* [CVE-2026-98319][LOW] drm: Fix drm_pending_vblank_event leak in error path for out_fence_ptr [ Upstream
@ 2026-10-10 3:56 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 3:56 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98319
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm: Fix drm_pending_vblank_event leak in error path for out_fence_ptr [ Upstream
Commit: 3d6576ed3de01e8a378397b7020e33ae3d40aa6c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d6576ed3de01e8a378397b7020e33ae3d40aa6c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98319
Analysis date: Fri, 09 Oct 2026 23:56:15 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98319 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98319
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-2026-98319 LOW https://www.kernelcve.org/list/?q=CVE-2026-98319 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both LOW) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A resource leak in the DRM atomic signaling path can occur when out_fence_ptr is supplied without DRM_MODE_PAGE_FLIP_EVENT and a later allocation or setup_out_fence operation fails. The allocated drm_pending_vblank_event has no base fence and is not released by complete_signaling, so repeated failures may retain kernel memory and DRM event resources. For the CVSS the PR:L reflects that a local process must have access to the relevant DRM device and sufficient DRM master or lease permissions to submit the affected atomic operation. The issue is not network reachable. The demonstrated impact is limited resource retention and possible local denial of service after repeated triggering. There is no demonstrated UAF, OOB access, information disclosure, or write primitive. The base impact is A:L because immediate host wide exhaustion is not established. The paranoid A:H value applies only if sustained repetition across operations or DRM file contexts can accumulate enough retained resources to affect the system.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE INIT NOMEMCHK SIMPLEFIX LEAK ERRORPATH HARDWARE LINUS MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
PrimitiveClass=CLASS_C
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 conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap changed either score.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Concrete kernel resource leak. `drm_pending_vblank_event` is allocated but not released when `krealloc()`, `drm_crtc_create_fence()`, or `setup_out_fence()` fails. The normal completion path cannot release it because `base.fence` was never assigned.
* No negative privilege penalty. The complete DRM master or lease requirement is unresolved, so host-administrator privilege is not assumed.
* No additional resource-exhaustion point. Repeated leakage is plausible, but rapid or host-wide exhaustion, persistence beyond DRM file teardown, and bypass of per-file event accounting are not established.
* No crash point. The supplied evidence establishes retained resources, not a kernel panic or reliable host-wide DoS.
* No UAF, double release, OOB access, arbitrary write, controlled reclaim, disclosure, or authorization bypass is established.
* B5-R does not apply because there is no heap OOB write, retry-accumulated offset, or later consumption of corrupted state.
* B3-PENDING does not apply because no shared-backing write occurs.
* B4-PENDING does not apply because no DENY-to-ALLOW authorization decision is changed.
3. Reachability analysis
The vulnerable path is reached through a DRM atomic operation using `out_fence_ptr` without `DRM_MODE_PAGE_FLIP_EVENT`, followed by an allocation or `setup_out_fence()` failure. A process with suitable DRM/KMS control may be able to cause the latter failure repeatedly, but the supplied context does not establish that an ordinary logged-in user can complete the affected operation.
A compositor, DRM master, leased display client, or delegated display service may operate below host-administrator privilege, but exact access to the affected CRTC and atomic commit path is not shown. Therefore `HostAdminRequired` and namespace-scoped privilege remain unknown. Numeric host UID 0 is not established as required.
No network trigger, race, boot option, unusual hardware requirement, or attacker-created namespace path is established. A DRM/KMS-capable device and an appropriate display-control context are prerequisites, but common GPU hardware is not treated as rare.
4. Primitive and severity interpretation
The exact primitive is a missing cleanup operation that retains a `drm_pending_vblank_event` and may also retain an associated event reservation. The object is not freed and subsequently reused, so this is not a UAF or stale-object access. There is no second lifetime mutation, corrupted descriptor consumption, or security-boundary effect.
The patch redirects all relevant failures to `drm_event_cancel_free()` and clears `crtc_state->event`, preventing later completion code from observing the abandoned event. This supports `CLASS_C`: resource-retention behavior with possible availability degradation, but no independently useful corruption primitive.
The practical consequence is limited resource leakage. Sustained triggering could create memory or event pressure, but system-wide exhaustion is not demonstrated. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because no unresolved memory-corruption, ownership, authorization, or cross-boundary primitive remains.
5. One-sentence report phrase
A missing DRM atomic error-path cleanup can leak a pending vblank event and associated resources, but the supplied evidence does not establish memory corruption, authorization bypass, or reliable host-wide exhaustion.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The issue is a concrete but constrained resource leak without evidence of UAF, OOB access, strong DoS, or a security-boundary primitive.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm: Fix drm_pending_vblank_event leak in error path for out_fence_ptr [ Upstream
Commit: 3d6576ed3de01e8a378397b7020e33ae3d40aa6c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d6576ed3de01e8a378397b7020e33ae3d40aa6c
Changed files:
drivers/gpu/drm/drm_atomic_uapi.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=3d6576ed3de01e8a378397b7020e33ae3d40aa6c
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98319 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98319
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:L/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.5
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: 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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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