[CVE-2026-98415][MODERATE REGULAR] soc: samsung: exynos-pmu: fix use-after-free of interrupt generator node

[CVE-2026-98415][MODERATE REGULAR] soc: samsung: exynos-pmu: fix use-after-free of interrupt generator node

[AL-KERNEL]

CVE: CVE-2026-98415
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: soc: samsung: exynos-pmu: fix use-after-free of interrupt generator node
Commit: 4450102d6aa2a85b1d2d8610920fcbe45eb0ef69
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4450102d6aa2a85b1d2d8610920fcbe45eb0ef69
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98415
Analysis date: Wed, 14 Oct 2026 22:54:58 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
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-2026-98415 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98415

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 REGULAR
Manual review required: YES

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

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

CVE-2026-98415	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98415 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-416;*CWE-672;CWE-911;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A use-after-free can occur in the Samsung Exynos PMU setup path because the reference to intr_gen_node is released before the same device tree node pointer is passed to of_syscon_register_regmap(). If the node can be detached and freed after of_node_put(), the later access may dereference stale memory and cause a kernel fault or crash. The issue is local and platform specific. It is not directly network reachable and normally requires a Samsung Exynos system with the affected PMU configuration. For the CVSS the PR:H is selected because reliable attacker controlled triggering would normally require administrative control over dynamic device tree nodes or overlays. The confirmed impact is denial of service. In the paranoid interpretation the UAF may also permit confidentiality or integrity impact if freed node memory can be reclaimed in a controlled way, although no reliable arbitrary read or write primitive is established. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 4 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were KP and FD specialist checks stage MODERATE_KPANIC to MODERATE because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP. The independent weaker Aegis shadow evaluated CVSS 4.1 and ActionableScore 2 with primitive class CLASS_B and manual review RECOMMENDED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4)	MAYBE	INIT UAF HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 4
* Raw paranoid score: 3
* Paranoid score: 4
* Applied conservative floor: 3 -> 4 under REAL UAF FLOOR 4.
* Applied paranoid floor: 3 -> 4 under REAL UAF FLOOR 4.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +2 Real UAF and lifetime violation. `of_node_put(intr_gen_node)` can end the held reference lifetime, but the same pointer is subsequently passed to `of_syscon_register_regmap()`.
* +1 Realistic kernel crash or DoS. Dereferencing a freed `device_node` can produce a fault, although no observed panic is included.
* +0 Structured stale-object leverage. `device_node` is structured, but attacker-controlled reclaim, replacement contents, callback use, or a directed memory operation is not established.
* +0 Strong or weak LPE leverage. No useful post-free primitive beyond the stale object consumption is demonstrated.
* +0 Local unprivileged trigger. No ordinary-user interface capable of driving the complete lifetime sequence is identified.
* +0 Remote reachability. The setup path is not network-triggerable.
* +0 Authorization impact. No access-control decision or protected resource is involved.
* No privilege penalty was applied because host-admin control of the complete trigger is not positively established.
* No hardware penalty was applied merely because the code is specific to Samsung Exynos hardware.
* No race penalty was applied because the patch does not establish a narrow attacker-dependent race.

Repeated-release checks:

* The first `of_node_put()` can end the acquired reference lifetime.
* The same pointer survives and is used later.
* The later operation is not another `put`, release, free, or refcount mutation.
* Concrete repeated release/refcount +1 was not awarded.
* Paranoid repeated-refcount leverage +1 was not awarded.
* FLOOR 5 was not applied because there is no second lifetime mutation, controlled reclaim, or meaningful attacker-influenced stale state.

Not awarded:

* Controlled reclaim is not demonstrated.
* Arbitrary or directed read/write is not demonstrated.
* Confidentiality and integrity impact are not established.
* Extra Availability was not awarded because it would duplicate the same possible crash.
* NEW52 B5-R does not apply because there is no retry-accumulated OOB write.
* NEW53 B3-PENDING does not apply because there is no shared-backing write.
* NEW54 B4-PENDING does not apply because there is no authorization decision bypass.

3. Reachability analysis

The vulnerable function is part of Samsung Exynos PMU CPU hotplug and idle setup and requires a platform Device Tree containing `google,pmu-intr-gen-syscon`. The vulnerable sequence may occur during platform initialization without a userspace caller, but the supplied evidence does not establish how an attacker can force the node to be freed before its later use.

Dynamic Device Tree or overlay manipulation is a plausible way to affect node lifetime, but the complete operation, required capability checks, and timing are not shown. Therefore host-admin privilege cannot be positively marked either required or unnecessary. No namespace-scoped trigger is established.

The attacker cannot be assumed to instantiate the affected PMU device or Device Tree topology. Samsung Exynos hardware and the relevant firmware or boot-time Device Tree are prerequisites. The patch does not describe a repeatable userspace race, so no repeatability bonus or hard-race penalty is supported.

4. Primitive and severity interpretation

The exact primitive is a stale post-lifetime pointer use after prematurely dropping the reference obtained by `of_parse_phandle()`. The stale object is an active structured `device_node`, not a fixed DMA or transfer buffer. The pointer is later consumed by `of_syscon_register_regmap()`, but the visible evidence does not establish attacker influence over reclaimed contents or a useful structured-field operation after reuse.

This is CLASS_B because a real object-lifetime violation exists. It is not CLASS_A because controlled reclaim, directed corruption, callback influence, arbitrary read/write, authorization bypass, and privilege escalation are not established.

The demonstrated practical concern is a fault or kernel crash. More serious consequences from allocator reuse remain theoretical and are not scored. ImportantCandidate is NO because this is presently a constrained stale-object use without meaningful exploitation leverage. AutoDowngradeAllowed is YES because there is no repeated refcount mutation, security-boundary primitive, or unresolved controlled-corruption mechanism.

Likely operational severity is Borderline or ordinary Moderate on affected Exynos systems, with manual confirmation appropriate because the commit explicitly identifies a UAF.

5. One-sentence report phrase

A prematurely released Exynos interrupt generator device tree node is later passed to of_syscon_register_regmap(), creating a platform-specific use-after-free that can cause a kernel crash without a demonstrated controlled corruption or privilege-escalation primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether the affected platform permits the node to be detached or freed during this setup path and whether `of_syscon_register_regmap()` performs deeper stale-node processing than the supplied diff shows.

7. Call-site confidence

Call-site confidence: medium

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

Patch: soc: samsung: exynos-pmu: fix use-after-free of interrupt generator node
Commit: 4450102d6aa2a85b1d2d8610920fcbe45eb0ef69
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4450102d6aa2a85b1d2d8610920fcbe45eb0ef69

Commit description:

The setup_cpuhp_and_cpuidle() parses the device tree node for the
interrupt generation block via of_parse_phandle() and decrements its
reference count using of_node_put() immediately after fetching the resource
address. However, later the intr_gen_node pointer is passed into
of_syscon_register_regmap().

Fix this by declaring intr_gen_node with __free() and removing
of_node_put().

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260513-exynos850-cpuhotplug-v4-0-54fec5f65362@linaro.org?part=3
Fixes: 78b7289 ("soc: samsung: exynos-pmu: Enable CPU Idle for gs101")
Cc: stable@vger.kernel.org
Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
Link: https://patch.msgid.link/20260828-exynos-pmu-cpuhp-idle-fixes-v2-1-06bce6107bd6@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20260917081641.72291-2-krzk@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/soc/samsung/exynos-pmu.c

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=4450102d6aa2a85b1d2d8610920fcbe45eb0ef69

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

The original Linux kernel CVE announcement for CVE-2026-98415 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98415

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:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 4

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).