[PR #1807] fix(lib_ccx): replace unsafe string functions with bounds-checked versions #2548

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claunia · 2026-01-29T17:22:43Z

claunia commented

2026-01-29 17:22:43 +00:00

Original Pull Request: https://github.com/CCExtractor/ccextractor/pull/1807

State: closed
Merged: Yes

Summary

Replace sprintf/strcpy/strcat with bounds-checked versions in files identified in Phase 3.1 of the buffer safety audit. This completes all dangerous function pattern fixes.

Files Modified

Medium Priority (previous commit)

File	Changes
ccx_encoders_common.c	4 sprintf → snprintf
ccx_encoders_helpers.c	3 strcat → strncat, 1 strcpy → memcpy
telxcc.c	3 sprintf → snprintf
asf_functions.c	3 sprintf → snprintf
ccx_encoders_ssa.c	3 sprintf → snprintf
ccx_encoders_curl.c	1 sprintf → snprintf, strcpy+strcat → snprintf with OOM check
ccx_encoders_splitbysentence.c	1 strcpy → memmove (overlapping memory fix), 2 strcat → strncat

Low Priority (latest commit)

File	Changes
general_loop.c	Proper buffer allocation with OOM check, snprintf
ccx_encoders_g608.c	snprintf with sizeof for timeline buffer
lib_ccx.c	Fix buffer size calculation (was 2 bytes short), add missing null check, snprintf
ccx_common_timing.c	snprintf with documented max size for time functions
ts_functions.c	snprintf with sizeof in debug code
matroska.c	Bounded memcpy to prevent overflow from malformed language codes
output.c	snprintf with known allocated size

Notable Fixes

ccx_encoders_splitbysentence.c: Fixed undefined behavior where strcpy() was used with overlapping memory regions. Replaced with memmove().
ccx_encoders_curl.c: Added OOM check for malloc allocation that was previously unchecked.
lib_ccx.c: Fixed buffer size calculation - was allocating strlen + 10 but needed strlen + 12 for the format string.
matroska.c: Protected against malformed language codes that could cause buffer overflow from untrusted file input.

Test plan

Builds successfully on Linux
CI tests pass

🤖 Generated with Claude Code

**Original Pull Request:** https://github.com/CCExtractor/ccextractor/pull/1807 **State:** closed **Merged:** Yes --- ## Summary Replace sprintf/strcpy/strcat with bounds-checked versions in files identified in Phase 3.1 of the buffer safety audit. This completes all dangerous function pattern fixes. ### Files Modified #### Medium Priority (previous commit) | File | Changes | |------|---------| | ccx_encoders_common.c | 4 sprintf → snprintf | | ccx_encoders_helpers.c | 3 strcat → strncat, 1 strcpy → memcpy | | telxcc.c | 3 sprintf → snprintf | | asf_functions.c | 3 sprintf → snprintf | | ccx_encoders_ssa.c | 3 sprintf → snprintf | | ccx_encoders_curl.c | 1 sprintf → snprintf, strcpy+strcat → snprintf with OOM check | | ccx_encoders_splitbysentence.c | 1 strcpy → memmove (overlapping memory fix), 2 strcat → strncat | #### Low Priority (latest commit) | File | Changes | |------|---------| | general_loop.c | Proper buffer allocation with OOM check, snprintf | | ccx_encoders_g608.c | snprintf with sizeof for timeline buffer | | lib_ccx.c | Fix buffer size calculation (was 2 bytes short), add missing null check, snprintf | | ccx_common_timing.c | snprintf with documented max size for time functions | | ts_functions.c | snprintf with sizeof in debug code | | matroska.c | Bounded memcpy to prevent overflow from malformed language codes | | output.c | snprintf with known allocated size | ### Notable Fixes 1. **ccx_encoders_splitbysentence.c**: Fixed undefined behavior where `strcpy()` was used with overlapping memory regions. Replaced with `memmove()`. 2. **ccx_encoders_curl.c**: Added OOM check for malloc allocation that was previously unchecked. 3. **lib_ccx.c**: Fixed buffer size calculation - was allocating `strlen + 10` but needed `strlen + 12` for the format string. 4. **matroska.c**: Protected against malformed language codes that could cause buffer overflow from untrusted file input. ## Test plan - [x] Builds successfully on Linux - [ ] CI tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code)

claunia added the pull-request label 2026-01-29 17:22:43 +00:00

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Reference: starred/ccextractor#2548