solidity-security

Apply the Checks-Effects-Interactions pattern by updating state before external calls, and add OpenZeppelin's ReentrancyGuard nonReentrant modifier to all state-changing functions. CEI alone does not stop cross-function reentrancy, so use both defenses together.

Never use Uniswap slot0 or reserve ratios as price oracles since flash loans can move them within one transaction. Use Chainlink feeds with staleness checks or Uniswap V3 TWAP with a 30-minute window, which makes manipulation economically infeasible.

Slither is a fast static analyzer with low false positives, suited for CI on every pull request. Mythril uses symbolic execution to find deep logic bugs but is slower, making it better for pre-deployment analysis of high-value contracts.

No. Solidity 0.8 checked math covers standard arithmetic on standard types, but does not protect unchecked blocks, assembly, bitwise operations, or downcasts like uint256 to uint128. Review all unchecked blocks and use OpenZeppelin SafeCast for downcasts.

USDT requires resetting the allowance to zero before setting a new value, and its approve returns no boolean. Use OpenZeppelin SafeERC20's forceApprove, which handles the reset automatically and works with non-standard tokens like USDT and BNB.

Include _disableInitializers in the implementation constructor, protect _authorizeUpgrade with access control, and only append new storage variables using the __gap pattern. Validate storage layout between versions with OpenZeppelin upgrades tooling and test upgrades via fork tests.