mm/migrate: fix shmem xarray update during migration
Published Apr 8, 2025
7.8
HIGHCVSS 3.1
EPSS 0.21%
Description
A shmem folio can be either in page cache or in swap cache, but not at the same time. Namely, once it is in swap cache, folio->mapping should be NULL, and the folio is no longer in a shmem mapping.
In __folio_migrate_mapping(), to determine the number of xarray entries to update, folio_test_swapbacked() is used, but that conflates shmem in page cache case and shmem in swap cache case. It leads to xarray multi-index entry corruption, since it turns a sibling entry to a normal entry during xas_store() (see [1] for a userspace reproduction). Fix it by only using folio_test_swapcache() to determine whether xarray is storing swap cache entries or not to choose the right number of xarray entries to update.
[1] https://lore.kernel.org/linux-mm/Z8idPCkaJW1IChjT@casper.infradead.org/
Note: In __split_huge_page(), folio_test_anon() && folio_test_swapcache() is used to get swap_cache address space, but that ignores the shmem folio in swap cache case. It could lead to NULL pointer dereferencing when a in-swap-cache shmem folio is split at __xa_store(), since !folio_test_anon() is true and folio->mapping is NULL. But fortunately, its caller split_huge_page_to_list_to_order() bails out early with EBUSY when folio->mapping is NULL. So no need to take care of it here.
Affected products
-
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version
-
- Version 6.1.71StatusaffectedConstraints<6.1.132
- Version 6.6.10StatusaffectedConstraints<6.6.85
- Version
-
- Version 6.7StatusaffectedConstraints-
- Version 0StatusunaffectedConstraints<6.7
- Version 6.1.132StatusunaffectedConstraints<=6.1.*
- Version 6.12.21StatusunaffectedConstraints<=6.12.*
- Version 6.13.9StatusunaffectedConstraints<=6.13.*
- Version 6.14StatusunaffectedConstraints<=*
- Version 6.6.85StatusunaffectedConstraints<=6.6.*
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
| ||||||||||||||||||||||||
| Linux | Linux | unaffected |
| ||||||||||||||||||||||||
| Linux | Linux | affected |
|
- ≥ 6.1.71 · < 6.1.132
- ≥ 6.6.10 · < 6.6.85
- ≥ 6.7.1 · < 6.12.21
- ≥ 6.13 · < 6.13.9
- 6.7
- 6.7
- 6.14
- 6.14
- 6.14
- 6.14
- 6.14
- 6.14
- 6.14
No data.
Red Hat Enterprise Linux 10
kernel
Fix deferred
Red Hat Enterprise Linux 6
kernel
Out of support scope
Red Hat Enterprise Linux 7
kernel
Out of support scope
Red Hat Enterprise Linux 7
kernel-rt
Out of support scope
Red Hat Enterprise Linux 8
kernel
Not affected
Red Hat Enterprise Linux 8
kernel-rt
Not affected
Red Hat Enterprise Linux 9
kernel
Fix deferred
Red Hat Enterprise Linux 9
kernel-rt
Fix deferred
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | n/a |
| Red Hat Enterprise Linux 7 | kernel | Out of support scope | n/a |
| Red Hat Enterprise Linux 7 | kernel-rt | Out of support scope | n/a |
| Red Hat Enterprise Linux 8 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | n/a |
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
1 other source (CVE.org) ▾
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 3, 2026.
Score over time
2025–2026- EPSS v4
- EPSS v5
Percentile over time
- EPSS v4
- EPSS v5
Table of values (3 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 3, 2026 | 0.21% (0.00214) | 10.61th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.16% (0.00162) | 5.71th | v5 (v2026.06.15) |
| Apr 8, 2025 | 0.02% (0.00018) | 2.47th | v4 (v2025.03.14) |
References (12)
- https://access.redhat.com/security/cve/CVE-2025-22015 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2358228 Issue Tracking
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://git.kernel.org/stable/c/29124ae980e2860f0eec7355949d3d3292ee81da Patch
- https://git.kernel.org/stable/c/49100c0b070e900f87c8fac3be9b9ef8a30fa673 Patch
- https://git.kernel.org/stable/c/60cf233b585cdf1f3c5e52d1225606b86acd08b0 Patch
- https://git.kernel.org/stable/c/75cfb92eb63298d717b6b0118f91ba12c4fcfeb5 Patch
- https://git.kernel.org/stable/c/c057ee03f751d6cecf7ee64f52f6545d94082aaa Patch
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
- https://lore.kernel.org/linux-cve-announce/2025040843-CVE-2025-22015-3408@gregkh/T
- https://nvd.nist.gov/vuln/detail/CVE-2025-22015
- https://www.cve.org/CVERecord?id=CVE-2025-22015
Change history (0)
No recorded changes yet.