Parity-ethereum: VM execution error after upgrading parity version

[Pzixel]

_Before filing a new issue, please provide the following information._

I'm running:

• Which Parity version?: 1.11.8
• Which operating system?: Linux
• How installed?: docker
• Are you fully synchronized?: yes
• Which network are you connected to?: private
• Did you try to restart the node?: yes

I have a contract with migration mechanism that allows to fix bugs without affecting existing clients. The entire contract:

pragma solidity ^0.4.23;

contract SeasonFactory {    
    address[] public seasons;
    address public newVersionAddress;

    function migrateToNewVersion(address newVersionAddress_) public {
        require (newVersionAddress == 0);
        require (newVersionAddress_ != address(this));
        newVersionAddress = newVersionAddress_;
    }

    function addSeason(address season) public {
        if (newVersionAddress != 0) {
            SeasonFactory newVersion = SeasonFactory(newVersionAddress);
            newVersion.addSeason(season);
            return;
        }

        seasons.push(season);
    }

    function getLastSeason() public view returns(address) {
        if (newVersionAddress != 0) {
            SeasonFactory newVersion = SeasonFactory(newVersionAddress);
            return newVersion.getLastSeason(); 
        }

        return seasons[seasons.length - 1];
    }
}

I also have a test:

[Fact]
public async Task Should_MigrateFactory()
{
    var factory = await TestHelper.GetFactoryAsync(_output);
    await factory.CreateSeasonAsync(TestSeasonAddress);
    var newVersion = await TestHelper.GetFactoryAsync(_output);
    await factory.MigrateToNewVersionAsync(newVersion.Address);

    var lastSeason = await factory.GetLastSeasonAsync();
    Assert.Null(lastSeason);
}

It's as C# test but it's quite clear what it does and it completely reprodusable via geth or something similar.

Expected result

Test pass

Actual result:

Nethereum.JsonRpc.Client.RpcResponseException : VM execution error.
   at Nethereum.JsonRpc.Client.RpcClient.HandleRpcError

when calling getLastSeason

Note

This test fails, but only on 1.11.x + (I've checked 1.11.0, 1.11.1, 1.11.8, 2.0.1)
When I change parity version to 1.10.7 it works without any issues.

[Tbaut]

Thanks for the report. Would you mind testing on v2 ?

[Pzixel]

@Tbaut Yep, I can confirm that I have the same error on 2.0.1

[cheme]

I also confirm.

[cheme]

False alarm, I was testing without the proper params in my chain. @Pzixel did your private network json contains "eip211Transition": "0x0", under "params" ?

[Pzixel]

Here is an entire JSON

  "params": {
    "maximumExtraDataSize": "0x20",
    "minGasLimit": "0x1388",
    "networkID": "0x2323",
    "gasLimitBoundDivisor": "0x400",
    "eip155Transition": 0,
    "eip140Transition": 0,
    "eip211Transition": 0,
    "eip214Transition": 0,
    "eip658Transition": 0,
    "wasmActivationTransition": 0
  }

so it does. Maybe it could be some combination of parameters, such as wasmActivationTransition?

---

You can run docker-compose up -d on this repo, deploy the contract and see results. It's 100% reproducible. Parity version may be modified via .env file in the repo root.

[cheme]

Nice work on those dockers. I forgot that I modified your contract to run it : switching

        return seasons[seasons.length - 1];

to

 if (seasons.length > 0) {
          return seasons[seasons.length - 1];
        } else {
          return 0;
        }

Indeed when going back to your version it breaks (when thinking about the way solc compile those array it should probably not, but I got to check a bit more).

[cheme]

Same behaviour with remix ide, solidity generate an evm check on lower bound, so I believe my code change makes sense. Can you test with my code change ?

[Pzixel]

Oh my god, it's indeed off-by-one error. Sorry for botherin you, guys.

So it's the opposite: the old parity VM was accepting the invalid code that new version handles and properly throws an exception. Thank you for your time.

[cheme]

No problem at all :) , I was happy to help (and do a bit of solidity).