Summary
When reseeding the barn fertilizing is set to true regardless of activeFertilizer
Relevant GitHub Links:
https://github.com/Cyfrin/2024-05-beanstalk-the-finale/blob/main/protocol/contracts/beanstalk/init/reseed/L2/ReseedBarn.sol#L65
Vulnerability Details
When the barn is reseed, the state variable fertilizing is set to true regardless of the activeFertilizer.
function init(
Fertilizers[] calldata fertilizerIds,
uint256 activeFertilizer,
uint256 fertilizedIndex,
uint256 unfertilizedIndex,
uint128 bpf
) external {
Fertilizer fertilizer = new Fertilizer();
TransparentUpgradeableProxy fertilizerProxy = new TransparentUpgradeableProxy(
address(fertilizer),
address(this),
abi.encode(IFertilizer.init.selector)
);
mintFertilizers(Fertilizer(address(fertilizerProxy)), fertilizerIds);
s.sys.season.fertilizing = true;
s.sys.fert.activeFertilizer = activeFertilizer;
s.sys.fert.fertilizedIndex = fertilizedIndex;
s.sys.fert.unfertilizedIndex = unfertilizedIndex;
s.sys.fert.bpf = bpf;
}
The state variable fertilizing represents if there is any activeFertilizer that has been bought by any user. So if the init function is called with 0 amount of activeFertilizer, the fertilizing boolean will be set to true and it can lead to unexpected results because there will be no activeFertilizer in the system.
Impact
Low
Tools Used
Manual review
Recommendations
Set the fertilizing variable depending on the activeFertilizer passed in the function:
function init(
Fertilizers[] calldata fertilizerIds,
uint256 activeFertilizer,
uint256 fertilizedIndex,
uint256 unfertilizedIndex,
uint128 bpf
) external {
// deploy fertilizer implmentation.
Fertilizer fertilizer = new Fertilizer();
// deploy fertilizer proxy. Set owner to beanstalk.
TransparentUpgradeableProxy fertilizerProxy = new TransparentUpgradeableProxy(
address(fertilizer),
address(this),
abi.encode(IFertilizer.init.selector)
);
mintFertilizers(Fertilizer(address(fertilizerProxy)), fertilizerIds);
- s.sys.season.fertilizing = true;
+ if(activeFertilizer > 0) s.sys.season.fertilizing = true;
s.sys.fert.activeFertilizer = activeFertilizer;
s.sys.fert.fertilizedIndex = fertilizedIndex;
s.sys.fert.unfertilizedIndex = unfertilizedIndex;
s.sys.fert.bpf = bpf;
}