+		snapshotStateDB := k.CommitStateDB.Copy()
+
+		// The "recover" code here is used to solve the problem of dirty data
+		// in CommitStateDB due to insufficient gas.
+
+		// The following is a detailed description:
+		// If the gas is insufficient during the execution of the "handler",
+		// panic will be thrown from the function "ConsumeGas" and finally
+		// caught by the function "runTx" from Cosmos. The function "runTx"
+		// will think that the execution of Msg has failed and the modified
+		// data in the Store will not take effect.
+
+		// Stacktrace：runTx->runMsgs->handler->...->gaskv.Store.Set->ConsumeGas
+
+		// The problem is that when the modified data in the Store does not take
+		// effect, the data in the modified CommitStateDB is not rolled back,
+		// they take effect, and dirty data is generated.
+		// Therefore, the code here specifically deals with this situation.
+		// See https://github.com/cosmos/ethermint/issues/668 for more information.
+		defer func() {
+			if r := recover(); r != nil {
+				// We first used "k.CommitStateDB = snapshotStateDB" to roll back
+				// CommitStateDB, but this can only change the CommitStateDB in the
+				// current Keeper object, but the Keeper object will be destroyed
+				// soon, it is not a global variable, so the content pointed to by
+				// the CommitStateDB pointer can be modified to take effect.
+				types.CopyCommitStateDB(snapshotStateDB, k.CommitStateDB)
+				panic(r)
+			}
+		}()
 		ctx = ctx.WithEventManager(sdk.NewEventManager())
 		switch msg := msg.(type) {
 		case types.MsgEthereumTx:
-			return handleMsgEthereumTx(ctx, k, msg)
+			result, err = handleMsgEthereumTx(ctx, k, msg)
 		case types.MsgEthermint:
-			return handleMsgEthermint(ctx, k, msg)
+			result, err = handleMsgEthermint(ctx, k, msg)
 		default:
 			return nil, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "unrecognized %s message type: %T", ModuleName, msg)
 		}
+		if err != nil {
+			types.CopyCommitStateDB(snapshotStateDB, k.CommitStateDB)
+		}
+		return result, err
 	}
 }
 

x/evm/handler_test.go

@@ -2,6 +2,7 @@ package evm_test
 
 import (
 	"crypto/ecdsa"
+	"encoding/json"
 	"fmt"
 	"math/big"
 	"strings"
@@ -415,3 +416,112 @@ func (suite *EvmTestSuite) TestSendTransaction() {
 	suite.Require().NoError(err)
 	suite.Require().NotNil(result)
 }
+
+func (suite *EvmTestSuite) TestOutOfGasWhenDeployContract() {
+	// Test contract:
+	//http://remix.ethereum.org/#optimize=false&evmVersion=istanbul&version=soljson-v0.5.15+commit.6a57276f.js
+	//2_Owner.sol
+	//
+	//pragma solidity >=0.4.22 <0.7.0;
+	//
+	///**
+	// * @title Owner
+	// * @dev Set & change owner
+	// */
+	//contract Owner {
+	//
+	//	address private owner;
+	//
+	//	// event for EVM logging
+	//	event OwnerSet(address indexed oldOwner, address indexed newOwner);
+	//
+	//	// modifier to check if caller is owner
+	//	modifier isOwner() {
+	//	// If the first argument of 'require' evaluates to 'false', execution terminates and all
+	//	// changes to the state and to Ether balances are reverted.
+	//	// This used to consume all gas in old EVM versions, but not anymore.
+	//	// It is often a good idea to use 'require' to check if functions are called correctly.
+	//	// As a second argument, you can also provide an explanation about what went wrong.
+	//	require(msg.sender == owner, "Caller is not owner");
+	//	_;
+	//}
+	//
+	//	/**
+	//	 * @dev Set contract deployer as owner
+	//	 */
+	//	constructor() public {
+	//	owner = msg.sender; // 'msg.sender' is sender of current call, contract deployer for a constructor
+	//	emit OwnerSet(address(0), owner);
+	//}
+	//
+	//	/**
+	//	 * @dev Change owner
+	//	 * @param newOwner address of new owner
+	//	 */
+	//	function changeOwner(address newOwner) public isOwner {
+	//	emit OwnerSet(owner, newOwner);
+	//	owner = newOwner;
+	//}
+	//
+	//	/**
+	//	 * @dev Return owner address
+	//	 * @return address of owner
+	//	 */
+	//	function getOwner() external view returns (address) {
+	//	return owner;
+	//}
+	//}
+
+	// Deploy contract - Owner.sol
+	gasLimit := uint64(1)
+	suite.ctx = suite.ctx.WithGasMeter(sdk.NewGasMeter(gasLimit))
+	gasPrice := big.NewInt(10000)
+
+	priv, err := ethsecp256k1.GenerateKey()
+	suite.Require().NoError(err, "failed to create key")
+
+	bytecode := common.FromHex("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")
+	tx := types.NewMsgEthereumTx(1, nil, big.NewInt(0), gasLimit, gasPrice, bytecode)
+	tx.Sign(big.NewInt(3), priv.ToECDSA())
+	suite.Require().NoError(err)
+
+	snapshotCommitStateDBJson, err := json.Marshal(suite.app.EvmKeeper.CommitStateDB)
+	suite.Require().Nil(err)
+
+	defer func() {
+		if r := recover(); r != nil {
+			currentCommitStateDBJson, err := json.Marshal(suite.app.EvmKeeper.CommitStateDB)
+			suite.Require().Nil(err)
+			suite.Require().Equal(snapshotCommitStateDBJson, currentCommitStateDBJson)
+		} else {
+			suite.Require().Fail("panic did not happen")
+		}
+	}()
+
+	suite.handler(suite.ctx, tx)
+	suite.Require().Fail("panic did not happen")
+}
+
+func (suite *EvmTestSuite) TestErrorWhenDeployContract() {
+	gasLimit := uint64(1000000)
+	gasPrice := big.NewInt(10000)
+
+	priv, err := ethsecp256k1.GenerateKey()
+	suite.Require().NoError(err, "failed to create key")
+
+	bytecode := common.FromHex("0xa6f9dae10000000000000000000000006a82e4a67715c8412a9114fbd2cbaefbc8181424")
+
+	tx := types.NewMsgEthereumTx(1, nil, big.NewInt(0), gasLimit, gasPrice, bytecode)
+	tx.Sign(big.NewInt(3), priv.ToECDSA())
+	suite.Require().NoError(err)
+
+	snapshotCommitStateDBJson, err := json.Marshal(suite.app.EvmKeeper.CommitStateDB)
+	suite.Require().Nil(err)
+
+	_, sdkErr := suite.handler(suite.ctx, tx)
+	suite.Require().NotNil(sdkErr)
+
+	currentCommitStateDBJson, err := json.Marshal(suite.app.EvmKeeper.CommitStateDB)
+	suite.Require().Nil(err)
+	suite.Require().Equal(snapshotCommitStateDBJson, currentCommitStateDBJson)
+}

x/evm/types/statedb.go

@@ -760,59 +760,63 @@ func (csdb *CommitStateDB) CreateAccount(addr ethcmn.Address) {
 //
 // NOTE: Snapshots of the copied state cannot be applied to the copy.
 func (csdb *CommitStateDB) Copy() *CommitStateDB {
-	csdb.lock.Lock()
-	defer csdb.lock.Unlock()
 
 	// copy all the basic fields, initialize the memory ones
-	state := &CommitStateDB{
+	state := &CommitStateDB{}
-		ctx:                  csdb.ctx,
+	CopyCommitStateDB(csdb, state)
-		storeKey:             csdb.storeKey,
+
-		paramSpace:           csdb.paramSpace,
+	return state
-		accountKeeper:        csdb.accountKeeper,
+}
-		stateObjects:         []stateEntry{},
+
-		addressToObjectIndex: make(map[ethcmn.Address]int),
+func CopyCommitStateDB(from, to *CommitStateDB) {
-		stateObjectsDirty:    make(map[ethcmn.Address]struct{}),
+	from.lock.Lock()
-		refund:               csdb.refund,
+	defer from.lock.Unlock()
-		logSize:              csdb.logSize,
+
-		preimages:            make([]preimageEntry, len(csdb.preimages)),
+	to.ctx = from.ctx
-		hashToPreimageIndex:  make(map[ethcmn.Hash]int, len(csdb.hashToPreimageIndex)),
+	to.storeKey = from.storeKey
-		journal:              newJournal(),
+	to.paramSpace = from.paramSpace
-	}
+	to.accountKeeper = from.accountKeeper
+	to.stateObjects = []stateEntry{}
+	to.addressToObjectIndex = make(map[ethcmn.Address]int)
+	to.stateObjectsDirty = make(map[ethcmn.Address]struct{})
+	to.refund = from.refund
+	to.logSize = from.logSize
+	to.preimages = make([]preimageEntry, len(from.preimages))
+	to.hashToPreimageIndex = make(map[ethcmn.Hash]int, len(from.hashToPreimageIndex))
+	to.journal = newJournal()
 
 	// copy the dirty states, logs, and preimages
-	for _, dirty := range csdb.journal.dirties {
+	for _, dirty := range from.journal.dirties {
 		// There is a case where an object is in the journal but not in the
 		// stateObjects: OOG after touch on ripeMD prior to Byzantium. Thus, we
 		// need to check for nil.
 		//
 		// Ref: https://github.com/ethereum/go-ethereum/pull/16485#issuecomment-380438527
-		if idx, exist := csdb.addressToObjectIndex[dirty.address]; exist {
+		if idx, exist := from.addressToObjectIndex[dirty.address]; exist {
-			state.stateObjects = append(state.stateObjects, stateEntry{
+			to.stateObjects = append(to.stateObjects, stateEntry{
 				address:     dirty.address,
-				stateObject: csdb.stateObjects[idx].stateObject.deepCopy(state),
+				stateObject: from.stateObjects[idx].stateObject.deepCopy(to),
 			})
-			state.addressToObjectIndex[dirty.address] = len(state.stateObjects) - 1
+			to.addressToObjectIndex[dirty.address] = len(to.stateObjects) - 1
-			state.stateObjectsDirty[dirty.address] = struct{}{}
+			to.stateObjectsDirty[dirty.address] = struct{}{}
 		}
 	}
 
 	// Above, we don't copy the actual journal. This means that if the copy is
 	// copied, the loop above will be a no-op, since the copy's journal is empty.
 	// Thus, here we iterate over stateObjects, to enable copies of copies.
-	for addr := range csdb.stateObjectsDirty {
+	for addr := range from.stateObjectsDirty {
-		if idx, exist := state.addressToObjectIndex[addr]; !exist {
+		if idx, exist := to.addressToObjectIndex[addr]; !exist {
-			state.setStateObject(csdb.stateObjects[idx].stateObject.deepCopy(state))
+			to.setStateObject(from.stateObjects[idx].stateObject.deepCopy(to))
-			state.stateObjectsDirty[addr] = struct{}{}
+			to.stateObjectsDirty[addr] = struct{}{}
 		}
 	}
 
 	// copy pre-images
-	for i, preimageEntry := range csdb.preimages {
+	for i, preimageEntry := range from.preimages {
-		state.preimages[i] = preimageEntry
+		to.preimages[i] = preimageEntry
-		state.hashToPreimageIndex[preimageEntry.hash] = i
+		to.hashToPreimageIndex[preimageEntry.hash] = i
 	}
-
-	return state
 }
 
 // ForEachStorage iterates over each storage items, all invoke the provided