Bug 2393192 (CVE-2025-38686) - CVE-2025-38686 kernel: userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry
Summary: CVE-2025-38686 kernel: userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a ...
Keywords:
Status: NEW
Alias: CVE-2025-38686
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
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Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-09-04 16:04 UTC by OSIDB Bzimport
Modified: 2025-09-04 17:40 UTC (History)
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Description OSIDB Bzimport 2025-09-04 16:04:15 UTC 
In the Linux kernel, the following vulnerability has been resolved:

userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry

When UFFDIO_MOVE encounters a migration PMD entry, it proceeds with
obtaining a folio and accessing it even though the entry is swp_entry_t. 
Add the missing check and let split_huge_pmd() handle migration entries. 
While at it also remove unnecessary folio check.

[surenb: remove extra folio check, per David]
Comment 1 Jon Moroney 2025-09-04 17:37:41 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025090447-CVE-2025-38686-281b@gregkh/T
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