Guard against artifact poisoning in commenter#10149
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Potential fix for [https://github.com/microsoft/typespec/security/code-scanning/107](https://github.com/microsoft/typespec/security/code-scanning/107) In general, to prevent artifact poisoning you should never let downloaded artifacts overwrite files in the repository workspace, and you should treat their contents as untrusted: extract them into a dedicated temporary directory and only read specific expected files from there, validating them if necessary. You should also avoid running build tools or package managers (`npm install`, `pnpm install`, etc.) in a workspace that may have been modified by untrusted artifact contents. For this specific workflow, the best minimal fix is: 1. Create a temporary directory under `${{ runner.temp }}` to hold the downloaded artifact. 2. Change the `actions/download-artifact@v4` step to use `path: ${{ runner.temp }}/comment-artifact` (or similar) so that artifact contents cannot overwrite the repository’s code or config. 3. Adjust the later use of `comment.json` to point at that safe location (e.g., `--comment-file ${{ runner.temp }}/comment-artifact/comment.json`). 4. Leave `pnpm install` as-is, since once the artifact is isolated from the workspace, it can no longer affect what `pnpm install` reads or executes. All changes occur in `.github/workflows/commenter.yml`: - Add a shell step before `actions/download-artifact@v4` to `mkdir -p ${{ runner.temp }}/comment-artifact`. - Modify the `download-artifact` step to include `path: ${{ runner.temp }}/comment-artifact`. - Modify the `pnpm chronus-github-pr-commenter` step to read the comment file from that temp directory. No extra actions or external libraries are required. _Suggested fixes powered by Copilot Autofix. Review carefully before merging._ Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
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Potential fix for https://github.com/microsoft/typespec/security/code-scanning/107
In general, to prevent artifact poisoning you should never let downloaded artifacts overwrite files in the repository workspace, and you should treat their contents as untrusted: extract them into a dedicated temporary directory and only read specific expected files from there, validating them if necessary. You should also avoid running build tools or package managers (
npm install,pnpm install, etc.) in a workspace that may have been modified by untrusted artifact contents.For this specific workflow, the best minimal fix is:
${{ runner.temp }}to hold the downloaded artifact.actions/download-artifact@v4step to usepath: ${{ runner.temp }}/comment-artifact(or similar) so that artifact contents cannot overwrite the repository’s code or config.comment.jsonto point at that safe location (e.g.,--comment-file ${{ runner.temp }}/comment-artifact/comment.json).pnpm installas-is, since once the artifact is isolated from the workspace, it can no longer affect whatpnpm installreads or executes.All changes occur in
.github/workflows/commenter.yml:actions/download-artifact@v4tomkdir -p ${{ runner.temp }}/comment-artifact.download-artifactstep to includepath: ${{ runner.temp }}/comment-artifact.pnpm chronus-github-pr-commenterstep to read the comment file from that temp directory.No extra actions or external libraries are required.
Suggested fixes powered by Copilot Autofix. Review carefully before merging.