EIP-1285: Increase Gcallstipend gas in the CALL opcode
Simple Summary
Increase the Gcallstipend
fee parameter in the CALL
opcode from 2,300
to 3,500
gas units.
Abstract
Currently, the CALL
opcode forwards a stipend of 2,300
gas units for a non zero value CALL
operations where a contract is called. This stipend is given to the contract to allow execution of its fallback
function. The stipend given is intentionally small in order to prevent the called contract from spending the call gas or performing an attack (like re-entrancy).
While the stipend is small it should still give the sufficient gas required for some cheap opcodes like LOG
, but it's not enough for some more complex and modern logics to be implemented.
This EIP proposes to increase the given stipend from 2,300
to 3,500
to increase the usability of the fallback
function.
Motivation
The main motivation behind this EIP is to allow simple fallback functions to be implemented for contracts following the "Proxy"
pattern. Simply explained, a "Proxy Contract"
is a contract which use DELEGATECALL
in its fallback
function to behave according to the logic of another contract and serve as an independent instance for the logic of the contract it points to.
This pattern is very useful for saving gas per deployment (as Proxy contracts are very lean) and it opens the ability to experiment with upgradability of contracts.
On average, the DELEGATECALL
functionality of a proxy contract costs about 1,000
gas units.
When a contract transfers ETH to a proxy contract, the proxy logic will consume about 1,000
gas units before the fallback
function of the logic contract will be executed. This leaves merely about 1,300 gas units for the execution of the logic. This is a severe limitation as it is not enough for an average LOG
operation (it might be enough for a LOG
with one parameter).
By slightly increasing the gas units given in the stipend we allow proxy contracts have proper fallback
logic without increasing the attack surface of the calling contract.
Specification
Increase the Gcallstipend
fee parameter in the CALL
opcode from 2,300
to 3,500
gas unit.
The actual change to the Ethereum clients would be to change the CallStipend
they store as a constant.
For an implementation example you can find a Geth client implementation linked here. The actual change to the code can be found here.
Rationale
The rational for increasing the Gcallstipend
gas parameter by 1,200
gas units comes from the cost of performing DELEGATECALL
and SLOAD
with a small margin for some small additional operations. All while still keeping the stipend relatively small and insufficient for accessing the storage or changing the state.
Backwards Compatibility
This EIP requires a backwards incompatible change for the Gcallstipend
gas parameter in the CALL
opcode.
Copyright
Copyright and related rights waived via CC0.