Submitted by CipherSleuths, also found by BARW
https://github.com/re-nft/smart-contracts/blob/3ddd32455a849c3c6dc3c3aad7a33a6c9b44c291/src/policies/Stop.sol#L265 
https://github.com/re-nft/smart-contracts/blob/3ddd32455a849c3c6dc3c3aad7a33a6c9b44c291/src/modules/PaymentEscrow.sol#L100
If an order involves erc777 token for a pay order then in the tokensReceived callback the renter can create DOS situation resulting in the lenders assets being stuck in the rental safe.
ERC777 token standard which is backward compatible with erc20 implies that on the transfer of the tokens the recipient can implement a tokensReceived hook to notify of any increment of the balance.
Now suppose a pay order is created with an erc 777 consideration asset as there is no restriction on that and also the eip specifies that
So the tokensReceived hook is optional for a transfer/transferFrom call. Hence sending the assets from the lenders wallet to the escrow contract shouldnt be an issue.
Now when the rental period is over or in/between, the stopRent method in stop policy is called, which calls settlePayment in escrow module. Now on the token transfer
The tokensReceived hook if implemented by the renter, would be called and they could just revert the tx inside the tokensReceived hook which would mean that the assets lent by the lender are locked forever.
It is recommended to prohibit erc777 tokens from being used as consideration items.
0xean (Judge) decreased severity to Medium and commented:
Alec1017 (reNFT) confirmed
reNFT mitigated:
Status: Mitigation confirmed. Full details in reports from EV_om, sin1st3r__ and juancito.
