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Sanitize storing of user-supplied github context data in pre-build-checks step #7838

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Sanitize storing of user-supplied github context data in pre-build-checks step #7838

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4 changes: 2 additions & 2 deletions .github/workflows/ci-build.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -128,8 +128,8 @@ jobs:
echo "continue-build=true" >> $GITHUB_OUTPUT
else
mkdir ./dependabot-pr
echo ${{ github.head_ref }} > ./dependabot-pr/BRANCH_REF
echo ${{ github.event.pull_request.head.sha }} > ./dependabot-pr/PR_HEAD_SHA
printf '%s\n' "${{ github.head_ref }}" > ./dependabot-pr/BRANCH_REF
printf '%s\n' "${{ github.event.pull_request.head.sha }}" > ./dependabot-pr/PR_HEAD_SHA
Comment on lines -131 to +132
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@ppalaga ppalaga Oct 15, 2025

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Is this supposed to be a protection against some sort of an attack? Why is printf more safe than echo?

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@jamesnetherton jamesnetherton Oct 15, 2025

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I thought maybe to guard against being able to sneak in \ sequences that could potentially alter the output. But now that I think about it more. I don't think head_ref or sha are vulnerable to such things.

echo "$GITHUB_REF" | awk -F / '{print $3}' > ./dependabot-pr/PR_NUMBER
git diff -p --binary > ./dependabot-pr/changes.patch

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6 changes: 3 additions & 3 deletions .github/workflows/synchronize-dependabot-branch.yaml
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Expand Up @@ -80,9 +80,9 @@ jobs:
exit 1
fi

echo "branch-ref=$(cat /home/runner/work/dependabot-pr/BRANCH_REF)" >> $GITHUB_OUTPUT
echo "pr-head-sha=${PR_HEAD_SHA}" >> $GITHUB_OUTPUT
echo "pr-number=${PR_NUMBER}" >> $GITHUB_OUTPUT
echo "branch-ref=$(cat /home/runner/work/dependabot-pr/BRANCH_REF)" >> "$GITHUB_OUTPUT"
echo "pr-head-sha=${PR_HEAD_SHA}" >> "$GITHUB_OUTPUT"
echo "pr-number=${PR_NUMBER}" >> "$GITHUB_OUTPUT"
fi
- name: Checkout dependabot branch
uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
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