Bid Beasts
First Flight #49
Beginner FriendlyFoundrySolidityNFT
100 EXP
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Submission Details
Severity: low
Valid

Incorrect requiredAmount validation

r4ck3

Validation prohibits users of bidding the minPrice to the nft listing.

Description

  • When listing is created and there are no bids on it yet, user is able to make a bid on that listing that is equal to the minPrice of that listing.

function placeBid(uint256 tokenId) external payable isListed(tokenId) {
Listing storage listing = listings[tokenId];
address previousBidder = bids[tokenId].bidder;
.
.
.
if (previousBidAmount == 0) {
​
requiredAmount = listing.minPrice;
@> require(msg.value > requiredAmount, "First bid must be > min price");
listing.auctionEnd = block.timestamp + S_AUCTION_EXTENSION_DURATION;
emit AuctionExtended(tokenId, listing.auctionEnd);
.
.
.

Risk

Likelihood:

  • This happens when there are no bids on the listing and the bidder wants to bid the minPrice to it.

Impact:

  • Bidder is unable to make a bid, call reverts.

Proof of Concept

Placing this in the test contract and executing will result in a revert and a bidder being unable to make a bid of MIN_PRICE. MIN_PRICE is the amount of eth that is used inside of a listing.minPrice for that nft.

function testBidMinPrice() public {
_mintNFT();
_listNFT();
vm.prank(BIDDER_1);
market.placeBid{value:MIN_PRICE}(TOKEN_ID);
vm.expectRevert();
}

Recommended Mitigation

By simply changing greater than to greater equals will allow bidder to bid the minPrice.

function placeBid(uint256 tokenId) external payable isListed(tokenId) {
Listing storage listing = listings[tokenId];
address previousBidder = bids[tokenId].bidder;
.
.
.
if (previousBidAmount == 0) {
​
requiredAmount = listing.minPrice;
- require(msg.value > requiredAmount, "First bid must be > min price");
+ require(msg.value >= requiredAmount, "First bid must be >= min price");
listing.auctionEnd = block.timestamp + S_AUCTION_EXTENSION_DURATION;
emit AuctionExtended(tokenId, listing.auctionEnd);
.
.
.
Updates

Lead Judging Commences

cryptoghost Lead Judge 2 months ago
Submission Judgement Published
Validated
Assigned finding tags:

BidBeasts Marketplace: First Bid > Instead of >=

First bid validation uses > instead of >=, preventing valid starting bids.

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