pack: bound JSON conversion depth and handle packing failures

[edsiper]

Bound shared JSON conversion before recursive descent and propagate MessagePack packing failures. This protects MQTT and inputs using a configured JSON parser, and cleans up partial output when a record cannot be converted.

Validation: Pack and JSON-parser CTest targets passed. The nesting regression fails against the original converter and passes with this change. Defensive network cases for MQTT, TCP/UDP parser and streaming modes, HTTP, Splunk and Forward passed normally and under strict Valgrind; the focused pack boundary test is Valgrind-clean.

Focused integration commands (run against the combined validation build containing these fixes):

FLUENT_BIT_BINARY=$PWD/build/bin/fluent-bit tests/integration/.venv/bin/python -m pytest tests/integration/scenarios/security_ingestors -q
VALGRIND=1 VALGRIND_STRICT=1 FLUENT_BIT_BINARY=$PWD/build/bin/fluent-bit tests/integration/.venv/bin/python -m pytest tests/integration/scenarios/security_ingestors -q

Relevant internal CTest targets and focused Valgrind checks also passed. Full PR-range commit-prefix lint, DCO and whitespace checks passed against fetched master. Code and regression tests are separate commits.

Compatibility: JSON containers beyond the configured MessagePack nesting budget (64 in this build) are rejected. Configured parser inputs retain their existing fallback behavior. Public interfaces are unchanged.

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of deeply nested JSON and MessagePack payloads by safely limiting nesting depth.
  • Prevented ingestion failures and process instability when malformed or excessively nested records are received.
  • Added safeguards against oversized inputs that could cause length-calculation errors.
  • Improved error handling during JSON-to-MessagePack conversion so failed conversions clean up safely and report an error.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: c7ea8ca7-ddb0-492d-a687-443c21f02f47

📥 Commits

Reviewing files that changed from the base of the PR and between a48daa6 and 2c8bf0a.

📒 Files selected for processing (3)

• src/flb_pack.c
• tests/integration/scenarios/security_ingestors/tests/test_security_ingestors.py
• tests/internal/pack.c

Included review availability: Your plan provides up to 8 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

The YYJSON-to-MessagePack path now limits nesting, propagates packing failures, prevents allocation-size overflow, and cleans up errors. Unit and integration tests cover depth limits and recovery across network ingestion protocols.

Changes

YYJSON nesting and recovery

Layer / File(s)	Summary
Conversion depth and error handling src/flb_pack.c	yyjson_val_to_msgpack returns errors, limits container depth, and checks MessagePack packing calls. Input length validation prevents allocation overflow. Failed conversions release allocated resources.
Unit coverage for depth limits tests/internal/pack.c	Tests cover map, array, and mixed nesting at and above MSGPACK_EMBED_STACK_SIZE.
Network ingestion recovery coverage tests/integration/scenarios/security_ingestors/tests/test_security_ingestors.py	Integration tests send deeply nested records through multiple protocols and verify that Fluent Bit remains running and shuts down cleanly.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~30 minutes

Change: Bug fix

Suggested reviewers: cosmo0920

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main changes: limiting JSON conversion depth and handling MessagePack packing failures.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 2

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🛠️ Fix failing CI checks 💡

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🧪 Generate unit tests (beta)

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-19T15:36:38.358159Z	2c8bf0a	Draft marked ready

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 2c8bf0a15d

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[chatgpt-codex-connector]

Honor macOS Leaks mode in the new daemon

When this scenario runs on macOS via run_tests.py --leaks-strict, the runner sets LEAKS and LEAKS_STRICT, but this condition remains false and launches Fluent Bit directly. Consequently, the required memory-safety pass can report success without running Leaks or checking its result; handle LEAKS here or use the suite's existing memory-check wrapper.

AGENTS.md reference: AGENTS.md:L101-L105

Useful? React with 👍 / 👎.

[UgurTheG]

High likely a duplicate of #12313