[CVE-2026-80564][LOW] gve: fix NULL dereference due to missing ptp adjfine

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

CVE: CVE-2026-80564
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: gve: fix NULL dereference due to missing ptp adjfine
Commit: e9482feeed66d4bc805458631013e9b61b1a9eaf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9482feeed66d4bc805458631013e9b61b1a9eaf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80564
Analysis date: Wed, 26 Aug 2026 13:16:20 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A missing `adjfine` callback in the gve PTP clock implementation allows a local privileged or delegated time-management user to trigger a NULL function pointer dereference via `clock_adjtime()`, causing a kernel crash or oops without evidence of privilege escalation or data exposure.

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

The original Linux kernel CVE announcement for CVE-2026-80564 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80564

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-80564	LOW	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:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A NULL function pointer dereference in the gve PTP clock path occurs because the ptp_clock_info structure did not provide an adjfine callback while ptp_clock_adjtime can call that operation for frequency adjustment requests. A local actor can trigger this through clock_adjtime on the exposed /dev/ptp device, for example with a PTP test tool requesting frequency adjustment. For the CVSS the PR:L is used only for the paranoid score because some deployments may delegate CAP_SYS_TIME or PTP control to a reduced privilege service account, while the typical base case requires administrative privileges. The issue is not network reachable and is triggered through a local device or syscall interface rather than packet processing. Impact is denial of service via kernel NULL dereference and possible kernel crash. There is no supported confidentiality or integrity impact because the primitive is a NULL callback call, not UAF, OOB access, info leak, or arbitrary write.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-80564 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	REMOTE DANGER NULLPTR SIMPLEFIX NETWORK HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Reliable kernel crash / strong DoS: +1. The commit shows a direct NULL function pointer dereference through `ptp_clock_adjtime()`.
* Requires admin/root/CAP_SYS_TIME in typical deployments: -2. The reproducer uses `sudo`, and clock adjustment normally requires elevated time-management privilege.
* Rare/device-specific exposure: -1. The affected path requires the Google `gve` driver with PTP device support exposed as `/dev/ptpX`.

Conservative raw score is negative, clamped to 0.

Paranoid signals:

* Reliable kernel crash / strong DoS: +1. The trigger is simple once the caller has permission to issue the PTP adjustment request.
* No memory-corruption or LPE bonus. The primitive is a NULL callback call, not UAF, OOB access, object reuse, arbitrary write, or refcount corruption.
* No remote/network bonus. This is reached through a local syscall/device path, not packet processing.

## 3. Reachability analysis

The bug can be triggered locally through `clock_adjtime()` against the affected PTP device. In normal deployments this requires root or `CAP_SYS_TIME`, so it is not a true unprivileged local trigger. A paranoid interpretation can lower practical privilege expectations if a service account, container root, or reduced-capability process is intentionally delegated PTP or time-adjustment access, but that still does not create a memory-corruption primitive. The path is not network-reachable and depends on systems using the `gve` driver with PTP support enabled.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like kernel DoS issue. The realistic impact is a local crash or oops through a missing callback. There is no evidence of confidentiality impact, integrity impact, privilege escalation, UAF, stale object reuse, callback control by attacker data, or arbitrary write. The paranoid score remains low because the only elevated concern is that delegated PTP/time privileges may make triggering easier in some environments.

## 5. One-sentence report phrase

A missing `adjfine` callback in the gve PTP clock implementation allows a local privileged or delegated time-management user to trigger a NULL function pointer dereference via `clock_adjtime()`, causing a kernel crash or oops without evidence of privilege escalation or data exposure.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be autoclosable in most triage flows because it is a device-specific local DoS with a NULL dereference only, no network reachability, and no supported memory-corruption or privilege-escalation path.

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

Patch: gve: fix NULL dereference due to missing ptp adjfine
Commit: e9482feeed66d4bc805458631013e9b61b1a9eaf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9482feeed66d4bc805458631013e9b61b1a9eaf

Commit description:

Fix NULL dereference due to missing implementation of adjfine, which can
be triggered from usermode as follows:

sudo ./testptp -d /dev/ptp0 -f 0
[  551.943697] BUG: kernel NULL pointer dereference, address: 0000000000000000
[...]
[  552.061946] Call Trace:
[  552.064487]  <TASK>
[  552.066681]  ptp_clock_adjtime+0x1c0/0x2c0
[  552.070874]  ? get_clock_desc+0x6b/0xb0
[  552.074825]  pc_clock_adjtime+0x78/0xc0
[  552.078755]  __do_sys_clock_adjtime+0x85/0x110
[  552.083293]  do_syscall_64+0xea/0x610

Cc: stable@vger.kernel.org
Fixes: acd1638 ("gve: Add initial PTP device support")
Signed-off-by: Jordan Rhee <jordanrhee@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20260807224315.234152-3-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/google/gve/gve_ptp.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=e9482feeed66d4bc805458631013e9b61b1a9eaf

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

The original Linux kernel CVE announcement for CVE-2026-80564 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80564

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: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: 0
  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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).