[CVE-2026-45996][MODERATE REGULAR] spi: imx: fix use-after-free on unbind

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

CVE: CVE-2026-45996
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: spi: imx: fix use-after-free on unbind
Commit: f99165ef067723221472ce1aff632bc74f562643
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f99165ef067723221472ce1aff632bc74f562643
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45996
Analysis date: Wed, 27 May 2026 17:36:13 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-45996 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45996

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 REGULAR
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-2026-45996	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-416;*CWE-664;*CWE-672;CWE-703;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.7';DESCR 'spi_imx_remove() can keep using spi_imx driver data after spi_unregister_controller() has deregistered and potentially freed the controller and its subsystem allocated private data. This creates a use after free during driver unbind or remove, with later runtime PM and SDMA cleanup touching freed memory. For the CVSS the PR:H is used because reliable triggering normally requires administrator level device management such as platform driver unbind or module removal. The issue is not network reachable and is not exposed through a normal user data path. Impact is mainly local denial of service during device removal, with higher confidentiality and integrity impact kept only for the paranoid score because the bug class is UAF in kernel driver cleanup.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3) 	MAYBE	UAF HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3

1. ActionableScore
* Conservative score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended**::

2. Signal breakdown
* Generic memory corruption: +2. The patch fixes a real use-after-free of `spi_imx` / controller private data after `spi_unregister_controller()`.
* Real lifetime corruption: +1. The root cause is object lifetime mismatch during controller deregistration and later driver cleanup.
* Reliable kernel crash / DoS: +1. Accessing freed driver data during unbind can crash the kernel.
* Requires admin/root/device-management control: -2. Reliable triggering normally requires platform driver unbind, module removal, or equivalent device-management privilege.
* Rare hardware/configuration exposure: -1. The affected path is specific to i.MX SPI controller hardware and the remove/unbind path.
* No remote or normal unprivileged data path. No evidence of attacker-controlled payload, reclaim primitive, or practical LPE is shown.

3. Reachability analysis
The bug is reachable during i.MX SPI driver remove or unbind. In typical deployments, only an administrator or host-level device manager can trigger this path. Containers generally do not lower privileges unless they are granted dangerous device-management access. The issue is not network reachable and is not triggered through ordinary SPI user I/O. Exploitation beyond crash would require control over timing and freed-object reuse in a privileged cleanup path, which is not demonstrated.

4. Severity interpretation
This is a real UAF, so it should not be dismissed solely as a cleanup bug. However, it behaves more like a privileged device-management DoS than an Important-class LPE because the trigger normally requires admin-level unbind/removal and the patch does not show a controlled reclaim or overwrite primitive. It is borderline and worth manual awareness, but not a strong Important candidate.

5. One-sentence report phrase
The i.MX SPI remove path can use controller private data after `spi_unregister_controller()` frees it, causing a privileged unbind-time UAF and potential kernel crash.

6. Manual review recommendation
MANUAL CHECK RECOMMENDED. The bug class is UAF, but practical exposure is limited to privileged i.MX SPI device unbind or removal with no demonstrated unprivileged or remote trigger.

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

Patch: spi: imx: fix use-after-free on unbind
Commit: f99165ef067723221472ce1aff632bc74f562643
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f99165ef067723221472ce1aff632bc74f562643

Commit description:

The SPI subsystem frees the controller and any subsystem allocated
driver data as part of deregistration (unless the allocation is device
managed).

Take another reference before deregistering the controller so that the
driver data is not freed until the driver is done with it.

Fixes: 307c897 ("spi: spi-imx: replace struct spi_imx_data::bitbang by pointer to struct spi_controller")
Cc: stable@vger.kernel.org	# 5.19
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20260324082326.901043-2-johan@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/spi/spi-imx.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=f99165ef067723221472ce1aff632bc74f562643

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

The original Linux kernel CVE announcement for CVE-2026-45996 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45996

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:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.7

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: unknown
  Paranoid ActionableScore: 3

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 REGULAR

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).