2.9 KiB
eip | title | description | author | discussions-to | status | type | category | created | requires |
---|---|---|---|---|---|---|---|---|---|
5920 | PAY opcode | Introduces a new opcode, PAY, to send ether to an address without calling any of its functions | Gavin John (@Pandapip1), Zainan Victor Zhou (@xinbenlv) | https://ethereum-magicians.org/t/eip-5920-pay-opcode/11717 | Review | Standards Track | Core | 2022-03-14 | 2929 |
Abstract
This EIP introduces a new opcode, PAY
, taking two stack parameters, addr
and val
, that transfers val
wei to the address addr
without calling any of its functions.
Motivation
Currently, to send ether to an address requires you to call a function of that address, which has a few issues. First of all, it opens a reentrancy attack vector, as the recipient can call back into the sender. Secondly, it opens a DoS vector, so parent functions must be cognizant of the possibility that the recipient will run out of gas or revert. Finally, the CALL
opcode is needlessly expensive for simple ether transfers, as it requires the memory and stack to be expanded, the recipient's full data including code and memory to be loaded, and finally needs to execute a call, which might do other unintentional operations. Having a dedicated opcode for ether transfers solves all of these issues, and would be a useful addition to the EVM.
Specification
Parameter | Value |
---|---|
PAY_OPCODE |
0xf9 |
GAS_COST |
3000 |
A new opcode is introduced: PAY
(PAY_OPCODE
), which:
- Pops two values from the stack:
addr
thenval
. - Transfers
val
wei from the executing address to the addressaddr
. Ifaddr
is the zero address, instead,val
wei is burned from the executing address.
The cost of this opcode is GAS_COST
. If addr
is not the zero address, the EIP-2929 account access costs are also incurred (this includes the 25k gas cost for adding a new account to the state).
Rationale
Gas pricing
The gas pricing is that of a CALL
with a positive msg.value
, but without any memory expansion costs or "gas sent with call" costs, with a gas reduction of 500
to compensate for the reduced amount of computation.
Argument order
The order of arguments mimicks that of CALL
, which pops addr
before val
. Beyond consistency, though, this ordering aids validators pattern-matching MEV opportunities, so PAY
always appears immediately after COINBASE
.
Backwards Compatibility
This change requires a hard fork.
Security Considerations
Existing contracts should not rely on their balance being under their control, since it is already possible to send ether to an address without calling it, by creating a temporary contract and immediately SELFDESTRUCT
ing it, sending the ether to an arbitrary address. However, this opcode does make this process cheaper for already-vulnerable contracts.
Copyright
Copyright and related rights waived via CC0.