[CVE-2026-99005][LOW] drm/i915/gt: Unmask interrupts only when ACTIVE is true

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

CVE: CVE-2026-99005
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/i915/gt: Unmask interrupts only when ACTIVE is true
Commit: 77abc1837c9651c8f43f7f7f336d10093eeb7745
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77abc1837c9651c8f43f7f7f336d10093eeb7745
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99005
Analysis date: Mon, 26 Oct 2026 23:43:06 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A narrow i915 RPS parking race can issue an MMIO interrupt-unmask operation without the runtime-PM wakelock, producing a warning and kernel taint without demonstrated memory corruption or host failure.

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

The original Linux kernel CVE announcement for CVE-2026-99005 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99005

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-2026-99005	LOW	https://www.kernelcve.org/list/?q=CVE-2026-99005 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE)	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-362;CWE-367;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race between intel_rps_boost and asynchronous GT parking can leave queued rps work running after ACTIVE was cleared and the runtime PM wakelock was dropped. The worker can then unmask RPS PM interrupts and perform an MMIO access while the GT is parked. The demonstrated result is an RPM wakelock assertion warning and kernel taint rather than UAF, OOB access, information disclosure, or arbitrary memory modification. For the CVSS the PR:L value is selected because triggering requires a local user or process producing GPU work and wait activity. AC:H reflects the narrow timing window involving asynchronous wakeref callbacks. Availability impact is low in the base case, while the paranoid case allows high availability impact if the invalid powered down MMIO access causes a GPU stall on affected hardware. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. 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. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	RACE HARDWARE TEST MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

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

1. ActionableScore

* Raw base score: -1.
* Conservative score: 0 after applying the score-range minimum.
* Raw paranoid score: -1.
* Paranoid score: 0 after applying the score-range minimum.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* -1 — Hard/narrow race: the stale ACTIVE observation must overlap two asynchronous wakeref callbacks during a small window before `queue_work()`.
* +0 — The demonstrated consequence is `assert_rpm_wakelock_held()` warning and kernel taint from an MMIO access while parked; no panic, host-wide DoS, or persistent GPU failure is shown.
* +0 — No UAF, OOB access, heap overwrite, stale allocation, authorization bypass, or active-state replacement/retirement violation is present.
* No crash/availability point: a possible GPU stall is only a paranoid theory in the legacy summary, while the commit says RPS resumes on the next unpark.
* No B5-R: there is no retry-accumulated index or heap OOB write.
* No B3-PENDING: no shared-backing write exists.
* No B4-PENDING: the ACTIVE check protects runtime-PM/MMIO sequencing, not an authorization decision.

3. Reachability analysis

A below-host-admin local process producing GPU work and waits can plausibly contribute to the sequence, so host UID 0 and host-administrator capability are not required. No namespace capability or privileged setup is identified. Triggering nevertheless depends on a narrow asynchronous parking/worker interleaving. Ordinary render-node access is plausible from the supplied evidence, but precise device-node permissions are not material because no security primitive is shown.

4. Primitive and severity reading

The exact defect is a check-to-use race allowing delayed RPS work to unmask interrupts and perform MMIO after GT parking and wakelock release. This is invalid device power-state access, classified CLASS_C. The shown effect is a warning and taint; a GPU hang, kernel panic, memory corruption, information disclosure, or protected-state modification is unproven. ImportantCandidate is therefore NO, and automatic downgrade is safe.

5. One-sentence report phrase

A narrow i915 RPS parking race can issue an MMIO interrupt-unmask operation without the runtime-PM wakelock, producing a warning and kernel taint without demonstrated memory corruption or host failure.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch and detailed call path establish only a constrained race-induced warning with no unresolved corruption or trust-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/i915/gt: Unmask interrupts only when ACTIVE is true
Commit: 77abc1837c9651c8f43f7f7f336d10093eeb7745
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77abc1837c9651c8f43f7f7f336d10093eeb7745

Commit description:

There is a small race window between intel_rps_boost() reading
a stale ACTIVE state and queuing rps->work, where ACTIVE may be
changed via asynchronous calls triggered by wakeref drop.
This means that rps_work() could be triggered after the GT has
been parked, so unmasking RPS PM interrupts would happen without
holding PM wakelock. This sequence of events may be observed
during live_rc6_ctx_wa() selftest:

1) live_rc6_ctx_wa()
   -> intel_engine_pm_put()
      -> wakeref_put()

ASYNC1) wakeref_put() callback
          -> __engine_park()
             -> intel_gt_pm_put_async()
                -> intel_gt_pm_put_async_untracked()
                   -> intel_wakeref_put_async()

ASYNC2) wakeref_put_async() callback
          -> __gt_park()
             -> intel_rps_park()
                -> intel_rps_clear_active() [clear ACTIVE]
                WITH INTERRUPTS:
                -> rps_disable_interrupts()
                   -> cancel_work_sync(rps->work)
                   -> rps_reset_interrupts() [rps->pm_iir = 0]
                WITHOUT INTERRUPTS (TIMER mode):
                -> rps_stop_timer()
                   -> cancel_work_sync(rps->work)

2) live_rc6_ctx_wa()
   -> intel_gt_wait_for_idle()
      -> intel_gt_retire_requests_timeout()
         -> dma_fence_wait_timeout()
            -> ops->wait() [i915_fence_wait()]
               -> i915_request_wait_timeout()
                  -> intel_rps_boost()
                     -> intel_rps_is_active() [check ACTIVE]
                        [OPEN RACE WINDOW]
                     -> queue_work(rps->work)
         -> retire_requests()
            -> i915_request_retire()
               -> intel_rps_dec_waiters() [from 1 to 0]

If ASYNC1 and ASYNC2 would execute during [OPEN RACE WINDOW],
then:

3) rps_work() executes from the workqueue and may satisfy
   "(!pm_iir && !client_boost)" test (in TIMER mode rps->pm_iir
   is zeroed by an earlier rps_work() call or never gets a new
   value after previous intel_rps_unpark() event), so it jumps
   to "out" label, bypassing intel_rps_is_active() guard and
   executes gen6_gt_pm_unmask_irq();

4) GT is parked and runtime PM wakelock is dropped, so only
   a raw reference in __gt_park() ->
   intel_display_power_put_async() remains for 100ms, then the
   MMIO write in gen6_gt_pm_unmask_irq() detects missing
   wakelock via assert_rpm_wakelock_held() and emits
   "RPM wakelock ref not held during HW access" tainting kernel.

Commit 3e7abf8 ("drm/i915: Extract GT render power state management")
dropped the "if (rps->interrupts_enabled)" guard that
gen6_pm_rps_work() had around this unmask in i915_irq.c.
INTEL_RPS_ACTIVE brackets the same window, since it is set in
intel_rps_unpark() before rps_enable_interrupts() and
rps_start_timer() and cleared in intel_rps_park() before
rps_stop_timer() and rps_disable_interrupts().

Skip unmasking when RPS is no longer active (reaching unmask
operation is independent of INTERRUPT mode). This does not
prevent RPS operation from resuming on the next unpark.
In interrupt mode, intel_rps_unpark() calls
rps_enable_interrupts(), which enables and unmasks the PM
interrupts. In timer mode, it calls rps_start_timer(),
restarting periodic engine-busyness evaluation. The timer
generates software RPS events and queues rps_work() directly,
independently of PM interrupt delivery. Neither mode requires
the late worker to unmask interrupts while the GT is parked


[Commit description truncated; see the upstream URL below]

Changed files:
  drivers/gpu/drm/i915/gt/intel_rps.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=77abc1837c9651c8f43f7f7f336d10093eeb7745

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

The original Linux kernel CVE announcement for CVE-2026-99005 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99005

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:L/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: unknown
  Paranoid ActionableScore: 0

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).