HPB bankruptcy on settle #675
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- if there's only a tiny amount of deposit (2) backed by 2 LPs in HPB then the collateralUsed to settle is calculated as 0 due to rounding (vars.collateralUsed = Maths.wdiv(vars.scaledDeposit, vars.price)) - this results in removing deposit (2) and not adding any collateral into bucket, leaving an amount of 2 LPs that is not backed by any asset - fixed by declaring bucket bankruptcy in case settle leaves bucket with 0 collateral, 0 deposit but LPs > 0 - added check for deposit to remove to be min of available deposit in bucket / calculated deposit for settle in order to prevent any potential underflow - unit test
grandizzy
requested review from
EdNoepel,
ith-harvey,
mattcushman,
MikeHathaway and
prateek105
EdNoepel
approved these changes
Mar 9, 2023
| uint256 depositToRemove; // [WAD] deposit used by settle auction | ||
| uint256 hpbCollateral; // [WAD] amount of collateral in HPB bucket | ||
| uint256 hpbUnscaledDeposit; // [WAD] unscaled amount of of quote tokens in HPB bucket before settle | ||
| uint256 hpbLPs; // [WAD] amount of LPs in HPB bucket |
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note to self: 3 new local vars lines 111-113
| vars.hpbCollateral = hpb.collateral + vars.collateralUsed; | ||
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| // set amount to remove as min of calculated amount and available deposit (to prevent rounding issues) | ||
| vars.unscaledDeposit = Maths.min(vars.hpbUnscaledDeposit, vars.unscaledDeposit); |
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nit: alignment of Maths.min call
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| Deposits.unscaledRemove(deposits_, vars.index, vars.unscaledDeposit); // remove amount to settle debt from bucket (could be entire deposit or only the settled debt) | ||
| } | ||
| Bucket storage hpb = buckets_[vars.index]; |
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Appreciate naming this hpb and not settlementBucket. I reviewed and confirmed this is always the HPB; the user cannot specify the index.
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vars.collateralUsed = Maths.wdiv(vars.scaledDeposit, vars.price))