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feat(StrategyBase): add safety checks to prevent precision loss and edge cases #1599

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feat(StrategyBase): add safety checks to prevent precision loss and edge cases #1599

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10 changes: 10 additions & 0 deletions src/contracts/strategies/StrategyBase.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -126,6 +126,11 @@ contract StrategyBase is Initializable, Pausable, IStrategy, SemVerMixin {
uint256 virtualTokenBalance = _tokenBalance() + BALANCE_OFFSET;
// calculate the prior virtual balance to account for the tokens that were already transferred to this contract
uint256 virtualPriorTokenBalance = virtualTokenBalance - amount;

// Additional safety check to prevent precision loss
require(virtualPriorTokenBalance > 0, "VirtualPriorTokenBalanceZero");
require(virtualShareAmount > 0, "VirtualShareAmountZero");

newShares = (amount * virtualShareAmount) / virtualPriorTokenBalance;

// extra check for correctness / against edge case where share rate can be massively inflated as a 'griefing' sort of attack
Expand Down Expand Up @@ -169,6 +174,11 @@ contract StrategyBase is Initializable, Pausable, IStrategy, SemVerMixin {
// account for virtual shares and balance
uint256 virtualPriorTotalShares = priorTotalShares + SHARES_OFFSET;
uint256 virtualTokenBalance = _tokenBalance() + BALANCE_OFFSET;

// Additional safety checks for withdrawal calculations
require(virtualPriorTotalShares > 0, "VirtualPriorTotalSharesZero");
require(virtualTokenBalance > 0, "VirtualTokenBalanceZero");

// calculate ratio based on virtual shares and balance, being careful to multiply before dividing
amountOut = (virtualTokenBalance * amountShares) / virtualPriorTotalShares;

Expand Down