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Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2025-21939MEDIUM
Linux Linux — drm/xe/hmm: Don't dereference struct page pointers without notifier lock
  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  N  N  H    5.5   .0020   10.4     —
AFFECTED
  Product  Versions                                    Fixed
  Linux    81e058a3e7fd8593d076b4f26f7b8bb49f1d61e3 –  —
  Linux    6.10 –                                      6.12.19
TIMELINE
  Dec 29  Reserved by Linux
  Apr 1   Published (CNA: Linux)
  Jul 30  RESCORED — CVE-2025-21939 (Linux). CVSS 7.8 → 5.5 (NVD).
CWE-476 · CNA: Linux · CVSS v3.1 · 3 references · NVD status: Modified

Description

In the Linux kernel, the following vulnerability has been resolved: drm/xe/hmm: Don't dereference struct page pointers without notifier lock The pnfs that we obtain from hmm_range_fault() point to pages that we don't have a reference on, and the guarantee that they are still in the cpu page-tables is that the notifier lock must be held and the notifier seqno is still valid. So while building the sg table and marking the pages accesses / dirty we need to hold this lock with a validated seqno. However, the lock is reclaim tainted which makes sg_alloc_table_from_pages_segment() unusable, since it internally allocates memory. Instead build the sg-table manually. For the non-iommu case this might lead to fewer coalesces, but if that's a problem it can be fixed up later in the resource cursor code. For the iommu case, the whole sg-table may still be coalesced to a single contigous device va region. This avoids marking pages that we don't own dirty and accessed, and it also avoid dereferencing struct pages that we don't own. v2: - Use assert to check whether hmm pfns are valid (Matthew Auld) - Take into account that large pages may cross range boundaries (Matthew Auld) v3: - Don't unnecessarily check for a non-freed sg-table. (Matthew Auld) - Add a missing up_read() in an error path. (Matthew Auld) (cherry picked from commit ea3e66d280ce2576664a862693d1da8fd324c317)

Lifecycle

Complete event history — 3 events, chronological
DateEventDetail
December 29, 2024ReservedReserved by Linux
April 1, 2025PublishedPublished (CNA: Linux)
July 30, 2026RESCOREDRESCORED — CVE-2025-21939 (Linux). CVSS 7.8 → 5.5 (NVD).

Affected

Affected products and packages — 2 rows
VendorProduct / PackageEcosystemVersion introducedFixed
LinuxLinux81e058a3e7fd8593d076b4f26f7b8bb49f1d61e3
LinuxLinux6.106.12.19

Weaknesses

CWE-476

References (3)

Related

Authoritative record: CVE-2025-21939 at cve.org

Vendors: linux

Weaknesses: CWE-476

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2025-21939 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.