Avci - admin in level 0 is locked and impossible to use

[sherlock-admin]

Avci

high

admin in level 0 is locked and impossible to use

Summary

admin in level 0 is locked and impossible to use

Vulnerability Detail

the protocol has the levels for admins and it starts from 0 to 15

  function getLocalHatLevel(uint256 _hatId) public pure returns (uint32 level) {
        if (_hatId & uint256(type(uint224).max) == 0) return 0;
        if (_hatId & uint256(type(uint208).max) == 0) return 1;
        if (_hatId & uint256(type(uint192).max) == 0) return 2;
        if (_hatId & uint256(type(uint176).max) == 0) return 3;
        if (_hatId & uint256(type(uint160).max) == 0) return 4;
        if (_hatId & uint256(type(uint144).max) == 0) return 5;
        if (_hatId & uint256(type(uint128).max) == 0) return 6;
        if (_hatId & uint256(type(uint112).max) == 0) return 7;
        if (_hatId & uint256(type(uint96).max) == 0) return 8;
        if (_hatId & uint256(type(uint80).max) == 0) return 9;
        if (_hatId & uint256(type(uint64).max) == 0) return 10;
        if (_hatId & uint256(type(uint48).max) == 0) return 11;
        if (_hatId & uint256(type(uint32).max) == 0) return 12;
        if (_hatId & uint256(type(uint16).max) == 0) return 13;
        return 14;
    }

but in the function isAdminOfHat it actually has else part for who is not Tophat

and it getting those hat wearers levels

          } else {
            // if we get here, _hatId is not a tophat of any kind
            // get the local tree level of _hatId's admin
            adminLocalHatLevel = getLocalHatLevel(_hatId) - 1;
        }

but it decreases -1 and it will cause error on admin level 0 therefore admin level 0 is actually means nothing and its useless at all after this happens all time

Impact

will cause an error on admin level 0 therefore admin level 0 is actually means nothing and its useless at all after this happening all time

Code Snippet

 function isAdminOfHat(address _user, uint256 _hatId) public view returns (bool isAdmin) {
        uint256 linkedTreeAdmin;
        uint32 adminLocalHatLevel;
        if (isLocalTopHat(_hatId)) {
            linkedTreeAdmin = linkedTreeAdmins[getTopHatDomain(_hatId)];
            if (linkedTreeAdmin == 0) {
                // tree is not linked
                return isAdmin = isWearerOfHat(_user, _hatId);
            } else {
                // tree is linked
                if (isWearerOfHat(_user, linkedTreeAdmin)) {
                    return isAdmin = true;
                } // user wears the treeAdmin
                else {
                    adminLocalHatLevel = getLocalHatLevel(linkedTreeAdmin);
                    _hatId = linkedTreeAdmin;
                }
            }
        } else {
            // if we get here, _hatId is not a tophat of any kind
            // get the local tree level of _hatId's admin
            adminLocalHatLevel = getLocalHatLevel(_hatId) - 1;
        }

        // search up _hatId's local address space for an admin hat that the _user wears
        while (adminLocalHatLevel > 0) {
            if (isWearerOfHat(_user, getAdminAtLocalLevel(_hatId, adminLocalHatLevel))) {
                return isAdmin = true;
            }
            // should not underflow given stopping condition > 0
            unchecked {
                --adminLocalHatLevel;
            }
        }

        // if we get here, we've reached the top of _hatId's local tree, ie the local tophat
        // check if the user wears the local tophat
        if (isWearerOfHat(_user, getAdminAtLocalLevel(_hatId, 0))) return isAdmin = true;

        // if not, we check if it's linked to another tree
        linkedTreeAdmin = linkedTreeAdmins[getTopHatDomain(_hatId)];
        if (linkedTreeAdmin == 0) {
            // tree is not linked
            // we've already learned that user doesn't wear the local tophat, so there's nothing else to check; we return false
            return isAdmin = false;
        } else {
            // tree is linked
            // check if user is wearer of linkedTreeAdmin
            if (isWearerOfHat(_user, linkedTreeAdmin)) return true;
            // if not, recurse to traverse the parent tree for a hat that the user wears
            isAdmin = isAdminOfHat(_user, linkedTreeAdmin);
        }
    }

https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/Hats.sol#L852

Tool used

Manual Review

Recommendation

consider modifying contract to the way that admins should start at 1 level by default

• admin hat level should starts at 1

Duplicate of #131