EIP-2677: Limit size of `initcode`
Simple Summary
Enforce a maximum size limit (max_initcode_size
) of 49152
(0xc000
) for initcode
.
Abstract
Enforce a maximum size limit (max_initcode_size
) for initcode
. If the size of initcode
exceeds max_initcode_size
, then contract creation fails with an out of gas error.
Since EIP-170 was implemented, there has been a size limit of 24576
(0x6000
) on contract code. We propose to also limit the size of executable code to 2x
the above limit, i.e. 49152
(0xc000
).
This also leads to two nice properties:
- instruction offset in code fits 16-bit value,
- code size fits 16-bit value.
Motivation
When a client executes initcode
, the client has to perform a jumpdest analysis. In some cases, the client also performs a hash
of the code:
- To use as a key in a mapping containing result of a jumpdest analysis
- To use for address calculation within
CREATE2
.
The work performed during a jumpdest analysis scales linearly with the size of the code. Currently, a transaction can expand the memory once, and reuse the same memory segment (with minor modifications) to force the client to perform a lot of analysis/hashing, leading to slow block processing.
Historically, this was exploited in June 2017, precipitating the 1.6.5-patch release of geth
The work performed during address calculation within CREATE2
is charged in proportion with size of the code.
Specification
There are three situations where this is applicable:
CREATE
,CREATE2
,- creation using a transaction with empty receiver.
In all these (and future) cases, the EVM should fail with Out Of Gas error if the code has a length more than max_initcode_size
.
Rationale
TBA
Backwards Compatibility
This EIP requires a "network upgrade", since it modifies consenus-rules.
Security Considerations
For client implementations, this EIP makes attacks based on jumpdest-analysis or hashing of code less problematic, so should increase the robustness of clients.
For layer 2, this EIP introduces failure-modes where there previously were none. There could exist factory-contracts which deploy multi-level contract hierarchies, such that the code for multiple contracts are included in the initcode of the first contract. The author(s) of this EIP are not aware of any such contracts.
Test Cases
Test cases should include the following cases,
CREATE
/CREATE2
/tx create
withinitcode_size
atmax_initcode_size
CREATE
/CREATE2
/tx create
withinitcode_size
atmax_initcode_size+1
Implementation
TBA
Copyright
Copyright and related rights waived via CC0.