[CVE-2026-97595][MODERATE 7.0] mac802154: fix use-after-free of sdata via queued RX frames

[CVE-2026-97595][MODERATE 7.0] mac802154: fix use-after-free of sdata via queued RX frames

[AL-KERNEL]

CVE: CVE-2026-97595
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: mac802154: fix use-after-free of sdata via queued RX frames
Commit: 4740ef0518c5e3bf31ebfb2288a6ac3b462ead06
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4740ef0518c5e3bf31ebfb2288a6ac3b462ead06
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97595
Analysis date: Fri, 25 Sep 2026 07:26:55 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97595 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97595

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-2026-97595	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97595 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.5';DESCR 'mac802154 queues beacon and MAC command frames while retaining raw sdata and skb dev pointers without holding a netdev reference. A queued worker can dereference the interface after teardown has freed its private data, producing a confirmed slab use after free. Concurrent list insertion from RX softirq and deletion by process context workers can also corrupt the shared RX lists. An adjacent attacker may contribute to the trigger by flooding crafted or repeated IEEE 802.15.4 MAC command or beacon frames while the affected interfaces are active or being removed. For the CVSS the PR:N is selected because a radio adjacent sender does not need a local account or privileges on the target. AV:A is used because exploitation requires access to the local IEEE 802.15.4 communication environment rather than general Internet reachability. AC:H reflects the required timing between frame reception, deferred worker execution, and interface teardown or concurrent list access. Impact is at least denial of service through a kernel crash or stalled interface removal. The confirmed UAF and possible list corruption may also permit confidentiality or integrity impact and should be reviewed for potential privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)  SKIP CVE-2026-97595 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	REMOTE READ LOCK DANGER INIT UAF SKB HARDWARE LINUS KPANIC  DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH	-	-	checked

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

ActionableScore=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 4
* Conservative score: 5
* Raw paranoid score: 4
* Paranoid score: 5
* Applied conservative floor: 4 -> 5 under REAL UAF FLOOR 5 because attacker-influenced queued frames reach nontrivial active MAC processing through a stale structured interface object rather than only a cleanup dereference.
* Applied paranoid floor: 4 -> 5 for the same established active-processing surface. No speculative reclaim or LPE point was added.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Positive signals:

* +2 Real UAF. A queued frame retains raw `sdata` and `skb->dev` references after interface removal can free the associated `net_device` private data. KASAN confirms the post-lifetime read.
* +1 Reliable kernel crash or strong DoS. The confirmed slab UAF in a worker can produce an Oops or kernel failure.
* +1 Independent list-corruption candidate. Unlocked `list_add_tail()` in softirq context races with worker or flush-side `list_del()`, potentially corrupting the shared active RX lists.
* Floor 5 applies because the stale `sdata` is an active structured object used by normal RX workers. MAC-command processing can inspect interface state and initiate protocol processing before releasing the queued frame.

Negative signals:

* No negative privilege penalty. Host-admin-equivalent privilege for the complete trigger is not positively established.
* No race penalty. Flooding can repeatedly populate the queues, and the evidence does not establish a narrow, one-shot, externally uncontrollable race.
* No rare-hardware penalty. IEEE 802.15.4 support is specialized, but the supplied evidence does not establish a physical-only or sufficiently rare requirement.

Material signals not awarded:

* Controlled reclaim or attacker-shaped replacement data is not demonstrated.
* Arbitrary or directed kernel read/write is not demonstrated.
* Strong LPE leverage is not awarded merely from the UAF or list corruption.
* Structured stale-object leverage is not separately awarded because attacker control over reclaimed `sdata` contents or replacement is not established.
* Direct network-reachability points are withheld because the complete UAF sequence includes interface teardown and the supplied evidence does not show that a radio-adjacent attacker controls that operation.
* Confidentiality and integrity points are not awarded because no disclosure, protected-state modification, or practical privilege-escalation chain is established.
* No extra Availability point is awarded because it would duplicate the same UAF-induced crash.
* No concrete repeated release or refcount operation exists. The first lifetime-ending event is interface removal, but the later worker performs a stale dereference rather than a second `put`, `free`, or refcount mutation. The dedicated repeated-release point and paranoid repeated-refcount point are therefore withheld.

3. Reachability analysis

A radio-adjacent actor can supply beacon or MAC-command frames and can increase queue pressure by flooding an active IEEE 802.15.4 interface. The reproduced UAF also requires interface removal while queued work remains, but the evidence does not establish whether the same below-host-admin principal can perform that removal.

The privilege boundary is therefore unresolved. Interface teardown commonly passes through network-device control paths, but the exact capability check and governing user namespace are not supplied. The presence of networking code does not prove that an attacker-created user or network namespace can perform the complete RX, teardown, and stale-worker sequence.

`HostAdminRequired=UNKNOWN` and `NamespaceScopedPrivilege=UNKNOWN` are consequently appropriate. Existing IEEE 802.15.4 interface and PHY setup is a prerequisite. No sysctl or boot-parameter prerequisite is shown. The list race may also occur independently between asynchronous producers and consumers on a configured PHY, but reliable below-host-admin triggering of that complete corruption path is not established.

4. Primitive and severity interpretation

The primary primitive is a confirmed post-lifetime read from freed `net_device` private storage through queued `sdata` or `skb->dev`. The stale target is an active structured interface object, not a fixed transfer buffer. Its use occurs in normal deferred RX processing, including MAC-command and beacon handling, rather than solely in a destructor.

A second independent defect allows concurrent mutation of unprotected kernel lists. This establishes possible list corruption but not controlled pointer corruption or arbitrary write.

There is no concrete repeated release or refcount mutation. Interface removal may end the object lifetime, but the stale worker reads or processes the object rather than applying a second lifetime operation to the same reference.

The issue is therefore CLASS_B, not CLASS_A. Demonstrated consequences are KASAN-detected UAF, likely kernel crash, list corruption, and possible delayed interface teardown. Privilege escalation remains speculative because controlled reclaim, replacement contents, callback influence, and directed read/write are absent.

`ImportantCandidate=YES` reflects the combination of a confirmed active-object UAF, attacker-influenced RX work, and an independent shared-list corruption mechanism whose exploitation leverage requires source-level review. `AutoDowngradeAllowed=NO` because automatically reducing this to an ordinary crash-only issue would discard unresolved active-processing and list-corruption behavior. The likely operational severity is Actionable Moderate, with Important classification dependent on reachability and reclaim analysis.

5. One-sentence report phrase

A confirmed mac802154 interface UAF and concurrent RX list corruption can be reached when queued attacker-influenced IEEE 802.15.4 frames overlap interface teardown, causing at least kernel denial of service and requiring manual review for unresolved exploitation leverage.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Review should determine whether a below-host-admin or radio-adjacent actor can complete the teardown race, whether corrupted RX list pointers provide a useful write primitive, and whether freed `sdata` storage can be predictably reclaimed before worker processing.

7. Call-site confidence

Call-site confidence: high

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

Patch: mac802154: fix use-after-free of sdata via queued RX frames
Commit: 4740ef0518c5e3bf31ebfb2288a6ac3b462ead06
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4740ef0518c5e3bf31ebfb2288a6ac3b462ead06

Commit description:

The RX softirq producer ieee802154_subif_frame() queues received beacon
and MAC-command frames onto local->rx_beacon_list / rx_mac_cmd_list and
schedules a process-context worker, storing a raw mac_pkt->sdata (and
skb->dev == sdata->dev) with neither a reference nor any locking:

 - the lists have no lock: the softirq producer list_add_tail()s while the
   mac_wq worker list_del()s, so sibling interfaces on the same phy corrupt
   the list;

 - the workers dereference the interface after it may have been freed.
   mac802154_rx_mac_cmd_worker() touches mac_pkt->sdata directly, and
   mac802154_rx_beacon_worker() -> mac802154_process_beacon() dereferences
   skb->dev (== sdata->dev). Removing an interface frees its sdata
   (netdev_priv) while a queued frame still points at it, so a later worker
   run is a use-after-free.

Reproduced under KASAN by flooding a victim interface with MAC command
frames and removing it (the beacon path is the same class via skb->dev):

  BUG: KASAN: slab-use-after-free in mac802154_rx_mac_cmd_worker+0x463/0x630 [mac802154]
  Read of size 4 at addr ffff888002f9ea18 by task kworker/u8:1/31
  Workqueue: phy0-mac-cmds mac802154_rx_mac_cmd_worker [mac802154]
  Call Trace:
   mac802154_rx_mac_cmd_worker+0x463/0x630 [mac802154]
   process_one_work+0x611/0xe80
   worker_thread+0x52e/0xdc0
   kthread+0x30c/0x630
   ret_from_fork+0x2fd/0x3e0

Fix both lists together:

 - add local->rx_lock and take it around every list access: the softirq
   producer (plain spin_lock, softirq context) and the workers and flush
   (spin_lock_bh, process context);

 - pin the interface for the lifetime of a queued frame with
   netdev_hold()/netdev_put(), so the worker can safely dereference sdata /
   skb->dev even while the interface is being removed;

 - dequeue under the lock at the head and loop-drain the whole list in the
   workers (they previously processed one frame per run and relied on a
   later enqueue to drain the rest);

 - drop not-yet-started frames of an interface before it is unregistered,
   from ieee802154_if_remove() (after the RCU grace period) and from the
   ieee802154_remove_interfaces() loop -- the latter is the whole-phy
   teardown path, which does not go through ieee802154_if_remove().

An in-flight worker that already dequeued a frame keeps its own netdev
reference; unregister_netdevice() then waits it out in netdev_run_todo(),
which runs at rtnl_unlock() (rtnl released) and after the interface has
been closed, so it does not pin rtnl. A worker blocked in an association
TX only delays that one interface's unregister (the usual "waiting for %s
to become free"), it does not hold rtnl. netdev_hold() is used for this
reason instead of a cancel_work_sync() under rtnl, which would block on
the worker's unbounded MLME TX wait via ieee802154_sync_queue().

The mac-command worker additionally skips processing for a stopped
interface (ieee802154_sdata_running()), avoiding a needless association
response during teardown.

Fixes: 57588c7 ("mac802154: Handle passive scanning")
Cc: stable@vger.kernel.org
Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Assisted-by: AuditCode-AI:2026.07
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/20260725135154.99876-1-security@auditcode.ai
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  include/net/cfg802154.h
  net/mac802154/ieee802154_i.h
  net/mac802154/iface.c
  net/mac802154/main.c
  net/mac802154/rx.c
  net/mac802154/scan.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=4740ef0518c5e3bf31ebfb2288a6ac3b462ead06

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

The original Linux kernel CVE announcement for CVE-2026-97595 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97595

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:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.5

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: unknown
  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: 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).