[CVE-2026-64377][MODERATE 7.0] cpufreq: qcom-cpufreq-hw: Fix possible double free

[CVE-2026-64377][MODERATE 7.0] cpufreq: qcom-cpufreq-hw: Fix possible double free

[AL-KERNEL]

CVE: CVE-2026-64377
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: cpufreq: qcom-cpufreq-hw: Fix possible double free
Commit: 28a03a3f6e6cda0b0da3b43761d175dec5d14d13
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=28a03a3f6e6cda0b0da3b43761d175dec5d14d13
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64377
Analysis date: Sat, 25 Jul 2026 07:34:02 -0400
ActionableScore: 7
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A double free or invalid free in qcom-cpufreq-hw can occur because devm managed per-domain cpufreq data is manually freed during policy exit, potentially causing a kernel crash and requiring manual review for kernel heap corruption impact.

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

The original Linux kernel CVE announcement for CVE-2026-64377 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64377

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-2026-64377	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-415;CWE-763;CWE-762;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.8';DESCR 'qcom_cpufreq.data is allocated with devm_kzalloc during probe as an array of per domain objects, but qcom_cpufreq_hw_cpu_exit called kfree on policy driver_data which points to one element of that devm managed array. For the first domain this can free the devm allocation while the devres entry remains active and later cause a double free on device detach. For other domains the pointer may refer inside the array and kfree can become an invalid free. For the CVSS the PR:L is used for the paranoid score because reliable triggering normally needs local control over CPU hotplug, driver teardown, or power management paths, but such control may be delegated to a reduced capability admin, service account, or container management context in some deployments. The issue is not network reachable. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to kernel heap memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	YES	DANGER HARDWARE LINUS KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7	YES	NO	checked

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

ActionableScore=7
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Paranoid score signals:

* Memory corruption, Strong corruption primitive: +2. The bug is a possible double free or invalid free in kernel memory management.
* Real lifetime corruption: +1. devm managed memory is manually freed while devres still owns the allocation.
* Reliable kernel crash / strong DoS: +1. Double free or invalid free during CPU policy teardown or device detach can plausibly crash the kernel.
* Privileged kernel/device-management memory corruption path: +1. The issue is in cpufreq driver teardown and platform-device lifetime handling.
* Weak LPE concern: +1. Kernel heap double free can theoretically support privilege escalation, but no reclaim or controlled overwrite primitive is shown.
* Confidentiality impact plausible: +1. Counted only for the paranoid interpretation due to kernel heap corruption potential.
* Integrity impact plausible: +1. Counted only for the paranoid interpretation due to kernel heap corruption potential.
* Requires elevated local control in typical deployments: -1. Triggering usually needs CPU hotplug, driver teardown, or device detach control, but this may be delegated to service or reduced-capability admin contexts rather than full host-root.

Conservative score signals:

* Memory corruption, Strong corruption primitive: +2.
* Real lifetime corruption: +1.
* Reliable kernel crash / strong DoS: +1.
* Privileged kernel/device-management memory corruption path: +1.
* Requires admin/root/CAP_* in typical deployments: -2.

## 3. Reachability analysis

This is not network reachable. The affected path is local and device-management related, likely requiring control over cpufreq policy teardown, CPU hotplug, driver unload, platform-device detach, or related power-management lifecycle events on Qualcomm platforms using qcom-cpufreq-hw.

In typical deployments this is not reachable by an ordinary unprivileged user. However, container orchestration, Android/vendor power-management services, test frameworks, or reduced-capability service accounts may have partial control over CPU or device lifecycle operations, so the paranoid score uses a reduced privilege penalty rather than treating the attacker as full host root.

Call-site confidence: medium. The patch shows the exact bad free site and the commit explains the allocation and ownership model, but no full caller sequence or crash trace is provided.

## 4. Severity interpretation

This is more than an ordinary Moderate correctness fix because it is a real kernel lifetime bug involving an invalid free or double free. Realistically, the most likely impact is local kernel crash during teardown or detach on affected Qualcomm systems. Theoretical privilege escalation is plausible because double free is a kernel heap corruption class, but the patch does not show attacker-controlled reclaim, controlled replacement, arbitrary write, or a demonstrated LPE path.

Therefore the conservative result is borderline/manual-review, while the paranoid result is a Strong Important candidate or at least Actionable Moderate.

## 5. One-sentence report phrase

A double free or invalid free in qcom-cpufreq-hw can occur because devm managed per-domain cpufreq data is manually freed during policy exit, potentially causing a kernel crash and requiring manual review for kernel heap corruption impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a kernel double-free / invalid-free lifetime bug in a privileged device-management path. Even if practical exploitation is likely limited and hardware-specific, the memory corruption class is strong enough to avoid auto-close.

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

Patch: cpufreq: qcom-cpufreq-hw: Fix possible double free
Commit: 28a03a3f6e6cda0b0da3b43761d175dec5d14d13
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=28a03a3f6e6cda0b0da3b43761d175dec5d14d13

Commit description:

qcom_cpufreq.data is allocated with devm_kzalloc() in probe() as an
array of per-domain data. qcom_cpufreq_hw_cpu_init() stores a pointer to
one element of this array in policy->driver_data.

qcom_cpufreq_hw_cpu_exit() currently calls kfree() on policy->driver_data.
This is not valid because the memory is devm-managed. For the first
domain, this can free the devm-managed allocation while the devres entry
is still active, leading to a possible double free when the platform
device is later detached. For other domains, the pointer may refer to an
element inside the array rather than the allocation base.

Remove the kfree(data) call and let devres release qcom_cpufreq.data.

This issue was found by a static analysis tool I am developing.

Fixes: 054a3ef ("cpufreq: qcom-hw: Allocate qcom_cpufreq_data during probe")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/cpufreq/qcom-cpufreq-hw.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=28a03a3f6e6cda0b0da3b43761d175dec5d14d13

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

The original Linux kernel CVE announcement for CVE-2026-64377 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64377

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:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 7

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: YES
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).