CVE-2026-31466mm/huge_memory: fix folio isn't locked in softleaf_to_folio()
- 4.7MediumCVSS base score
- 0.09%Exploitation in 30 daysEPSS · top 99% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix folio isn't locked in softleaf_to_folio() On arm64 server, we found folio that get from migration entry isn't locked in softleaf_to_folio(). This issue triggers when mTHP splitting and zap_nonpresent_ptes() races, and the root cause is lack of memory barrier in softleaf_to_folio(). The race is as follows: CPU0 CPU1 deferred_split_scan() zap_nonpresent_ptes() lock folio split_folio() unmap_folio() change ptes to migration entries __split_folio_to_order() softleaf_to_folio() set flags(including PG_locked) for tail pages folio = pfn_folio(softleaf_to_pfn(entry)) smp_wmb() VM_WARN_ON_ONCE(!folio_test_locked(folio)) prep_compound_page() for tail pages In __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages are visible before the tail page becomes non-compound. smp_wmb() should be paired with smp_rmb() in softleaf_to_folio(), which is missed. As a result, if zap_nonpresent_ptes() accesses migration entry that stores tail pfn, softleaf_to_folio() may see the updated compound_head of tail page before page->flags. This issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio() because of the race between folio split and zap_nonpresent_ptes() leading to a folio incorrectly undergoing modification without a folio lock being held. This is a BUG_ON() before commit 93976a20345b ("mm: eliminate further swapops predicates"), which in merged in v6.19-rc1. To fix it, add missing smp_rmb() if the softleaf entry is migration entry in softleaf_to_folio() and softleaf_to_page(). [[email protected]: update function name and comments]
Timeline
ID reserved
By Linux
- 44 days later
· 44 days later
Published
- 7 months later
· 7 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
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium4.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.09% · top 99% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.7.
Affected products
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 426ee10711586617da869c8bb798214965337617
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 722cfaf6b31d31123439e67b5deac6b1261a3dea
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 7ddcf4a245c1c5a91fdd9698757e3d95179ffe41
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < b8c49ad888892ad7b77062b9c102b799a3e9b4f8
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 7ad1997b9bc8032603df8f091761114479285769
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7
- affected e9b61f19858a5d6c42ce2298cf138279375d0d9b – < 4c5e7f0fcd592801c9cc18f29f80fbee84eb8669
- affected 4.5
- unaffected < 4.5
- unaffected 5.10.253 – ≤ 5.10.*
- unaffected 5.15.203 – ≤ 5.15.*
- unaffected 6.1.168 – ≤ 6.1.*
- unaffected 6.6.134 – ≤ 6.6.*
- unaffected 6.12.81 – ≤ 6.12.*
- unaffected 6.18.21 – ≤ 6.18.*
- unaffected 6.19.11 – ≤ 6.19.*
- unaffected 7.0 – ≤ *
References
References11
- https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617 (opens in a new tab)
- https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd (opens in a new tab)
- https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea (opens in a new tab)
- https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41 (opens in a new tab)
- https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8 (opens in a new tab)
- https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769 (opens in a new tab)
- https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7 (opens in a new tab)
- https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669 (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-24811 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-31466)Record last updated .