Permissive fallback function (low severity)

[Dexaran]

Severity: low

Code snippet

https://github.com/EthereumCommonwealth/ethereum-classic-multisig/blob/master/contracts/MultisigWallet.sol#L42-L46

Description

Permissive fallback function is an antipattern in smart-contract development due to specifics of Ethereum. It should be noted that event handling is a well-known and a standard practice in programming.
There is a range of smart-contract calls that behave as events and execute a handler function in the destination contract. For example: token transfer of token contracts, name owner change of naming services and so on. Many others may be added in future.

Permissive fallback function executes successfully whenever a third party contract is trying to call a function that does not exist in the multi-sig wallet. In this case, a third party contract may rely on event handler functions that are not implemented in multi-sig wallet but the execution will succeed.

According to solidity issue#2630, a fallback function function can return corrupted values, even though it does not have return values in fact, thus violating the work flow of third-party contracts.

NOTE: This can not hurt the multi-sig wallet contract or its funds. This can only hurt third-party contracts that will interact with the multi-sig wallet contract.