[CVE-2026-98249][MODERATE 7.0] arm64: hibernate: pass HVC_SET_VECTORS args to the resume hvc

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-98249
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: arm64: hibernate: pass HVC_SET_VECTORS args to the resume hvc
Commit: 6646418d1032cac25110526161f60d255ed08397
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6646418d1032cac25110526161f60d255ed08397
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98249
Analysis date: Sun, 11 Oct 2026 02:56:07 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98249 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98249

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE 7.0
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98249	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98249 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE_KPANIC RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;*CWE-672;CWE-670;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'During arm64 hibernation resume, swsusp_arch_suspend_exit invokes HVC without setting x0 to HVC_SET_VECTORS or x1 to the restored vector address. VBAR_EL2 can therefore remain pointed at the temporary trans_pgd vector page after swsusp_free releases that page. A later EL2 exception may use freed, poisoned, or reused memory as its exception vector and the demonstrated result is a system hang after resume. The stale executable vector pointer also creates a potential use after free control flow condition if the released page is reused before an EL2 exception occurs. For the CVSS the PR:L value in the paranoid score reflects systems where a local account can request hibernation through delegated logind, polkit, or power management permissions without full administrator access. The issue is not network reachable. Impact is at least a local denial of service and in the worst still defensible case may include confidentiality and integrity impact through unintended EL2 control flow. The hardware, hibernation, page reuse, and exception timing requirements make exploitation complex.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	SIMPLEFIX HARDWARE LINUS  KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 5
* Raw paranoid score: 3
* Paranoid score: 5
* Applied conservative floor: 3 -> 5 because a real post-lifetime reference remains active as the EL2 exception-vector target, and later CPU execution can consume the freed page rather than merely faulting in cleanup.
* Applied paranoid floor: 3 -> 5 for the same established mechanism. No speculative reclaim or LPE bonus was added.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 Real UAF or lifetime violation. VBAR_EL2 remains directed at the temporary trans_pgd vector page after swsusp_free releases it.
* +1 Reliable strong DoS. A subsequent EL2 exception can consume the freed or poisoned page as exception-vector code, and a resume hang was reproduced with page poisoning.
* +0 Controlled reclaim. No attacker-controlled replacement of the freed page is demonstrated.
* +0 Strong or weak LPE leverage. Post-free instruction consumption at EL2 is security-relevant, but attacker control over the replacement contents is not established.
* +0 Additional availability. The demonstrated hang is the same consequence already counted as strong DoS.
* +0 Confidentiality and integrity. No disclosure, directed write, controlled instruction stream, or privilege escalation is demonstrated.
* +0 Remote reachability. Hibernation resume is a local host operation.
* +0 Race penalty. The defect is an ordered stale-vector sequence, not an established narrow race.
* +0 Hardware or configuration penalty. ARM64, EL2, and hibernation are prerequisites, but the evidence does not establish rare physical hardware. Page poisoning improves reproduction but is not required for the stale pointer to exist.
* No concrete repeated release or refcount operation exists. There is one page release followed by stale instruction consumption, not a second put or free.
* B5-R is not applicable because there is no retry-accumulated OOB write.
* B3-PENDING is not applicable because no shared-backing write is present.
* B4-PENDING is not applicable because no authorization decision changes from DENY to ALLOW.

3. Reachability analysis

The complete trigger requires an ARM64 system using the affected hibernation and EL2 vector-restoration path. Direct control through the kernel power interfaces normally involves host power-management authority, while some systems delegate hibernation requests through logind or polkit. The supplied evidence does not establish which policy applies to the evaluated deployment, so HostAdminRequired remains UNKNOWN rather than YES or NO.

The operation is host-global and is not available through an attacker-created user or network namespace, so NamespaceScopedPrivilege is NO. Prior support for hibernation and a usable resume configuration is required. CONFIG_PAGE_POISONING and page_poison improve detection and made the hang reproducible, but they are not the root requirement.

There is no network trigger. There is also no timing race in the fix. The stale state is created deterministically when the HVC dispatch falls through without updating VBAR_EL2. Exploitation beyond a hang would additionally require useful page reuse and a later EL2 exception, neither of which is shown to be attacker-controlled.

4. Primitive and severity interpretation

The exact primitive is a stale post-lifetime executable mapping reference. The temporary trans_pgd page contains an EL2 exception-vector copy, VBAR_EL2 remains pointed at it, and swsusp_free subsequently releases the page. A later EL2 exception can fetch instructions from memory outside the original page lifetime.

This is fixed stale storage, but it is stronger than an ordinary stale data-buffer dereference because the CPU may consume the page as privileged exception-vector code. It remains CLASS_B rather than CLASS_A because controlled reclaim, attacker-shaped replacement contents, directed control flow, arbitrary kernel access, and privilege escalation are not established.

The demonstrated consequence is a host hang during or after hibernation resume. The technically plausible but unproven consequence is unintended EL2 execution if the page is reused before an exception. ImportantCandidate is YES because the post-free use is an active privileged instruction-consumption path whose exploitation leverage cannot safely be dismissed from this two-line patch. AutoDowngradeAllowed is NO because automatic closure would discard that unresolved control-flow-relevant lifetime primitive.

5. One-sentence report phrase

During ARM64 hibernation resume, missing HVC_SET_VECTORS arguments can leave VBAR_EL2 pointing to a page freed by swsusp_free, allowing a later EL2 exception to consume post-lifetime memory as privileged vector code and causing at least a host hang.

6. Manual review recommendation

MANUAL CHECK REQUIRED

The demonstrated hang is moderate in isolation, but the stale reference is an active EL2 instruction target rather than a shallow cleanup pointer, so page-reuse behavior and post-resume exception timing require human review.

7. Call-site confidence

Call-site confidence: high

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: arm64: hibernate: pass HVC_SET_VECTORS args to the resume hvc
Commit: 6646418d1032cac25110526161f60d255ed08397
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6646418d1032cac25110526161f60d255ed08397

Commit description:

swsusp_arch_suspend_exit() reinstalls the restored kernel's hyp stub
vectors with an hvc, but never passes the arguments. x0 is not set to
HVC_SET_VECTORS and x1 is not set to the vector address, so the stub
dispatch falls through and returns without writing vbar_el2. EL2 is
left pointing at the trans_pgd copy of the vectors, a page that
swsusp_free() releases right after resume.

Set the arguments up the same way __hyp_set_vectors() does.

Without this fix, Vladimir was able to trigger a hang when resuming from
hibernation with CONFIG_PAGE_POISONING=y and page_poison=on.

Fixes: 788bfdd ("arm64: trans_pgd: hibernate: Add trans_pgd_copy_el2_vectors")
Cc: stable@vger.kernel.org
Signed-off-by: Bradley Morgan <include@grrlz.net>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  arch/arm64/kernel/hibernate-asm.S

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6646418d1032cac25110526161f60d255ed08397

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98249 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98249

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 5

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): MODERATE 7.0

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).