[CVE-2026-64222][MODERATE 7.0] octeontx2-pf: avoid double free of pool->stack on AQ init failure [ Upstream

[CVE-2026-64222][MODERATE 7.0] octeontx2-pf: avoid double free of pool->stack on AQ init failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64222
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: octeontx2-pf: avoid double free of pool->stack on AQ init failure [ Upstream
Commit: e6e9bc0bf963662b7042048ab0281014625d4cb4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e6e9bc0bf963662b7042048ab0281014625d4cb4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64222
Analysis date: Fri, 24 Jul 2026 12:24:14 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A double free in the OcteonTX2/CN20K NIC AQ initialization error path can leave pool stack stale after qmem_free and later free it again during shared cleanup, causing local kernel memory corruption and likely DoS on affected hardware.

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

The original Linux kernel CVE announcement for CVE-2026-64222 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64222

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 7.0
Manual review required: YES

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

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-64222	MODERATE	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:H/I:H/A:H';CWE-415;*CWE-416;*CWE-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A double free can occur in the OcteonTX2/CN20K NIC driver when AQ pool initialization fails after pool stack has already been freed locally. The stale pool stack pointer can later be passed to the shared cleanup path and freed again during partial initialization unwind. This is a local driver management path and is not directly network reachable. For the CVSS the PR:L in the paranoid score is used only for environments where a non-admin local service account, container root, or delegated net admin context can trigger device reset or driver reinitialization. In normal deployments PR:H is more realistic because the path is tied to privileged NIC and driver management. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact because double free is a memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	REMOTE INIT ERRORPATH NETWORK HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Generic memory corruption: +2. The patch fixes a confirmed double free of pool->stack.
* Real lifetime corruption: +1. The pointer remains stale after qmem_free and is later consumed by a shared cleanup path.
* Reliable kernel crash / strong DoS: +1. A double free in kernel driver cleanup can realistically crash the kernel or corrupt allocator state.
* Privileged kernel/device-management memory corruption path: +1. The bug is in NIC queue/pool initialization and cleanup, close to firmware mailbox and device-management logic.
* Requires admin/root/CAP_* in typical deployments: -2. Triggering driver load, reset, queue initialization, or recovery normally requires host administrative control.
* Rare hardware/device-specific condition: -1. The affected path requires OcteonTX2/CN20K hardware and a specific AQ initialization failure path.

Paranoid additional interpretation:

* Firmware-mediated external influence: +1. One failure path depends on otx2_sync_mbox_msg and device/firmware mailbox behavior.
* Weak LPE concern: +1. Double free is a real memory corruption primitive, but no controlled reclaim, overwrite target, callback control, or exploit chain is shown.
* Confidentiality impact plausible: +1. In the worst defensible case, allocator corruption from double free could affect kernel object lifetime.
* Integrity impact plausible: +1. Same reason, but this remains speculative without a demonstrated reuse primitive.
* Reduced privilege / delegated device-control interpretation: -1. In some deployments a service account, container root, or delegated net admin context may trigger reset or reinitialization without full host-root equivalence.

## 3. Reachability analysis

The bug is local and not directly network reachable through packet processing. A realistic trigger requires the OcteonTX2/CN20K NIC driver, affected hardware, and an AQ initialization failure such as mailbox sync failure or allocation failure. In normal deployments, the required operations are tied to privileged driver/device management, so PR:H is more realistic for CVSS-style reasoning. A paranoid interpretation can use PR:L only if a reduced-privilege service, container root with delegated device access, or local operator can provoke driver reset or reinitialization. Runtime reproduction is hardware-dependent, and the commit explicitly notes that validation was not performed because the path requires OcteonTX2/CN20K hardware.

Call-site confidence: medium-high. The commit explicitly identifies the later cleanup path through otx2_sq_aura_pool_init and otx2_aura_pool_free, but the full caller code is not included in the pasted diff.

## 4. Severity interpretation

This is more than an ordinary Moderate correctness issue because it is a confirmed double free, not just a leak or validation-only fix. Realistic exploitation is likely limited to local privileged DoS on specific hardware, because there is no evidence of attacker-controlled reclaim, object replacement, arbitrary write, or network trigger. The paranoid score treats it as Actionable Moderate because double free is a kernel memory-corruption primitive and should not be auto-closed without manual review, even though practical LPE evidence is weak.

## 5. One-sentence report phrase

A double free in the OcteonTX2/CN20K NIC AQ initialization error path can leave pool stack stale after qmem_free and later free it again during shared cleanup, causing local kernel memory corruption and likely DoS on affected hardware.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: confirmed double free and stale pointer lifetime bug in kernel driver cleanup. Practical exploitability is hardware-specific and likely privileged, but memory corruption makes auto-close inappropriate.

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

Patch: octeontx2-pf: avoid double free of pool->stack on AQ init failure [ Upstream
Commit: e6e9bc0bf963662b7042048ab0281014625d4cb4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e6e9bc0bf963662b7042048ab0281014625d4cb4

Changed files:
  drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.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=e6e9bc0bf963662b7042048ab0281014625d4cb4

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

The original Linux kernel CVE announcement for CVE-2026-64222 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64222

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 3
  Paranoid ActionableScore: 5

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 7.0

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).