Potential fix for code scanning alert no. 2: Uncontrolled command line

[cwlacewe]

Potential fix for https://github.com/IntelLabs/Video-Curation-Sample/security/code-scanning/2

In general, to fix this, we should validate and constrain the user-controlled video parameter before using it to build the ffprobe command. The path joining is already done safely, but we should additionally ensure that the video argument is a “safe” relative file name (no path separators, not empty, optionally with a required extension). That way, even though Popen is called with shell=False, we explicitly restrict what can be passed to ffprobe.

The best targeted fix without changing existing behavior is to introduce a small helper function in video/utils.py (where safely_join_path already lives) that validates the filename portion, and then use it in InfoHandler.get before passing video down to _get_info. The helper can reject values that contain path separators or are empty/whitespace. In get, we call this validator right after reading the video argument; if validation fails, we return a 400 error. The rest of the logic, including the ffprobe invocation and response format, remains unchanged.

Concretely:

• In video/utils.py, add a new function validate_video_name(name: str) -> str that:
  • Ensures name is a string.
  • Strips surrounding whitespace.
  • Rejects empty strings.
  • Rejects any name containing / or os.sep (to ensure it’s just a file name, not a path).
  • Optionally can be extended to enforce an extension, but we’ll keep it generic to avoid changing semantics.
• In video/info.py, import validate_video_name from utils, and in InfoHandler.get:
  • After decoding the argument, call validate_video_name(video) inside a try block.
  • On ValueError, respond with HTTP 400 and stop processing.
  • Otherwise, use the validated video (possibly normalized) for the existing checks and for _get_info.

This keeps the behavior for valid inputs the same, but ensures that only sanitized, well-formed file names reach the Popen command.

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