Position Risk Management Functionality Missing in Position Manager and dos in certain conditions

Summary

Protocol users who manage their positions through the PositionManager are not able to manage risk of their positions, by setting collateral to on and off. Which is a core functionality of every lending protocol. The missing functionality will doss users from withdrawing also in certain conditions.

Vulnerability Detail

For each collateral resrve the pool tracks whethere the user is using as collateral or not, this is set in the userConfigMap. Any user could set which reserve he is setting as collateral by calling the

function setUserUseReserveAsCollateral(address asset, uint256 index, bool useAsCollateral) external {
    _setUserUseReserveAsCollateral(asset, index, useAsCollateral);
  }

The PositionManager.sol which the protocol users, are expected to interact with, doesn't implement the setUserUseReserveAsCollateral(), which first of all leads to the inablity of protocol users to manage risk on their Positions. The second impact and the most severe is that Position holders will be dossed, in the protocols if the ltv of one of the reserve token being used, will be set to zero. In such an event, users are required to set the affected collateral to false in order to do operations that lowers the ltv like withdraw to function.

The doss will be done in the function validateHFandLtv() which will be called to check the health of a position is maintend after a withdrawal

  function validateHFAndLtv(
    mapping(address => mapping(bytes32 => DataTypes.PositionBalance)) storage _balances,
    mapping(address => DataTypes.ReserveData) storage reservesData,
    mapping(uint256 => address) storage reservesList,
    DataTypes.UserConfigurationMap memory userConfig,
    DataTypes.ExecuteWithdrawParams memory params
  ) internal view {
    DataTypes.ReserveData memory reserve = reservesData[params.asset];

    (, bool hasZeroLtvCollateral) = validateHealthFactor(_balances, reservesData, reservesList, userConfig, params.position, params.pool);

@>>    require(!hasZeroLtvCollateral || reserve.configuration.getLtv() == 0, PoolErrorsLib.LTV_VALIDATION_FAILED);
  }

In this case, if the user wants to withdraw other reserves that don't have 0 tlv, the transaction will revert.

Impact

missing core functions, that NFTPositionManager users are not able to use
NFTPositionManager are unable to manage to risk at all
Withdrawal operations in NFTPositionManager will be dossed in certain conditions

Code Snippet

https://github.com/sherlock-audit/2024-06-new-scope/blob/c8300e73f4d751796daad3dadbae4d11072b3d79/zerolend-one/contracts/core/pool/Pool.sol#L175C1-L177C4

Tool used

Manual Review

Recommendation

Implement the missing functionality in the NFTPositionManager.sol, to allow users to manage the risk on their NFTPosition

sherlock-audit / 2024-06-new-scope-judging

A2-security - Position Risk Management Functionality Missing in Position Manager and dos in certain conditions #398