fix: adding length validation on deserialization

[mrzeszutko]

Summary

Add semantic validation to P2P message deserialization to reject protocol-violating array/string lengths. This prevents DoS attacks via maliciously crafted messages that specify enormous sizes, which could cause memory exhaustion before the buffer range check catches the issue.

Changes

Foundation Layer

• BufferReader: Added optional maxSize parameter to readVector(), readBuffer(), and readString() methods. This is a non-breaking change - all 161+ existing calls continue to work unchanged.

Constants Organization

• stdlib/deserialization: New module with shared constants:

  • MAX_TXS_PER_BLOCK = 2 ** 16 (65536)
  • MAX_COMMITTEE_SIZE = 2,048 (theoretical max from bitmap design: 256 bytes × 8 bits)
  • MAX_BLOCKS_PER_CHECKPOINT = 72
  • MAX_TX_EFFECTS_PER_BODY = BLOBS_PER_CHECKPOINT * FIELDS_PER_BLOB
  • MAX_BLOCK_HASH_STRING_LENGTH = 128

• p2p/reqresp/constants: P2P-specific constants:

  • MAX_VERSION_STRING_LENGTH = 64
  • MAX_BLOCK_HASH_STRING_LENGTH = 128
  • Re-exports MAX_TXS_PER_BLOCK from stdlib

Bounds Checking Added To

File	Validation Added
BlockProposal.fromBuffer	txHashes, txs arrays
Checkpoint.fromBuffer	blocks vector
PublishedCheckpoint.fromBuffer	attestations, l1BlockHash
Body.fromBuffer	txEffects vector
CheckpointedL2Block.fromBuffer	attestations, l1BlockHash
PublishedL2Block.fromBuffer	attestations, l1BlockHash
deserializeValidateBlockResult	committee, attestors, attestations, reason string
StatusMessage.fromBuffer	version string, block hash
BitVector.fromBuffer	length field

Tests

• Added 9 new tests for BufferReader maxSize bounds checking
• Added 2 tests for BitVector bounds validation

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Fixes A-273

[PhilWindle]

Looks good. Just one thing we need to check.

[PhilWindle]

Can we just check this? This version isn't a semver (i.e. 1.2.3-alpha.123). It's our compressed components version which incorporates a number of items. Can you verify that MAX_VERSION_STRING_LENGTH is sufficient for this?

[PhilWindle]

Here is an example:

p2p:7:libp2p_service:libp2p_service Started libp2p service with protocol version 00-31337-00000000-0-14d6d44e-01eff751

[PhilWindle]

I think we should be fine as MAX_VERSION_STRING_LENGTH is 64, but would like to check.