[CVE-2026-64080][MODERATE 7.0] firmware: arm_ffa: Snapshot notifier callbacks under lock [ Upstream

[CVE-2026-64080][MODERATE 7.0] firmware: arm_ffa: Snapshot notifier callbacks under lock [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64080
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: firmware: arm_ffa: Snapshot notifier callbacks under lock [ Upstream
Commit: d1e38551fadea230649bc428f0f35c9ee062a072
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1e38551fadea230649bc428f0f35c9ee062a072
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64080
Analysis date: Sun, 19 Jul 2026 17:28:19 -0400
ActionableScore: 7
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
ARM FF-A notification handlers can dereference a notifier entry after concurrent unregister frees it, creating a race-based UAF in callback dispatch that can cause kernel DoS and may have higher impact if freed callback state is reused.

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

The original Linux kernel CVE announcement for CVE-2026-64080 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64080

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-64080	MODERATE	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'ARM FF-A notification handlers could look up a notifier entry under notify_lock, drop the lock, and then dereference the saved entry after a concurrent unregister freed it. This creates a race based use-after-free window in both normal and framework notification callback paths. The affected object contains callback function pointers and callback data, so the bug is more serious than a simple crash if freed memory can be reused in a controlled way. For the CVSS the PR:L is used in the paranoid score because a reduced privilege local service or delegated device management path may be enough on some systems to trigger notifier unregister or FF-A client lifecycle changes, while reliable triggering still depends on platform specific FF-A clients. The issue is not network reachable. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality, integrity, and availability impact due to use-after-free of callback state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6)  SKIP CVE-2026-64080 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	LOCK UAF LINUS KPANIC 	-	-	checked

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

ActionableScore=7
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**

## 2. Signal breakdown

Paranoid scoring signals:

* Firmware-mediated external influence: +1
  FF-A notifications are delivered through firmware or secure-world mediated paths, not through a normal network socket.

* Memory corruption, strong corruption primitive: +2
  The patch fixes a real use-after-free window where `notifier_cb_info` may be freed after lookup and then dereferenced.

* Real lifetime corruption: +1
  This is a stale pointer after concurrent unregister/free.

* Reliable kernel crash / strong DoS: +1
  Dereferencing freed callback state can realistically crash the kernel.

* Privilege escalation plausible: +2
  The stale object contains callback function pointers and callback data. No exploit primitive is demonstrated, but callback dispatch from freed state is a high-risk UAF pattern.

* Privileged kernel/device-management memory corruption path: +1
  The corruption occurs in a firmware notification subsystem and involves trusted callback dispatch state.

* Hard or unreliable race / special timing required: -1
  Triggering depends on racing notification handling against unregister.

Conservative score is lower because typical reliable triggering likely requires privileged control over FF-A notifier lifecycle or device/service teardown, so admin or privileged-service assumptions reduce practical exploitability.

## 3. Reachability analysis

The issue is not network reachable. It is reachable through ARM FF-A notification handling when a notifier callback is looked up while another path unregisters and frees the same notifier entry.

A normal remote attacker cannot directly trigger this. Practical triggering likely requires one of: control over an FF-A client lifecycle, a privileged local service interacting with FF-A devices, firmware or secure-world notification influence, or platform-specific driver teardown behavior.

Namespaces and containers probably do not make this broadly unprivileged by default. However, reduced-privilege service accounts or delegated device-management paths may lower the effective privilege requirement on some systems. The path is relevant only on systems using ARM FF-A firmware support.

Call-site confidence: high. The patch shows both lookup and post-unlock dereference sites.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because it is a real race-based UAF involving callback pointers and callback data. The realistic impact may often be DoS due to the race and platform-specific triggering requirements.

The theoretical worst case is more serious because freed callback state may be reused before dispatch, creating a plausible path toward control-flow or callback-data misuse. There is no demonstrated arbitrary write or working LPE chain in the patch, so the conservative score remains lower, but the bug should not be auto-closed.

## 5. One-sentence report phrase

ARM FF-A notification handlers can dereference a notifier entry after concurrent unregister frees it, creating a race-based UAF in callback dispatch that can cause kernel DoS and may have higher impact if freed callback state is reused.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the bug is a real UAF race involving callback function pointers and callback data in a firmware notification path. Even though practical triggering is platform-dependent and likely not remotely reachable, the callback-dispatch primitive is important enough for manual review.

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

Patch: firmware: arm_ffa: Snapshot notifier callbacks under lock [ Upstream
Commit: d1e38551fadea230649bc428f0f35c9ee062a072
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d1e38551fadea230649bc428f0f35c9ee062a072

Changed files:
  drivers/firmware/arm_ffa/driver.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=d1e38551fadea230649bc428f0f35c9ee062a072

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

The original Linux kernel CVE announcement for CVE-2026-64080 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64080

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: 4
  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).