[PR #1817] [MERGED] fix(rust): Add bounds checks to prevent panic on malformed CEA-708 data #2561

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claunia · 2026-01-29T17:22:47Z

claunia commented

2026-01-29 17:22:47 +00:00

📋 Pull Request Information

Original PR: https://github.com/CCExtractor/ccextractor/pull/1817
Author: @cfsmp3
Created: 12/14/2025
Status: ✅ Merged
Merged: 12/14/2025
Merged by: @cfsmp3

Base: master ← Head: fix/issue-1616-mp4-hls-crash

📝 Commits (2)

e852057 fix(rust): Add bounds checks to prevent panic on malformed CEA-708 data
633d844 fix(rust): cast c_long to i64 in pic.rs for Windows compatibility

📊 Changes

2 files changed (+100 additions, -3 deletions)

View changed files

📝 src/rust/src/decoder/service_decoder.rs (+95 -2)
📝 src/rust/src/es/pic.rs (+5 -1)

📄 Description

Summary

Fixes #1616 - Segmentation fault when extracting from MP4 remuxed from HLS
Fixes #1575 - Regression bug causing ccextractor 0.94 to crash

The CEA-708 decoder could panic when processing truncated or malformed caption data blocks. This PR adds proper bounds checking to prevent panics:

Fixed EXT1 command handling in process_service_block():
- Changed &block[1..] to &block[(i+1)..] for correct slice offset when EXT1 appears at non-zero positions
- Added bounds check before accessing the next byte after EXT1
Added bounds checks in handle_extended_char():
- Check for empty block before accessing block[0]
- Check block.len() >= 2 before accessing block[1] for C3 commands
Fixed clippy warning in es/pic.rs:
- Removed unnecessary as i64 cast

Test plan

Verified with #1616 sample file (MP4 remuxed from HLS)
Verified with #1575 sample file (EIA-608 and EIA-708 streams.ts) - extracts subtitles correctly
All 268 Rust tests pass
Added 4 new unit tests for bounds checking:
- test_handle_extended_char_empty_block
- test_handle_extended_char_c3_insufficient_bytes
- test_process_service_block_ext1_at_end
- test_process_service_block_ext1_with_truncated_c3
No clippy warnings
No formatting issues

🤖 Generated with Claude Code

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/CCExtractor/ccextractor/pull/1817 **Author:** [@cfsmp3](https://github.com/cfsmp3) **Created:** 12/14/2025 **Status:** ✅ Merged **Merged:** 12/14/2025 **Merged by:** [@cfsmp3](https://github.com/cfsmp3) **Base:** `master` ← **Head:** `fix/issue-1616-mp4-hls-crash` --- ### 📝 Commits (2) - [`e852057`](https://github.com/CCExtractor/ccextractor/commit/e852057a9433a4b093b8c390165b90e4f97b0c64) fix(rust): Add bounds checks to prevent panic on malformed CEA-708 data - [`633d844`](https://github.com/CCExtractor/ccextractor/commit/633d84462f3bbcac0ebf1224b67be99d4c477733) fix(rust): cast c_long to i64 in pic.rs for Windows compatibility ### 📊 Changes **2 files changed** (+100 additions, -3 deletions) <details> <summary>View changed files</summary> 📝 `src/rust/src/decoder/service_decoder.rs` (+95 -2) 📝 `src/rust/src/es/pic.rs` (+5 -1) </details> ### 📄 Description ## Summary Fixes #1616 - Segmentation fault when extracting from MP4 remuxed from HLS Fixes #1575 - Regression bug causing ccextractor 0.94 to crash The CEA-708 decoder could panic when processing truncated or malformed caption data blocks. This PR adds proper bounds checking to prevent panics: - **Fixed EXT1 command handling** in `process_service_block()`: - Changed `&block[1..]` to `&block[(i+1)..]` for correct slice offset when EXT1 appears at non-zero positions - Added bounds check before accessing the next byte after EXT1 - **Added bounds checks** in `handle_extended_char()`: - Check for empty block before accessing `block[0]` - Check `block.len() >= 2` before accessing `block[1]` for C3 commands - **Fixed clippy warning** in `es/pic.rs`: - Removed unnecessary `as i64` cast ## Test plan - [x] Verified with #1616 sample file (MP4 remuxed from HLS) - [x] Verified with #1575 sample file (EIA-608 and EIA-708 streams.ts) - extracts subtitles correctly - [x] All 268 Rust tests pass - [x] Added 4 new unit tests for bounds checking: - `test_handle_extended_char_empty_block` - `test_handle_extended_char_c3_insufficient_bytes` - `test_process_service_block_ext1_at_end` - `test_process_service_block_ext1_with_truncated_c3` - [x] No clippy warnings - [x] No formatting issues 🤖 Generated with [Claude Code](https://claude.com/claude-code) --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

claunia added the pull-request label 2026-01-29 17:22:47 +00:00

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Reference: starred/ccextractor#2561