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CVE-2024-40950mm: huge_memory: fix misused mapping_large_folio_support() for anon folios

Description

In the Linux kernel, the following vulnerability has been resolved: mm: huge_memory: fix misused mapping_large_folio_support() for anon folios When I did a large folios split test, a WARNING "[ 5059.122759][ T166] Cannot split file folio to non-0 order" was triggered. But the test cases are only for anonmous folios. while mapping_large_folio_support() is only reasonable for page cache folios. In split_huge_page_to_list_to_order(), the folio passed to mapping_large_folio_support() maybe anonmous folio. The folio_test_anon() check is missing. So the split of the anonmous THP is failed. This is also the same for shmem_mapping(). We'd better add a check for both. But the shmem_mapping() in __split_huge_page() is not involved, as for anonmous folios, the end parameter is set to -1, so (head[i].index >= end) is always false. shmem_mapping() is not called. Also add a VM_WARN_ON_ONCE() in mapping_large_folio_support() for anon mapping, So we can detect the wrong use more easily. THP folios maybe exist in the pagecache even the file system doesn't support large folio, it is because when CONFIG_TRANSPARENT_HUGEPAGE is enabled, khugepaged will try to collapse read-only file-backed pages to THP. But the mapping does not actually support multi order large folios properly. Using /sys/kernel/debug/split_huge_pages to verify this, with this patch, large anon THP is successfully split and the warning is ceased.

Timeline

  1. ID reserved

    By Linux

  2. Published

  3. · 22 months later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2024-40950, by who scored it
Scored byCVSSScoreVector
NVDNVD · Analyzed3.1Medium5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.21% · top 89% of all CVEs (12 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Affected products

  • Linux · Linux

    • affected c010d47f107f609b9f4d6a103b6dfc53889049e9 – < 5df493a99fcf887133cf01d23cd4bebb6d385d3c
    • affected c010d47f107f609b9f4d6a103b6dfc53889049e9 – < 6a50c9b512f7734bc356f4bd47885a6f7c98491a

  • Linux · Linux

    • affected 6.9
    • unaffected < 6.9
    • unaffected 6.9.7 – ≤ 6.9.*
    • unaffected 6.10 – ≤ *

References

References2

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .