[codex] Fix oversized video inputs in multimodal loader

[InfoSage05]

Title

Fix segfault on oversized file:// video inputs in multimodal pipeline and this is in response to the bug #46589

Summary

This change adds a configurable video size guard so local or downloaded videos are rejected before they are passed into FFmpeg/PyAV. It is intended to prevent server-wide crashes when large file:// MP4 inputs are sent to Qwen3.5-VL style multimodal models.

What changed

• Added --max-video-size-mb as a multimodal CLI/config option.
• Threaded that limit through EngineArgs -> ModelConfig -> media_io_kwargs.
• Added validation in VideoMediaIO so oversized inputs fail with a clean ValueError.
• Wrapped the FFmpeg-backed video load paths in VideoBackend so normal decode errors become Python exceptions.
• Added regression tests for:
  • oversized raw video bytes,
  • oversized local file:// video paths,
  • CLI parsing of --max-video-size-mb.

Files touched

• vllm/multimodal/media/video.py
• vllm/multimodal/video.py
• vllm/config/model.py
• vllm/engine/arg_utils.py
• tests/multimodal/media/test_video.py
• tests/multimodal/media/test_connector.py
• tests/engine/test_arg_utils.py

Notes

• This does not fully sandbox native FFmpeg segfaults. Python cannot catch a true C-level crash in-process.
• The size check is the practical mitigation for the reported >2GB file:// crash path.

Validation

• python3 -m py_compile passed for all touched files.
• Full pytest execution could not be run in this environment because the local venv is missing pytest and torch.

[claude]

Claude Code Review

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[mergify]

Documentation preview: https://vllm--46836.org.readthedocs.build/en/46836/

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @InfoSage05.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[InfoSage05]

I could not complete a local git fetch/rebase from this environment because github.com DNS resolution is blocked here, so
the PR still shows as non-mergeable on GitHub @mergify

[jashwanth-reddy-g]

Thanks for the PR. This is a very important safeguard to have. However, there are a few critical issues in how the CLI arguments were added in vllm/engine/arg_utils.py that will cause regressions.

1. Incorrect add_argument for --max-video-size-mb
   In vllm/engine/arg_utils.py, you have added:

multimodal_group.add_argument(
    "--max-video-size-mb",
    "--mm-processor-kwargs", **multimodal_kwargs["mm_processor_kwargs"]
)

This aliases --max-video-size-mb and --mm-processor-kwargs together. As a result:

• The argument's destination (dest) resolves to max_video_size_mb, completely hijacking --mm-processor-kwargs.
• Any users who pass --mm-processor-kwargs will have their inputs parsed into args.max_video_size_mb instead, causing unexpected errors.
• You didn't actually add the kwargs/help for --max-video-size-mb properly.

2. Accidental modification of --shutdown-timeout
   Further down in vllm/engine/arg_utils.py, it appears a copy-paste error occurred where the help text and default value intended for --max-video-size-mb were applied to --shutdown-timeout:

parser.add_argument(
    "--shutdown-timeout",
    type=int,
    default=None,
    help="Maximum allowed video file size in MiB before decoding. "
    "Set to 0 to disable the check.",
)

This breaks --shutdown-timeout (it used to default to 0 and had its own help message).

Could you please fix these argparse definitions?

• Create a distinct multimodal_group.add_argument("--max-video-size-mb", ...) with the correct help string.
• Restore --mm-processor-kwargs and --shutdown-timeout to their original definitions.

Let me know if you have any questions!

[InfoSage05]

Thank you for the careful review. I have corrected the argparse definitions so that --max-video-size-mb is now a standalone multimodal option, --mm-processor-kwargs retains its original definition, and --shutdown-timeout has been restored to its original default and help text. Please take another look at the latest commit.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @InfoSage05.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @InfoSage05.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[InfoSage05]

@hmellor Added max_video_size_mb to MultiModalConfig so the CLI arg now uses multimodal_kwargs like all other args, and default comes from ModelConfig.max_video_size_mb like all other EngineArgs attributes.
Thank you for reviewing the code.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @InfoSage05.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork