GimelSec - Nested linked trees could cause recursion stack overflow

[sherlock-admin]

GimelSec

medium

Nested linked trees could cause recursion stack overflow

Summary

There is no limit on the depth of nested linked trees. Hats protocol could suffer from recursion stack overflow because of the Solidity stack slots limit.

Vulnerability Detail

There are many recursive functions in the Hats.sol and HatsIdUtilities.sol. And they would traverse the linked trees. If the depth of the linked trees are too large, those functions could suffer from recursion stack overflow because of the Solidity stack slots limit.

Impact

Those recursive functions suffer from recursion stack overflow.

Code Snippet

https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/HatsIdUtilities.sol#L96
https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/HatsIdUtilities.sol#L184
https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/HatsIdUtilities.sol#L151
https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/HatsIdUtilities.sol#L194
https://github.com/Hats-Protocol/hats-protocol/blob/fafcfdf046c0369c1f9e077eacd94a328f9d7af0/src/Hats.sol#L831

Tool used

Manual Review

Recommendation

Don’t use recursive functions, use loops instead. Or add a limit on the depth of linked trees.

Duplicate of #96