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Change execution order to avoid reentry through the _beforeTokenTransfer hook (#3611)

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Co-authored-by: Francisco <frangio.1@gmail.com>
This commit is contained in:
Hadrien Croubois
2022-08-19 15:33:19 +02:00
committed by GitHub
parent 17bc2dabe0
commit 98c3a79b57
2 changed files with 11 additions and 1 deletions
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3
CHANGELOG.md
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@ -6,11 +6,12 @@
* `ERC165Checker`: add `supportsERC165InterfaceUnchecked` for consulting individual interfaces without the full ERC165 protocol. ([#3339](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3339))
* `Address`: optimize `functionCall` by calling `functionCallWithValue` directly. ([#3468](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3468))
* `Address`: optimize `functionCall` functions by checking contract size only if there is no returned data. ([#3469](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3469))
* `GovernorCompatibilityBravo`: remove unused `using` statements ([#3506](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3506))
* `GovernorCompatibilityBravo`: remove unused `using` statements. ([#3506](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3506))
* `ERC20`: optimize `_transfer`, `_mint` and `_burn` by using `unchecked` arithmetic when possible. ([#3513](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3513))
* `ERC20FlashMint`: add an internal `_flashFee` function for overriding. ([#3551](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3551))
* `ERC721`: optimize transfers by making approval clearing implicit instead of emitting an event. ([#3481](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3481))
* `ERC721`: optimize burn by making approval clearing implicit instead of emitting an event. ([#3538](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3538))
* `ERC721`: Fix balance accounting when a custom `_beforeTokenTransfer` hook results in a transfer of the token under consideration. ([#3611](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3611))
* `ReentrancyGuard`: Reduce code size impact of the modifier by using internal functions. ([#3515](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3515))
* `SafeCast`: optimize downcasting of signed integers. ([#3565](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3565))
* `VestingWallet`: remove unused library `Math.sol`. ([#3605](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3605))

9
contracts/token/ERC721/ERC721.sol
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@ -282,6 +282,9 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
_beforeTokenTransfer(address(0), to, tokenId);
// Check that tokenId was not minted by `_beforeTokenTransfer` hook
require(!_exists(tokenId), "ERC721: token already minted");
_balances[to] += 1;
_owners[tokenId] = to;
@ -306,6 +309,9 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
_beforeTokenTransfer(owner, address(0), tokenId);
// Update ownership in case tokenId was transfered by `_beforeTokenTransfer` hook
owner = ERC721.ownerOf(tokenId);
// Clear approvals
delete _tokenApprovals[tokenId];
@ -338,6 +344,9 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
_beforeTokenTransfer(from, to, tokenId);
// Check that tokenId was not transfered by `_beforeTokenTransfer` hook
require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
// Clear approvals from the previous owner
delete _tokenApprovals[tokenId];