CVE-2024-42316: mm/mglru: fix div-by-zero in vmpressure_calc_level()
First published: Sat Aug 17 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: mm/mglru: fix div-by-zero in vmpressure_calc_level() evict_folios() uses a second pass to reclaim folios that have gone through page writeback and become clean before it finishes the first pass, since folio_rotate_reclaimable() cannot handle those folios due to the isolation. The second pass tries to avoid potential double counting by deducting scan_control->nr_scanned. However, this can result in underflow of nr_scanned, under a condition where shrink_folio_list() does not increment nr_scanned, i.e., when folio_trylock() fails. The underflow can cause the divisor, i.e., scale=scanned+reclaimed in vmpressure_calc_level(), to become zero, resulting in the following crash: [exception RIP: vmpressure_work_fn+101] process_one_work at ffffffffa3313f2b Since scan_control->nr_scanned has no established semantics, the potential double counting has minimal risks. Therefore, fix the problem by not deducting scan_control->nr_scanned in evict_folios().
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=6.1<6.1.103 | |
| Linux Linux kernel | >=6.2<6.6.44 | |
| Linux Linux kernel | >=6.7<6.10.3 | |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.119-1 6.11.10-1 6.12.5-1 |
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Reference Links
- https://git.kernel.org/stable/c/8b671fe1a879923ecfb72dda6caf01460dd885ef
- https://git.kernel.org/stable/c/8de7bf77f21068a5f602bb1e59adbc5ab533509d
- https://git.kernel.org/stable/c/a39e38be632f0e1c908d70d1c9cd071c03faf895
- https://git.kernel.org/stable/c/d6510f234c7d117790397f9bb150816b0a954a04
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-42316
- https://nvd.nist.gov/vuln/detail/CVE-2024-42316
- https://launchpad.net/bugs/cve/CVE-2024-42316
- https://security-tracker.debian.org/tracker/CVE-2024-42316
- https://ubuntu.com/security/CVE-2024-42316
- https://git.kernel.org/linus/8b671fe1a879923ecfb72dda6caf01460dd885ef
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