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Add ERC2771Forwarder fuzz tests for avoiding loss of unused ETH (#4396)

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Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Co-authored-by: Francisco <fg@frang.io>
This commit is contained in:
Ernesto García
2023-07-07 18:56:49 -06:00
committed by GitHub
parent 0053ee040a
commit f5bf7233cb
2 changed files with 171 additions and 6 deletions
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12
contracts/metatx/ERC2771Forwarder.sol
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@ -53,7 +53,7 @@ contract ERC2771Forwarder is EIP712, Nonces {
bytes signature;
}
bytes32 private constant _FORWARD_REQUEST_TYPEHASH =
bytes32 internal constant _FORWARD_REQUEST_TYPEHASH =
keccak256(
"ForwardRequest(address from,address to,uint256 value,uint256 gas,uint256 nonce,uint48 deadline,bytes data)"
);
@ -255,7 +255,7 @@ contract ERC2771Forwarder is EIP712, Nonces {
abi.encodePacked(request.data, request.from)
);
_checkForwardedGas(request);
_checkForwardedGas(gasleft(), request);
emit ExecutedForwardRequest(signer, currentNonce, success);
}
@ -270,10 +270,10 @@ contract ERC2771Forwarder is EIP712, Nonces {
*
* It reverts consuming all the available gas if the forwarded gas is not the requested gas.
*
* IMPORTANT: This function should be called exactly the end of the forwarded call. Any gas consumed
* in between will make room for bypassing this check.
* IMPORTANT: The `gasLeft` parameter should be measured exactly at the end of the forwarded call.
* Any gas consumed in between will make room for bypassing this check.
*/
function _checkForwardedGas(ForwardRequestData calldata request) private view {
function _checkForwardedGas(uint256 gasLeft, ForwardRequestData calldata request) private pure {
// To avoid insufficient gas griefing attacks, as referenced in https://ronan.eth.limo/blog/ethereum-gas-dangers/
//
// A malicious relayer can attempt to shrink the gas forwarded so that the underlying call reverts out-of-gas
@ -295,7 +295,7 @@ contract ERC2771Forwarder is EIP712, Nonces {
// - req.gas >= X * 63 / 64
// In other words if req.gas < X * 63 / 64 then req.gas / 63 <= gasleft(), thus if the relayer behaves honestly
// the forwarding does not revert.
if (gasleft() < request.gas / 63) {
if (gasLeft < request.gas / 63) {
// We explicitly trigger invalid opcode to consume all gas and bubble-up the effects, since
// neither revert or assert consume all gas since Solidity 0.8.0
// https://docs.soliditylang.org/en/v0.8.0/control-structures.html#panic-via-assert-and-error-via-require