check potential error before Commit

[wanwiset25]

Proposed changes

The StateDB type utilizes a dbErr to track database errors. It is employed by both the consensus core and the VM which are not designed to manage such errors directly.

Errors encountered during database operations are recorded in dbErr using the SetError function. During a Commit, functions like deleteStateObject, updateStateObject, and getStateObject are called based on the current state of stateObject to manage trie node data for deletion, update, or retrieval. If a data node is missing, dbErr is set accordingly.

To avoid committing erroneous state, check the dbErr before performing Commit action.

This issue is raised by the auditing team
ref: https://github.com/ethereum/go-ethereum/pull/21039/files

Types of changes

What types of changes does your code introduce to XDC network?
Put an ✅ in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)
• Regular KTLO or any of the maintaince work. e.g code style
• CICD Improvement

Impacted Components

Which part of the codebase this PR will touch base on,

Put an ✅ in the boxes that apply

• Consensus
• Account
• Network
• Geth
• Smart Contract
• External components
• Not sure (Please specify below)

Checklist

Put an ✅ in the boxes once you have confirmed below actions (or provide reasons on not doing so) that

• This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• Tested the backwards compatibility.
• Tested with XDC nodes running this version co-exist with those running the previous version.
• Relevant documentation has been updated as part of this PR
• N/A

[gzliudan]

dbErr does not mean a real error, eg:

func (self *StateDB) GetCodeSize(addr common.Address) int {
	stateObject := self.getStateObject(addr)
	if stateObject == nil {
		return 0
	}
	if stateObject.code != nil {
		return len(stateObject.code)
	}
	size, err := self.db.ContractCodeSize(stateObject.addrHash, common.BytesToHash(stateObject.CodeHash()))
	if err != nil {
		self.setError(err)
	}
	return size
}

The function GetCodeSize set dbErr when the account does not exist, but the return value size 0 is right.

[wanwiset25]

Would account not existing not be an error? I don't know the repo deep enough about this.

In go-ethereum GetCodeSize is handled the same way. Using setError instead of the usual return nil, err pattern.

func (s *StateDB) GetCodeSize(addr common.Address) int {
	stateObject := s.getStateObject(addr)
	if stateObject != nil {
		return stateObject.CodeSize()
	}
	return 0
}

func (s *stateObject) CodeSize() int {
	if s.code != nil {
		return len(s.code)
	}
	if bytes.Equal(s.CodeHash(), types.EmptyCodeHash.Bytes()) {
		return 0
	}
	size, err := s.db.db.ContractCodeSize(s.address, common.BytesToHash(s.CodeHash()))
	if err != nil {
		s.db.setError(fmt.Errorf("can't load code size %x: %v", s.CodeHash(), err))
	}
	return size
}