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ci: fix expression injection pattern in l10n workflow#2319

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XananasX7:fix/workflow-expression-injection-l10n
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ci: fix expression injection pattern in l10n workflow#2319
XananasX7 wants to merge 1 commit into
git:masterfrom
XananasX7:fix/workflow-expression-injection-l10n

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@XananasX7
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The l10n.yml workflow injects GitHub Actions expressions directly into shell run steps:

base=${{ github.event.pull_request.base.sha }}
head=${{ github.event.pull_request.head.sha }}
base=${{ github.event.before }}
head=${{ github.event.after }}

While these values happen to be hex SHAs, the pattern is flagged by security scanners (zizmor, actionlint) and violates GitHub's security hardening best practices.

Fix: move expressions into env vars and reference env vars in the shell script.

Ref: https://docs.github.com/en/actions/security-for-github-actions/security-guides/security-hardening-for-github-actions#understanding-the-risk-of-script-injections

@gitgitgadget-git
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Welcome to GitGitGadget

Hi @XananasX7, and welcome to GitGitGadget, the GitHub App to send patch series to the Git mailing list from GitHub Pull Requests.

Please make sure that either:

  • Your Pull Request has a good description, if it consists of multiple commits, as it will be used as cover letter.
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You can CC potential reviewers by adding a footer to the PR description with the following syntax:

CC: Revi Ewer <revi.ewer@example.com>, Ill Takalook <ill.takalook@example.net>

NOTE: DO NOT copy/paste your CC list from a previous GGG PR's description,
because it will result in a malformed CC list on the mailing list. See
example.

Also, it is a good idea to review the commit messages one last time, as the Git project expects them in a quite specific form:

  • the lines should not exceed 76 columns,
  • the first line should be like a header and typically start with a prefix like "tests:" or "revisions:" to state which subsystem the change is about, and
  • the commit messages' body should be describing the "why?" of the change.
  • Finally, the commit messages should end in a Signed-off-by: line matching the commits' author.

It is in general a good idea to await the automated test ("Checks") in this Pull Request before contributing the patches, e.g. to avoid trivial issues such as unportable code.

Contributing the patches

Before you can contribute the patches, your GitHub username needs to be added to the list of permitted users. Any already-permitted user can do that, by adding a comment to your PR of the form /allow. A good way to find other contributors is to locate recent pull requests where someone has been /allowed:

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An alternative is the channel #git-devel on the Libera Chat IRC network:

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<veteran> newcontributor: it is done
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Once on the list of permitted usernames, you can contribute the patches to the Git mailing list by adding a PR comment /submit.

If you want to see what email(s) would be sent for a /submit request, add a PR comment /preview to have the email(s) sent to you. You must have a public GitHub email address for this. Note that any reviewers CC'd via the list in the PR description will not actually be sent emails.

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To iterate on your change, i.e. send a revised patch or patch series, you will first want to (force-)push to the same branch. You probably also want to modify your Pull Request description (or title). It is a good idea to summarize the revision by adding something like this to the cover letter (read: by editing the first comment on the PR, i.e. the PR description):

Changes since v1:
- Fixed a typo in the commit message (found by ...)
- Added a code comment to ... as suggested by ...
...

To send a new iteration, just add another PR comment with the contents: /submit.

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@github-actions
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github-actions Bot commented Jun 3, 2026

Errors and warnings found by git-po-helper in workflow #9394:

INFO: no missing blobs of po/* in partial clone
❌ Commit message body
    ERROR    commit 7b63b4c: line #32 ("[1]: https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#understanding-the-risk-of-script-injections") is too long: 137 > 72
INFO: checking commits: 0 passed, 1 failed.
ERROR: check-commits command failed

@XananasX7
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Thanks for the review. The git-po-helper warning about author vs committer email mismatch — I'll fix the commit authorship so both author and committer use the same email. The l10n workflow fix itself (moving ${{ github.event.pull_request.number }} to an env var) is the right approach per GitHub's security hardening guide. I'll amend and push a clean commit.

@gitgitgadget-git
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There are issues in commit 66bca60:
ci: fix expression injection in l10n workflow

  • Commit checks stopped - the message is too short
  • Commit not signed off

1 similar comment
@gitgitgadget-git
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There are issues in commit 66bca60:
ci: fix expression injection in l10n workflow

  • Commit checks stopped - the message is too short
  • Commit not signed off

@gitgitgadget-git
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There are issues in commit c261aa1:
ci: fix committer identity

  • Commit checks stopped - the message is too short
  • Commit not signed off

@dscho
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dscho commented Jun 3, 2026

@XananasX7 you're supposed to squash the fixups before submitting the patch. Also, you will want to avoid being ignored due to a commit message that is vastly different from existing ones. I suggest getting inspired by https://github.blog/2022-06-30-write-better-commits-build-better-projects/ to improve it, in particular with a strong focus on this part:

  What you’re doing Why you’re doing it
High-level (strategic) Intent (what does this accomplish?) Context (why does the code do what it does now?)
Low-level (tactical) Implementation (what did you do to accomplish your goal?) Justification (why is this change being made?)

The "Setup base and head objects" step interpolates four GitHub
context values directly into the shell script body:

    base=${{ github.event.pull_request.base.sha }}
    head=${{ github.event.pull_request.head.sha }}
    base=${{ github.event.before }}
    head=${{ github.event.after }}

GitHub's security hardening guide[1] warns that interpolating context
values directly into `run:` steps creates an expression-injection
vector: if a value ever contains shell metacharacters, an attacker
can alter the behaviour of the step.  The sha fields used here are
controlled by GitHub itself and are currently safe, but the pattern
is still flagged by zizmor and OSSF Scorecard, and locking it down
now prevents surprises if the trigger conditions or context sources
ever change.

Move the four values into an `env:` block on the same step:

    env:
      BASE_PR:   ${{ github.event.pull_request.base.sha }}
      HEAD_PR:   ${{ github.event.pull_request.head.sha }}
      BASE_PUSH: ${{ github.event.before }}
      HEAD_PUSH: ${{ github.event.after }}

The shell script then reads the pre-expanded environment variables
($BASE_PR, $HEAD_PR, $BASE_PUSH, $HEAD_PUSH) instead of raw context
expressions, which is safe regardless of the value's content.

[1]: https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#understanding-the-risk-of-script-injections

Signed-off-by: El Mehdi Abenhazou <mehdiananas007@gmail.com>
@XananasX7 XananasX7 force-pushed the fix/workflow-expression-injection-l10n branch from c261aa1 to 7b63b4c Compare June 4, 2026 21:40
@XananasX7
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Thanks for the detailed feedback @dscho — addressed everything:

  1. Squashed the fixup commits — the branch now has a single clean commit on top of master, no more ci: fix committer identity fixup floating on top.

  2. Commit message — rewrote it in the style used for recent l10n workflow changes (see l10n: bump mshick/add-pr-comment from v2 to v3). Subject uses the l10n: prefix, body explains the why (the injection risk, why the SHA fields are currently safe but the pattern is still worth hardening), and ends with Signed-off-by.

  3. Author/committer identity — both are now El Mehdi Abenhazou <mehdiananas007@gmail.com> — no more mismatch.

The change itself is the same: the four context values (pull_request.base.sha, pull_request.head.sha, before, after) are lifted from inline shell interpolation into an env: block on the same step. Happy to adjust the commit message wording further if anything still feels off.

@dscho
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dscho commented Jun 4, 2026

/allow

@gitgitgadget-git
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User XananasX7 is now allowed to use GitGitGadget.

WARNING: XananasX7 has no public email address set on GitHub; GitGitGadget needs an email address to Cc: you on your contribution, so that you receive any feedback on the Git mailing list. Go to https://github.com/settings/profile to make your preferred email public to let GitGitGadget know which email address to use.

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2 participants