fix: limit Vec::with_capacity in binary calldata decoder to prevent OOM

[lau90eth]

Summary

Adds a maximum capacity guard in the binary calldata decoder to prevent OOM allocation via malicious input.

Root Cause

In executor/crates/calldata/src/bin.rs:214, Vec::with_capacity(full_size) is called where full_size comes directly from untrusted wire data with no upper bound check:

stack.push(Frame::Array {
    collected: Vec::with_capacity(full_size), // OOM if full_size is huge
    remaining: full_size,
});

A malicious calldata packet can set the array size field to a large value (e.g. 0xFFFFFFFF), causing the allocator to attempt a multi-GB allocation and crash the validator process.

Impact

Validator OOM crash — consensus liveness compromised. Introduced in commit 699ec88 (feat: add limit to calldata parsing) which rewrote the decoder in bin.rs without carrying over the original bounds check from de.rs.

Fix

Added MAX_ARRAY_CAPACITY = 1024 * 1024 guard before Vec::with_capacity, returning an error for oversized arrays.

PoC

https://github.com/lau90eth/genvm-bin-oom

Related

Finding originally submitted to GenLayer Builders Program portal.

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📥 Commits

Reviewing files that changed from the base of the PR and between abb71bf and 32dc8e7.

📒 Files selected for processing (2)

• executor/crates/calldata/src/bin.rs
• executor/src/wasi/genlayer_sdk.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

👋 This PR targeted main, so I've retargeted it to the latest dev branch v0.3-dev.

main is protected and is only an alias of the latest release branch (v0.3-dev), kept in lockstep automatically. Active v0.3 work lands on v0.3-dev, which reaches v0.3.x through the standing release-gate PR once the cross-repo E2E matrix is green.