[CVE-2026-99248][LOW] i2c: xiic: restore non-managed runtime PM to fix clk WARN flood

[CVE-2026-99248][LOW] i2c: xiic: restore non-managed runtime PM to fix clk WARN flood

[AL-KERNEL]

CVE: CVE-2026-99248
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: i2c: xiic: restore non-managed runtime PM to fix clk WARN flood
Commit: 47e105bdc863f2b320f9c05c80a63d3b83312700
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47e105bdc863f2b320f9c05c80a63d3b83312700
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99248
Analysis date: Tue, 03 Nov 2026 22:19:19 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
XIIC runtime-PM teardown can double-disable its clock and emit repeated WARNs, becoming a host panic only when WARNs are configured as fatal.

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

The original Linux kernel CVE announcement for CVE-2026-99248 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99248

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: LOW
Manual review required: NO

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

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

CVE-2026-99248	LOW	https://www.kernelcve.org/list/?q=CVE-2026-99248 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-404;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'The XIIC driver can disable its clock twice during device removal because managed runtime PM teardown clears autosuspend before disabling runtime PM and releases the managed clock later. An armed autosuspend timer can run xiic_i2c_runtime_suspend and disable the clock before devres calls clk_disable_unprepare again which produces repeated clk already disabled WARN messages. For the CVSS the PR:H base value reflects that removing or unbinding this platform device normally requires administrative control. For the CVSS the PR:L worst case covers a delegated device management environment. No UAF OOB access or other concrete memory corruption primitive is shown. Availability impact is normally limited but can become a kernel crash on systems configured with panic_on_warn. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. The independent weaker Aegis shadow evaluated CVSS 2.2 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	USB INIT RACE LEAK ERRORPATH UAF DMAorINTERRUPT HARDWARE LINUS 	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 0.
* Conservative score: 0; the patch proves a clock-enable accounting imbalance and WARN flood, not a fatal failure.
* Raw paranoid score: 1.
* Paranoid score: 1; +1 because the deterministic WARN can panic when `panic_on_warn` is enabled.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* Paranoid +1 — repeated `clk_core_disable()` WARN can become a kernel panic under the specifically supplied `panic_on_warn` configuration.
* No corruption points — no UAF, OOB access, stale object use, refcount mutation, or attacker-directed write is shown.
* No base crash point — WARN alone is nonfatal, and the ordinary effect is warning/log flooding.
* No extra availability point — any configured panic is the same WARN consequence.
* No authorization or protected-resource signal; B4-PENDING does not apply.
* No B5-R retry-accumulated OOB or B3 shared-backing write mechanics exist.

3. Reachability analysis

The vulnerable sequence occurs during probe failure or platform-device removal/devres teardown. Unbinding or removing this device normally uses administrative device-management control, but the supplied evidence does not prove that every deployment requires effective host-administrator powers; delegated management is only identified as a possible environment. Therefore `HostAdminRequired` and host UID requirements remain unknown rather than being assumed. No namespace-scoped complete trigger, remote path, ordinary-user path, special attacker-controlled retry sequence, or race requiring a security attacker is established.

4. Primitive and severity reading

The defect is an ordering imbalance: runtime autosuspend can disable the clock before the later managed clock release disables it again. The shown result is a clock-framework WARN, not memory corruption or a lifetime violation. A panic is configuration-dependent and provides no useful primitive beyond availability. Consequently this is `PrimitiveClass=NONE`, is not an Important candidate, and may be automatically downgraded.

5. One-sentence report phrase

XIIC runtime-PM teardown can double-disable its clock and emit repeated WARNs, becoming a host panic only when WARNs are configured as fatal.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch shows only a teardown-order WARN with no unresolved corruption, authorization, ownership, or trust-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: i2c: xiic: restore non-managed runtime PM to fix clk WARN flood
Commit: 47e105bdc863f2b320f9c05c80a63d3b83312700
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47e105bdc863f2b320f9c05c80a63d3b83312700

Commit description:

The devres conversion replaced manual pm_runtime_enable()/disable() with
devm_pm_runtime_set_active_enabled() and dropped the remove-time runtime
PM teardown. The managed release tears runtime PM down in the wrong
order: it calls pm_runtime_dont_use_autosuspend() before
pm_runtime_disable(), i.e. while runtime PM is still enabled, and devres
is LIFO so the devm_clk_get_enabled() release runs afterwards.

At remove(), pm_runtime_put_sync() leaves the device active with the
autosuspend timer armed. Clearing use_autosuspend then makes rpm_idle()
suspend immediately, and xiic_i2c_runtime_suspend() clk_disable()s the
clock. The later devm_clk_get_enabled() release clk_disable_unprepare()s
the already-disabled clock, so clk_core_disable() WARNs ("clkN already
disabled") on every teardown.

Drop the managed helper and restore the non-managed runtime PM setup and
teardown, so runtime PM is enabled once in probe and disabled once in
remove and the clock enable count stays balanced.

Order the remove teardown so runtime PM is disabled before the usage
count is dropped: pm_runtime_disable() followed by pm_runtime_put_noidle()
instead of pm_runtime_put_sync(). Dropping the count first with autosuspend
still enabled arms the autosuspend timer, and a preemption before
pm_runtime_disable() lets it expire, suspend the device and clk_disable()
the clock, which the devm release then disables again - the same WARN.

Restore the non-managed IRQ request as well. The probe error paths now
unwind runtime PM by hand via goto, and a devm-registered handler is only
freed later during devres unwind, so it would stay live across the manual
teardown (and across any future failing step added after it). Request the
IRQ with request_threaded_irq() and free it explicitly in the probe error
path and in remove. The probe error path also clears use_autosuspend, to
match the teardown in remove().

Fixes: 50c6349 ("i2c: xiic: switch to devres managed APIs")
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Cc: <stable@vger.kernel.org> # v7.1+
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://patch.msgid.link/20261014-i2c-xiic-restore-runtime-pm-teardown-v8-1-40668c270069@nexthop.ai
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/i2c/busses/i2c-xiic.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=47e105bdc863f2b320f9c05c80a63d3b83312700

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

The original Linux kernel CVE announcement for CVE-2026-99248 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99248

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:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 1

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).