[CVE-2026-97440][LOW] net: qrtr: fix node refcount leak on ctrl packet alloc failure [ Upstream

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

CVE: CVE-2026-97440
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: qrtr: fix node refcount leak on ctrl packet alloc failure [ Upstream
Commit: 477353db343663d5502ca442c6de785d2f23f273
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=477353db343663d5502ca442c6de785d2f23f273
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97440
Analysis date: Thu, 24 Sep 2026 19:42:26 -0400
ActionableScore: 2
ActionableScore lower bound: 1
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-2026-97440 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97440

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-2026-97440	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97440 CHECK WITH IMPACT FROM ORIG NN 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-401;*CWE-772;**CWE-400;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 reference leak in qrtr_send_resume_tx occurs when qrtr_node_lookup obtains a node reference and qrtr_alloc_ctrl_packet later fails under memory pressure. The error path returns ENOMEM without releasing the node, so repeated failures can retain QRTR node objects and consume kernel resources. For the CVSS the PR:L rating is used because reliably causing allocation failures normally requires a local user context capable of generating sustained memory pressure. The issue is not directly Internet reachable. QRTR is generally an internal IPC transport used on Qualcomm systems between the application processor and remote subsystems such as a modem. Impact is primarily denial of service through resource exhaustion. No memory corruption, information disclosure, integrity impact, or privilege escalation primitive is demonstrated by the patch.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	SIMPLEFIX LEAK SKB IMPROVEONLY PACKET 	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

The paranoid score is emitted because sustained allocation failures could accumulate leaked node references and cause broader resource exhaustion. No floor or cap was applied.

2. Signal breakdown

* +1 Concrete persistent kernel resource/reference leak. `qrtr_node_lookup()` acquires a node reference and the `-ENOMEM` path returns without `qrtr_node_release(node)`. The reference leak is directly established by the patch.
* +1 Paranoid only. Repeated execution of the allocation-failure path can accumulate retained QRTR node references and may produce meaningful availability impact through resource exhaustion.

Non-awarded signals:

* No real UAF. The defect retains a reference instead of prematurely releasing one. No object is freed while a stale user remains.
* No repeated release/refcount mutation. The patch adds the missing first release and does not fix a second release through a dangling reference.
* No controlled reclaim, arbitrary write, OOB access, callback control, or active-object corruption is established.
* No confidentiality or integrity signal. A leaked reference does not itself disclose or modify protected data.
* No reliable kernel crash signal. The demonstrated behavior is a resource leak after an allocation failure.
* No remote reachability signal. The supplied patch does not establish that an untrusted remote party can trigger the complete path.
* No local unprivileged trigger signal. A local attacker may be able to contribute memory pressure, but the supplied evidence does not establish that the same below-host-admin actor can reliably invoke the QRTR `RESUME_TX` path repeatedly.
* No privilege penalty. Host-admin-equivalent access is not proven, but below-host-admin access for the complete trigger is also not proven.

3. Reachability analysis

`qrtr_send_resume_tx()` handles QRTR control traffic and calls `qrtr_node_lookup()` before allocating a control packet. The leak occurs only if `qrtr_alloc_ctrl_packet(..., GFP_KERNEL)` fails.

The supplied evidence does not establish who can repeatedly invoke this exact path. QRTR is commonly used as an internal Qualcomm IPC transport between the application processor and remote subsystems such as a modem. This is not equivalent to direct Internet reachability.

A practical trigger requires both repeated execution of the relevant QRTR control path and repeated allocation failures. Local memory pressure alone is insufficient unless the attacker can also reach the affected QRTR operation. The relevant capability and namespace checks are not visible, so host-admin and namespace-scoped reachability remain unknown.

No special hardware prerequisite is proven by the patch, but QRTR deployment itself is platform dependent. This is not scored as a niche-subsystem penalty because the attacker reachability restriction is not concretely established.

4. Primitive and severity interpretation

The exact primitive is a missing reference release on an allocation-failure path:

`qrtr_node_lookup()` obtains a node reference
`qrtr_alloc_ctrl_packet()` fails
the function returns `-ENOMEM`
the node reference remains retained

This is a concrete persistent resource/reference leak, not a lifetime violation. The retained object remains referenced rather than becoming stale, freed, or reused. Therefore this is neither an active structured-object UAF nor fixed stale storage.

The demonstrated consequence is gradual kernel resource retention under repeated failures. A broader denial of service through accumulated resource exhaustion is technically plausible but depends on sustained allocation failures and repeated reachability of the path. No memory-corruption, disclosure, integrity, security-boundary bypass, privilege-escalation, or controlled-reuse mechanism is established.

PrimitiveClass is `NONE` because the patch establishes a resource-management bug without a meaningful corruption, authorization, or lifetime primitive. ImportantCandidate is `NO` because the issue does not retain unresolved Important-grade exploitation leverage. AutoDowngradeAllowed is `YES` because the patch supports a constrained resource leak without evidence of corruption or boundary impact.

Likely operational severity is Low to ordinary Moderate, depending on whether the affected QRTR control path is repeatedly reachable in the deployed environment.

5. One-sentence report phrase

A missing `qrtr_node_release()` call after control packet allocation failure leaks QRTR node references and may cause resource exhaustion after sustained repeated failures, but no memory-corruption or privilege-escalation primitive is established.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a bounded reference leak on an allocation-failure path. There is no UAF, double release, stale-object use, authorization bypass, direct remote exposure, or demonstrated host-wide failure.

7. Call-site confidence

Call-site confidence: medium

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

Patch: net: qrtr: fix node refcount leak on ctrl packet alloc failure [ Upstream
Commit: 477353db343663d5502ca442c6de785d2f23f273
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=477353db343663d5502ca442c6de785d2f23f273

Changed files:
  net/qrtr/af_qrtr.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=477353db343663d5502ca442c6de785d2f23f273

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

The original Linux kernel CVE announcement for CVE-2026-97440 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97440

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: 1
  Paranoid ActionableScore: 2

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).