Zero Div

[zapaz]

Five functions may reverts due to division by zero, when number of registered knot is zero

Theses reverts are demonstrated in 5 rules in this spec file :
https://github.com/zapaz/2023-01-19-blockswap-fv/blob/certora-contest/certora/specs/SyndicateIssues.spec

Inside public previewUnclaimedETHAsCollateralizedSlotOwner() function :
https://github.com/Certora/2023-01-blockswap-fv/blob/certora/contracts/syndicate/Syndicate.sol#L442-L443

uint256 accumulatedSoFar = accumulatedETHPerCollateralizedSlotPerKnot+ 
((calculateETHForFreeFloatingOrCollateralizedHolders() - 
lastSeenETHPerCollateralizedSlotPerKnot) / numberOfRegisteredKnots);

Inside public getUnprocessedETHForAllFreeFloatingSlot() function
also called by calculateNewAccumulatedETHPerCollateralizedSharePerKnot():
https://github.com/Certora/2023-01-blockswap-fv/blob/certora/contracts/syndicate/Syndicate.sol#L484

return ((calculateETHForFreeFloatingOrCollateralizedHolders() - 
lastSeenETHPerCollateralizedSlotPerKnot) / numberOfRegisteredKnots);

Inside internal _calculateCollateralizedETHOwedPerKnot() function :
https://github.com/Certora/2023-01-blockswap-fv/blob/certora/contracts/syndicate/Syndicate.sol#L577

uint256 collateralizedSLOTShareOfETHPerKnot = 
(collateralizedSLOTShareOfETH / numberOfRegisteredKnots);

Inside internal _calculateNewAccumulatedETHPerCollateralizedShare() function :
https://github.com/Certora/2023-01-blockswap-fv/blob/certora/contracts/syndicate/Syndicate.sol#L583

return (_ethSinceLastUpdate * PRECISION) / (numberOfRegisteredKnots * 4 ether);

[Vincent]

Assessment: Low

We will add more graceful error handling when number of knots is zero. Thank you

[teryanarmen]

The bug is in getUnprocessedETHForAllCollateralizedSlot not getUnprocessedETHForAllFreeFloatingSlot. Since this DOS is only in view functions which are not called by any critical functions, users can still unstake after all knots have been deregistered. Therefore I agree that this is low severity.