Memory Allocation overflow on abi.decode()

[pscott]

Component

Forge

Have you ensured that all of these are up to date?

• Foundry
• Foundryup

What version of Foundry are you on?

forge 0.2.0 (b44b045 2023-02-21T00:22:41.521901Z)

What command(s) is the bug in?

forge test --optimize --vv

Operating System

macOS (Apple Silicon)

Describe the bug

I’m getting the error [FAIL. Reason: Memory allocation overflow] on one of my tests.
it happens when I run abi.decode() like so:

// Structre of `Indexed Strategy`
struct IndexedStrategy {
  uint8 i;
  bytes b;
};

...

// Actual code that fails
(
    address v,
    uint256 id,
    Choice choice,
    IndexedStrategy[] memory uvs,
    string memory reason
) = abi.decode(data, (address, uint256, Choice, IndexedStrategy[], string));

This code works just fine if I remove reason. It also works just fine if I remove uvs and keep reason.
I get the same error if I interchange reason and put it between id and choice (I thought maybe it had to do with two dynamic args being next to each other).

[mattsse]

this is an evm panic ref https://soliditydeveloper.com/solidity-0.8 0x41
can you try after increasing the memory_limit

forge config | grep memory                                                                                                                                                                                                                 
memory_limit = 33554432

not sure if that's exposed in cli, if not we should

[pscott]

this is an evm panic ref https://soliditydeveloper.com/solidity-0.8 0x41 can you try after increasing the memory_limit

forge config | grep memory                                                                                                                                                                                                                 
memory_limit = 33554432

not sure if that's exposed in cli, if not we should

Cheers. Indeed

➜  tmp git:(main) ✗ forge config | rg memory         
memory_limit = 33554432

Haven't found a way to increase the memory limit via CLI.
Also I'm not sure why this would trigger 0x41: my IndexedStrategy array holds 1 element and reason is set to "".. 🤔

[mattsse]

unfamiliar with the internals but Memory allocation overflow is the mapped error for the evm panic with 0x41

[pscott]

Updated the foundry.toml profile.default config to and added memory_limit = 67108864 (x2 default value).
Got the same error. Any idea what I should look into?

[mattsse]

can you try with something ridiculous like 1GB?

@rakita Under what circumstances is the memory limit in the evm actually violated?

[pscott]

memory_limit = 1000000000 still fails.
I wonder if memory_limit is actually taken into account because I have no way of knowing whether the memory limit actually is 1GB or the default one

[mattsse]

hmm, perhaps this is actually unrelated to the revm env setting @rakita?

[rakita]

can you try with something ridiculous like 1GB?

@rakita Under what circumstances is the memory limit in the evm actually violated?

Do you mean this: https://github.com/bluealloy/revm/blob/main/crates/primitives/Cargo.toml#L60
It is memory inside Interpreter, when there is for example MSTORE that wants to write to the memory location with offset of 20gb, this would trigger.

[mattsse]

this error is decoded from a revert/panic here

foundry/evm/src/decode.rs

Lines 117 to 118 in 13c1cf7

	// allocating too much memory or creating too large array
	Ok("Memory allocation overflow".to_string())

for

// allocating too much memory or creating too large array

is this unrelated to the memory_limit setting?

[pscott]

Nvm.. this error actually gets thrown when you try to decode something invalid (in my case, I forgot to add the last argument when ENCODING, so decoding was failing).

Would have expected another error to pop, not a weird memory overflow error but.. such is life.

sorry for wasting your time :(

[mattsse]

nice!

good to know, thanks for sharing