CVE-2024-42316: mm/mglru: fix div-by-zero in vmpressure_calc_level()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-08-17 · updated 2026-06-17
Weakness: CWE-369

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().

Affected products

Linux kernel: from 6.1 before 6.1.103; from 6.2 before 6.6.44; from 6.7 before 6.10.3 — fixed in 6.1.103, 6.10.3, 6.6.44

How to fix

Upgrade to a fixed version: Linux kernel 6.1.103, 6.10.3, 6.6.44. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-42316 or the next vulnerability affects your stack