xenbus: Use kref to track req lifetime

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-37949
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-05-20 16:15:32 UTC
Updated2026-07-30 06:22:36 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: <TASK> __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case. It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data. Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed. Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it. This use of kref matches the description in Documentation/core-api/kref.rst

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-476

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 0e94a246bb6d9538010b6c02d2b1d4717a97b2e5 git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d f1bcac367bc95631afbb918348f30dec887d0e1b git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 4d260a5558df4650eb87bc41b2c9ac2d6b2ba447 git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 8b02f85e84dc6f7c150cef40ddb69af5a25659e5 git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d cbfaf46b88a4c01b64c4186cdccd766c19ae644c git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 8e9c8a0393b5f85f1820c565ab8105660f4e8f92 git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 2466b0f66795c3c426cacc8998499f38031dbb59 git Not specified
CNA Linux Linux affected fd8aa9095a95c02dcc35540a263267c29b8fda9d 1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27 git Not specified
CNA Linux Linux affected 4.11 Not specified
CNA Linux Linux unaffected 4.11 semver Not specified
CNA Linux Linux unaffected 5.4.294 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.238 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.183 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.139 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.91 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.29 6.12.* semver Not specified
CNA Linux Linux unaffected 6.14.7 6.14.* semver Not specified
CNA Linux Linux unaffected 6.15 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/08/msg00010.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Third Party Advisory
git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/10/msg00007.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Third Party Advisory
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