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Vulnerability CVE-2024-42316
Published: 2024-08-17
| Description: |
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(). |
References: |
https://git.kernel.org/stable/c/8de7bf77f21068a5f602bb1e59adbc5ab533509d
https://git.kernel.org/stable/c/d6510f234c7d117790397f9bb150816b0a954a04
https://git.kernel.org/stable/c/a39e38be632f0e1c908d70d1c9cd071c03faf895
https://git.kernel.org/stable/c/8b671fe1a879923ecfb72dda6caf01460dd885ef
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