diff --git a/.changeset/unlucky-beans-obey.md b/.changeset/unlucky-beans-obey.md new file mode 100644 index 00000000000..e472d3c6cb6 --- /dev/null +++ b/.changeset/unlucky-beans-obey.md @@ -0,0 +1,5 @@ +--- +'openzeppelin-solidity': patch +--- + +`ERC2771Context`: Return the forwarder address whenever the `msg.data` of a call originating from a trusted forwarder is not long enough to contain the request signer address (i.e. `msg.data.length` is less than 20 bytes), as specified by ERC-2771. diff --git a/contracts/metatx/ERC2771Context.sol b/contracts/metatx/ERC2771Context.sol index 8cc14b9f400..0996fcbd915 100644 --- a/contracts/metatx/ERC2771Context.sol +++ b/contracts/metatx/ERC2771Context.sol @@ -22,7 +22,7 @@ abstract contract ERC2771Context is Context { } function _msgSender() internal view virtual override returns (address sender) { - if (isTrustedForwarder(msg.sender)) { + if (isTrustedForwarder(msg.sender) && msg.data.length >= 20) { // The assembly code is more direct than the Solidity version using `abi.decode`. /// @solidity memory-safe-assembly assembly { diff --git a/test/metatx/ERC2771Context.test.js b/test/metatx/ERC2771Context.test.js index 6c298d3d9f0..cfa5e7298e0 100644 --- a/test/metatx/ERC2771Context.test.js +++ b/test/metatx/ERC2771Context.test.js @@ -12,6 +12,8 @@ const ContextMockCaller = artifacts.require('ContextMockCaller'); const { shouldBehaveLikeRegularContext } = require('../utils/Context.behavior'); contract('ERC2771Context', function (accounts) { + const [, anotherAccount] = accounts; + beforeEach(async function () { this.forwarder = await MinimalForwarder.new(); this.recipient = await ERC2771ContextMock.new(this.forwarder.address); @@ -73,6 +75,15 @@ contract('ERC2771Context', function (accounts) { const { tx } = await this.forwarder.execute(req, sign); await expectEvent.inTransaction(tx, ERC2771ContextMock, 'Sender', { sender: this.sender }); }); + + it('returns the original sender when calldata length is less than 20 bytes (address length)', async function () { + // The forwarder doesn't produce calls with calldata length less than 20 bytes + const recipient = await ERC2771ContextMock.new(anotherAccount); + + const { receipt } = await recipient.msgSender({ from: anotherAccount }); + + await expectEvent(receipt, 'Sender', { sender: anotherAccount }); + }); }); describe('msgData', function () {