ERC20 transfers for stakeToken's is not updating the rewards process

Summary

Since the stakeToken's are ERC20 the transfers of these tokens should also change the rewards since the ownership of the tokens will change after the transfer

Vulnerability Detail

As we can see, when an account mints new stake tokens, the fee rewards are updated:

function executeMintStakeToken(
        uint256 requestId,
        Mint.Request memory mintRequest
    ) external returns (uint256 stakeAmount) {
        -> FeeRewardsProcess.updateAccountFeeRewards(mintRequest.account, mintRequest.stakeToken);
       //..
    }

This is crucial to ensure fair accrual of rewards for the users.

However, there is another case where the account's fee rewards will change: when they simply transfer their tokens. All stake tokens are ERC20 tokens, and they have transfer functions that users can use.

Impact

Unfair accrual of rewards, high.

Code Snippet

https://github.com/sherlock-audit/2024-05-elfi-protocol/blob/8a1a01804a7de7f73a04d794bf6b8104528681ad/elfi-perp-contracts/contracts/process/MintProcess.sol#L68-L91

https://github.com/sherlock-audit/2024-05-elfi-protocol/blob/8a1a01804a7de7f73a04d794bf6b8104528681ad/elfi-perp-contracts/contracts/vault/StakeToken.sol#L7-L25

Tool used

Manual Review

Recommendation

Override the transfer hook in ERC20 and update the rewards whenever the tokens are transferred

Duplicate of #146

sherlock-audit / 2024-05-elfi-protocol-judging

mstpr-brainbot - ERC20 transfers for stakeToken's is not updating the rewards process #271