The use of transferFrom() on NFTs may lead to loss of NFTs if not handled appropriately
The standard `transferFrom()` function does not verify whether the recipient address can accept and manage NFTs (i.e., whether the address is a smart contract that implements the necessary interface to handle ERC-721 tokens). If the NFT is sent to a contract that cannot handle it, the token may be irretrievably lost.
```javascript
function finalizeLiquidation(address userAddress) external nonReentrant onlyStabilityPool {
if (!isUnderLiquidation[userAddress]) revert NotUnderLiquidation();
// update state
ReserveLibrary.updateReserveState(reserve, rateData);
if (block.timestamp <= liquidationStartTime[userAddress] + liquidationGracePeriod) {
revert GracePeriodNotExpired();
}
UserData storage user = userData[userAddress];
uint256 userDebt = user.scaledDebtBalance.rayMul(reserve.usageIndex);
isUnderLiquidation[userAddress] = false;
liquidationStartTime[userAddress] = 0;
// Transfer NFTs to Stability Pool
for (uint256 i = 0; i < user.nftTokenIds.length; i++) {
uint256 tokenId = user.nftTokenIds[i];
user.depositedNFTs[tokenId] = false;
@>> raacNFT.transferFrom(address(this), stabilityPool, tokenId);
}
delete user.nftTokenIds;
// Burn DebtTokens from the user
(uint256 amountScaled, uint256 newTotalSupply, uint256 amountBurned, uint256 balanceIncrease) = IDebtToken(reserve.reserveDebtTokenAddress).burn(userAddress, userDebt, reserve.usageIndex);
// Transfer reserve assets from Stability Pool to cover the debt
IERC20(reserve.reserveAssetAddress).safeTransferFrom(msg.sender, reserve.reserveRTokenAddress, amountScaled);
// Update user's scaled debt balance
user.scaledDebtBalance -= amountBurned;
reserve.totalUsage = newTotalSupply;
// Update liquidity and interest rates
ReserveLibrary.updateInterestRatesAndLiquidity(reserve, rateData, amountScaled, 0);
emit LiquidationFinalized(stabilityPool, userAddress, userDebt, getUserCollateralValue(userAddress));
}
```
Using `safeTransferFrom()` is recommended as it includes an additional check to ensure that the destination address can properly interact with NFTs.
```diff
//code
for (uint256 i = 0; i < user.nftTokenIds.length; i++) {
uint256 tokenId = user.nftTokenIds[i];
user.depositedNFTs[tokenId] = false;
- raacNFT.transferFrom(address(this), stabilityPool, tokenId);
+ raacNFT.safeTransferFrom(address(this), stabilityPool, tokenId);
}
delete user.nftTokenIds;
```
