Part 2

Summary

The function _updateCreditDelegations updates vaults' credit delegations to connected markets.
The issue occurs in this line:

If newCreditDelegationUsdX18 is zero or less than previousCreditDelegationUsdX18, it will revert. This can happen when the vault's current credit capacity drops below its previous value.

Vulnerability Details

creditDeltaUsdX18 is a UD60x18 (unsigned decimal) type. When previousCreditDelegationUsdX18 > newCreditDelegationUsdX18, the subtraction:

results in a negative number, which unsigned types do not support, causing a revert.

Impact

• The function will always revert when newCreditDelegationUsdX18 <= previousCreditDelegationUsdX18, meaning the vault cannot reduce its credit delegation to it's connected markets

• the vault cannot update it's state through recalculateVaultsCreditCapacity, as this function calls _updateCreditDelegations, meaning vault will stop updating it's states, users will lose rewards, depositors won't be able to withdraw funds from zlpvault

Recommendation

Use signed integers (SD59x18) for credit delta calculations.

This will eliminate the revert issue and can reduce delegated credit from market in case vault's credit capacity is less than or equal to zero