[CVE-2026-53286][MODERATE 7.0] idpf: fix double free and use-after-free in aux device error paths

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

CVE: CVE-2026-53286
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: idpf: fix double free and use-after-free in aux device error paths
Commit: 722b91d5086a249318c9d0e2b36aeac80ba8c808
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=722b91d5086a249318c9d0e2b36aeac80ba8c808
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53286
Analysis date: Fri, 26 Jun 2026 17:02:46 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A UAF and double-free in the idpf RDMA auxiliary-device error path can occur when `auxiliary_device_add()` fails, because the release callback frees `iadev` before the fall-through path reuses and frees it again, leading to local DoS and requiring manual review for possible memory-corruption impact.

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

The original Linux kernel CVE announcement for CVE-2026-53286 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53286

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-2026-53286	MODERATE	CHECK	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-415;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A use-after-free and double-free can occur in the idpf auxiliary device error path when auxiliary_device_add fails during RDMA vport or core auxiliary device setup. auxiliary_device_uninit can drop the final device reference and invoke the release callback that frees iadev, but the old fall-through path then reads adev id from the freed object and frees iadev again. For the CVSS the PR:L is used for the paranoid score because a delegated service account, reduced-capability root, or containerized network management role may be able to trigger driver recovery or device setup paths without full host administration. The issue is local and not directly network reachable through packet traffic. Impact is at least denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to kernel memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE DANGER INIT ERRORPATH UAF NETWORK HARDWARE  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: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, strong corruption primitive: +2. The patch fixes an explicit UAF and double-free after `auxiliary_device_uninit()` invokes the release callback and frees `iadev`.
* Real lifetime corruption: +1. This is a device lifetime ordering bug involving `put_device()`, release callbacks, stale `adev` access, and second free.
* Reliable kernel crash / strong DoS: +1. Double-free or UAF in this path can realistically crash the kernel.
* Privileged kernel/device-management memory corruption path: +1. The corruption occurs in a trusted driver auxiliary-device setup path.
* Requires admin/root/CAP-level control in typical deployments: -2. Triggering generally requires driver probe, recovery, RDMA auxiliary device setup, or controlled failure of `auxiliary_device_add()`.
* Conservative total: 3.

Paranoid additional interpretation:

* Local unprivileged or reduced-privilege trigger concern: +1. In some deployments, a delegated service account, container root, or network-management component may influence device recovery or setup paths without full host-root equivalence.
* Weak LPE concern: +1. UAF plus double-free is a plausible kernel memory corruption class, but no attacker-controlled reclaim, overwrite target, callback control, or type confusion is demonstrated.
* Special/error-path triggering constraint: -1. The bug requires `auxiliary_device_add()` failure in a specific probe/setup error path.
* Constrained primitive uncertainty: -1. The patch shows stale read of `adev->id` and double-free, but does not show controlled payload or controlled object replacement.
* Paranoid total: 5.

## 3. Reachability analysis

The bug is local and not directly network-triggerable through packet traffic. The affected path is in Intel `idpf` RDMA auxiliary device creation during vport or core auxiliary-device setup. Realistic triggering likely depends on driver load, probe, recovery, RDMA auxiliary support, device state, or an error condition in `auxiliary_device_add()`.

In typical deployments this is privileged because ordinary users cannot directly force driver auxiliary-device registration failures. However, the paranoid interpretation should consider reduced-capability root, containerized management agents, or delegated network/device-management services that can influence driver recovery or device setup without being equivalent to full host root.

## 4. Severity interpretation

This is not an ordinary Moderate cleanup bug because the commit explicitly describes both UAF and double-free. The realistic impact is most likely local kernel crash or system instability from a driver error path. Practical privilege escalation is not demonstrated, because the patch does not show attacker-controlled reclaim, object replacement, arbitrary write, callback hijack, or type confusion.

The conservative handling is borderline manual review. The paranoid handling is Actionable Moderate at minimum because kernel lifetime corruption in a privileged device-management path is historically easy to underestimate.

## 5. One-sentence report phrase

A UAF and double-free in the idpf RDMA auxiliary-device error path can occur when `auxiliary_device_add()` fails, because the release callback frees `iadev` before the fall-through path reuses and frees it again, leading to local DoS and requiring manual review for possible memory-corruption impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED.

Reason: explicit kernel UAF plus double-free in a driver lifetime path. Even though the trigger is constrained and likely privileged, the bug class is memory corruption and should not be auto-closed without human review.

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

Patch: idpf: fix double free and use-after-free in aux device error paths
Commit: 722b91d5086a249318c9d0e2b36aeac80ba8c808
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=722b91d5086a249318c9d0e2b36aeac80ba8c808

Commit description:

When auxiliary_device_add() fails in idpf_plug_vport_aux_dev() or
idpf_plug_core_aux_dev(), the err_aux_dev_add label calls
auxiliary_device_uninit() and falls through to err_aux_dev_init.  The
uninit call will trigger put_device(), which invokes the release
callback (idpf_vport_adev_release / idpf_core_adev_release) that frees
iadev.  The fall-through then reads adev->id from the freed iadev for
ida_free() and double-frees iadev with kfree().

Free the IDA slot and clear the back-pointer before uninit, while adev
is still valid, then return immediately.

Commit 65637c3 ("idpf: fix UAF in RDMA core aux dev deinitialization")
fixed the same use-after-free in the matching unplug path in this file but
missed both probe error paths.

Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: stable@kernel.org
Fixes: be91128 ("idpf: implement RDMA vport auxiliary dev create, init, and destroy")
Fixes: f4312e6 ("idpf: implement core RDMA auxiliary dev create, init, and destroy")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260506-jk-iwl-net-2026-05-04-v2-4-a5ea4dc837a9@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/intel/idpf/idpf_idc.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=722b91d5086a249318c9d0e2b36aeac80ba8c808

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

The original Linux kernel CVE announcement for CVE-2026-53286 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53286

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.
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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
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