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code-423n4 / 2022-10-thegraph-findings

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Missing gap variable for upgradeable base contract #301

Closed code423n4 closed 1 year ago

code423n4 commented 1 year ago

Lines of code

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/upgrades/GraphUpgradeable.sol#L1-L66

Vulnerability details

Impact

Possibility of storage collisions after upgrade.

Proof of Concept

GraphUpgradeable.sol is an upgradeable base contract whose inheriting contracts may introduce new variables. In order to be able to add new variables to the upgradeable abstract contract without causing storage collisions, a storage gap should be added to the upgradeable abstract contract. If no storage gap is added, when the upgradable abstract contract introduces new variables, it may override the variables in the inheriting contract. (For reference)

Recommended Mitigation Steps

Consider adding a storage gap at the end of the contract:

uint256[50] private __gap;
trust1995 commented 1 year ago

Dup of #306

0xean commented 1 year ago

closing as dupe of #302 - wardens QA