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Verify ZIP symlink data only after its bounds check in PureLib - #6675
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AmirMS (AmelBawa-msft) merged 2 commits intoNov 12, 2026
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AmirMS (AmelBawa-msft) merged 2 commits into
AmirMS (AmelBawa-msft) merged 2 commits into
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| if (lfh_offset > size) return PURE_E_ZIP_LFH_DATA_OVERFLOW; | ||
| // Verify symlink data only after checking that it is within the buffer: | ||
| { | ||
| int error = pure_zip_verify_symlink(&cdh, &lfh, buffer); |
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Has anyone looked at submitting this as an official patch to the upstream?
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Good question! Upstream hasn't been active since 2020, so I went with a local fix for now.
JohnMcPMS
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Nov 12, 2026
ranm-msft
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Bounds checks now run before symlink target validation. The valid-symlink and one-byte-past-end cases cover the intended behavior. Looks good.
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November 12, 2026 04:59
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📖 Description
pure_zip_metaafter the existing bounds check, so symlink data is only read once it's known to be within the buffer. Valid archives behave the same.pure.hand a "Local changes" section to the PureLib readme, so these changes are kept on future subtree updates.🔗 References
🔍 Validation
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📋 Issue Type
Microsoft Reviewers: Open in CodeFlow