Submission Details
Severity:
Debt gets subtracted twice when refinancing a loan
Summary
The debt of the loan at hand gets subtracted twice when refinancing it through refinance().
Vulnerability Details
Lender.sol's refinance() subtracts debt from the pool balance twice, which will lock another debt amount's worth of tokens in the new pool.
function refinance(Refinance[] calldata refinances) public {
for (uint256 i = 0; i < refinances.length; i++) {
...
// update the old lenders pool
_updatePoolBalance(
oldPoolId,
pools[oldPoolId].poolBalance + loan.debt + lenderInterest
);
pools[oldPoolId].outstandingLoans -= loan.debt;
// @audit deducting from the balance #1
_updatePoolBalance(poolId, pools[poolId].poolBalance - debt);
pools[poolId].outstandingLoans += debt;
...
// @audit deducting from the balance #2
pools[poolId].poolBalance -= debt;
...
}
}
Impact
It will lock debt * 2 worth of tokens in the new pool.
Tools Used
Manual Review
Recommendations
Consider removing the following line: https://github.com/Cyfrin/2023-07-beedle/blob/main/src/Lender.sol#L698
Prize pool breakdown
Total prize
20,000 USDC
nSLOC
70628 USDC / LOC
18,000 USDC
2,000 USDC
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