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evm: roll back CommitStateDB after failing to execute handler (#677)
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* 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
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@summerpro
summerpro authored Jan 8, 2021
1 parent ed313c9 commit 153478e
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Showing 3 changed files with 182 additions and 34 deletions.
40 changes: 37 additions & 3 deletions x/evm/handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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
}
}

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110 changes: 110 additions & 0 deletions x/evm/handler_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package evm_test

import (
"crypto/ecdsa"
"encoding/json"
"fmt"
"math/big"
"strings"
Expand Down Expand Up @@ -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)
}
66 changes: 35 additions & 31 deletions x/evm/types/statedb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -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{
ctx: csdb.ctx,
storeKey: csdb.storeKey,
paramSpace: csdb.paramSpace,
accountKeeper: csdb.accountKeeper,
stateObjects: []stateEntry{},
addressToObjectIndex: make(map[ethcmn.Address]int),
stateObjectsDirty: make(map[ethcmn.Address]struct{}),
refund: csdb.refund,
logSize: csdb.logSize,
preimages: make([]preimageEntry, len(csdb.preimages)),
hashToPreimageIndex: make(map[ethcmn.Hash]int, len(csdb.hashToPreimageIndex)),
journal: newJournal(),
}
state := &CommitStateDB{}
CopyCommitStateDB(csdb, state)

return state
}

func CopyCommitStateDB(from, to *CommitStateDB) {
from.lock.Lock()
defer from.lock.Unlock()

to.ctx = from.ctx
to.storeKey = from.storeKey
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 {
state.stateObjects = append(state.stateObjects, stateEntry{
if idx, exist := from.addressToObjectIndex[dirty.address]; exist {
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
state.stateObjectsDirty[dirty.address] = struct{}{}
to.addressToObjectIndex[dirty.address] = len(to.stateObjects) - 1
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 {
if idx, exist := state.addressToObjectIndex[addr]; !exist {
state.setStateObject(csdb.stateObjects[idx].stateObject.deepCopy(state))
state.stateObjectsDirty[addr] = struct{}{}
for addr := range from.stateObjectsDirty {
if idx, exist := to.addressToObjectIndex[addr]; !exist {
to.setStateObject(from.stateObjects[idx].stateObject.deepCopy(to))
to.stateObjectsDirty[addr] = struct{}{}
}
}

// copy pre-images
for i, preimageEntry := range csdb.preimages {
state.preimages[i] = preimageEntry
state.hashToPreimageIndex[preimageEntry.hash] = i
for i, preimageEntry := range from.preimages {
to.preimages[i] = preimageEntry
to.hashToPreimageIndex[preimageEntry.hash] = i
}

return state
}

// ForEachStorage iterates over each storage items, all invoke the provided
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