Optimizer bug with memory operations with Solidity `0.8.13`

[code423n4]

Lines of code

https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/targets/Transfer.sol#L18-L22 https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/targets/Transfer.sol#L222-L227 https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/targets/Transfer.sol#L341-L347 https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/targets/Transfer.sol#L474-L480

Vulnerability details

Optimizer bug with memory operations with Solidity 0.8.13

Several contracts have functions performing low level assembly memory operations: MerkleBase.sol, Transfer.sol. Due to a bug in the optimizer for Solidity 0.8.13, these operations can be omitted by the compiler. This would result in several functions breaking, including key transfer functions such as Transfer.ERC20Transfer or Transfer.ERC721TransferFrom

Impact

High

Proof Of Concept

see this article

use of `mstore` or `returndatacopy` can be omitted by compiler 0.8.13

Mitigation

Update the compiler's versions to 0.8.15

[ecmendenhall]

https://github.com/code-423n4/2022-07-fractional-findings/issues/604

[0x0aa0]

Duplicate of #604

[HardlyDifficult]

No POC demonstrating that these contracts are impacted - lowering risk and merging with the warden's QA report #628