CVE-2026-31466

Advisory lineage Upstream: 0 Downstream: 14
Analyzed
Published: 22 Apr 2026, 13:53
Last modified:14 Jul 2026, 12:47

Vulnerability Summary

Overall Risk (default)
low
19/100
CVSS Score
4.7 MEDIUM
v3.1 (nvd)
EPSS Score
0.09% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

22 Apr 2026, 13:53
Published
Vulnerability first disclosed
14 Jul 2026, 12:47
Last Modified
Vulnerability information updated

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(). [tujinjiang@huawei.com: update function name and comments]

CVSS Metrics

  • v3.1•MEDIUM•Score: 4.7CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.09%• Percentile: 1%

Techniques & Countermeasures

  • CWE-362•Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

    The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Affected Systems

  • linux•linux

    ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 426ee10711586617da869c8bb798214965337617 | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 722cfaf6b31d31123439e67b5deac6b1261a3dea | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 7ddcf4a245c1c5a91fdd9698757e3d95179ffe41 | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < b8c49ad888892ad7b77062b9c102b799a3e9b4f8 | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 7ad1997b9bc8032603df8f091761114479285769 | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7 | ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b, < 4c5e7f0fcd592801c9cc18f29f80fbee84eb8669 | 4.5

  • linux•linux kernel

    ≥ 4.5, < 5.10.253 | ≥ 5.11, < 5.15.203 | ≥ 5.16, < 6.1.168 | ≥ 6.2, < 6.6.134 | ≥ 6.7, < 6.12.81 | ≥ 6.13, < 6.18.21 | ≥ 6.19, < 6.19.11 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5

References (10)