[CVE-2026-89854][MODERATE 7.0] scsi: qla2xxx: Fix cs84xx use-after-free on host teardown

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

CVE: CVE-2026-89854
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: scsi: qla2xxx: Fix cs84xx use-after-free on host teardown
Commit: 8c1ebcade6aac58137f2645b579894301febabf3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c1ebcade6aac58137f2645b579894301febabf3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89854
Analysis date: Wed, 16 Sep 2026 12:23:26 -0400
ActionableScore: 4
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
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The original Linux kernel CVE announcement for CVE-2026-89854 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89854

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-2026-89854	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-89854 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-362;CWE-367;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '5.8';DESCR 'A use after free exists in the qla2xxx teardown path because ha cs84xx can be released before the 84xx_fw_version sysfs attribute is removed. A concurrent local read of qla24xx_84xx_fw_version_show() can dereference the freed object during the window between qla84xx_put_chip() and scsi_remove_host(), causing a kernel crash or exposing stale data from reused memory. For the CVSS the PR:L is used in the paranoid scenario because a local user may be able to read the host sysfs attribute while teardown is triggered by hotplug, PCI error handling, or an administrative management action. The issue is not network reachable and requires local interaction with sysfs plus a teardown race. Impact is at least local denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to use after free and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4)	YES	UAF HARDWARE LINUS KPANIC 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 4
* Applied conservative floor/cap: Real UAF floor 4 applied because a real stale object dereference is established and host-admin-only reachability is not positively proven.
* Raw paranoid score: 3
* Paranoid score: 4
* Applied paranoid floor/cap: Real UAF floor 4 applied. Floor 5 not applied because no controlled reclaim, no repeated lifetime/refcount mutation, and no strong post-free exploitation leverage is established.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

Conservative signals:

* +2 Real UAF / lifetime violation: qla84xx_put_chip() can drop the last reference and free ha->cs84xx while ha->cs84xx remains reachable through the host sysfs attribute path.
* +1 Reliable kernel crash / strong DoS: a concurrent 84xx_fw_version sysfs read can dereference freed memory in qla24xx_84xx_fw_version_show(), plausibly causing Oops or kernel crash.
* -1 Hard timing / teardown race: the reader must hit the narrow window between qla84xx_put_chip() and scsi_remove_host(), during host teardown or PCI error handling.

Paranoid additional signal:

* +1 Confidentiality plausible: the stale object is read through a sysfs show path that returns formatted data to userspace, so limited stale-data exposure is technically plausible if the freed object is reused before the read completes.

Important non-awarded signals:

* +2 Strong exploitation leverage not awarded: no controlled reclaim, controlled replacement object, arbitrary write, callback control, or refcount takeover is established.
* +1 Structured stale-object leverage not awarded: stale use is a sysfs show dereference, not demonstrated nontrivial post-reuse structured processing.
* +1 Concrete repeated release/refcount not awarded: the second operation is a stale dereference/read, not a second put/release/refcount mutation.
* Weak LPE not awarded: UAF alone is not enough, and no privilege-escalation primitive is shown.
* Extra Availability not awarded: the same crash is already counted once.
* Integrity not awarded: no unauthorized write or policy modification is established.
* Remote reachability not awarded: this is local sysfs plus teardown behavior, not packet or remote protocol input.
* Host-admin penalty not awarded: complete host-admin-only triggering is not positively established.
* Rare hardware penalty not awarded: qla2xxx/cs84xx hardware is specialized, but the prompt requires concrete evidence before applying this as a reducing signal.

Repeated release/refcount check:

* First release can end lifetime: yes. qla84xx_put_chip() may drop the last reference and free ha->cs84xx through __qla84xx_chip_release().
* Exact same reference survives: yes. ha->cs84xx is not cleared before the sysfs attribute is removed.
* Second operation is a real lifetime/refcount mutation: no. qla24xx_84xx_fw_version_show() dereferences the stale pointer but does not perform a second put/release/refcount operation.
* +1 Concrete repeated release/refcount awarded: no.
* Paranoid repeated-refcount leverage +1 awarded: no.
* FLOOR 5 applied: no.

3. Reachability analysis

The directly exposed operation is a local read of the SCSI host sysfs attribute 84xx_fw_version. Such sysfs attributes are commonly readable by local users, but the supplied evidence does not fully prove permissions for this exact attribute.

The freeing side occurs during qla2x00_remove_one() or qla2x00_disable_board_on_pci_error(), i.e. host teardown, device removal, or PCI error handling. A local unprivileged user may be able to race a sysfs read while teardown is triggered by an administrator, hotplug, device failure, or management service, but the supplied evidence does not establish that the same unprivileged attacker can reliably trigger the complete teardown sequence.

HostAdminRequired is therefore UNKNOWN, not YES and not NO. NamespaceScopedPrivilege is NO because the relevant device/sysfs teardown path is not shown to be namespace-scoped. There is no network trigger. There is a real race, and the race looks like a narrow teardown window rather than a repeatedly attacker-driven create/free loop.

4. Primitive and severity interpretation

The exact primitive is a real use-after-free of ha->cs84xx. The object is an active structured driver object, not merely a fixed DMA buffer. The stale use occurs through a sysfs show callback after the object may have been freed but before scsi_remove_host() removes the attribute and drains in-flight kernfs operations.

This is closer to an ordinary stale sysfs dereference than to a repeated lifetime/refcount corruption case. The first lifetime operation may free the object, but the later stale operation only reads/dereferences it. It does not perform a second lifetime mutation.

PrimitiveClass is CLASS_B because a real kernel lifetime violation exists. It is not CLASS_A because controlled reclaim, arbitrary read/write, callback control, refcount takeover, or demonstrated LPE is not established. Demonstrated consequence is local DoS via kernel crash. Paranoid consequence is limited stale-data disclosure through sysfs read-back. Privilege escalation remains speculative and is not scored.

ImportantCandidate is NO because this appears to be a constrained teardown/sysfs UAF with no demonstrated strong exploitation leverage beyond crash and possible limited disclosure. ManualReview is RECOMMENDED because it is still a real UAF in kernel driver state. AutoDowngradeAllowed is YES because no concrete repeated refcount mutation, boundary bypass, controlled corruption, or unresolved strong exploitation primitive is established.

5. One-sentence report phrase

A qla2xxx teardown ordering bug can free ha->cs84xx before the 84xx_fw_version sysfs attribute is removed, allowing a concurrent local sysfs read to dereference freed memory and cause a kernel crash, with limited stale-data exposure possible in the paranoid interpretation.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a real UAF with a user-visible sysfs read path, but the demonstrated primitive is constrained to a teardown race and lacks controlled reclaim, arbitrary write, repeated refcount mutation, or a proven LPE path.

7. Call-site confidence

Call-site confidence: high

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

Patch: scsi: qla2xxx: Fix cs84xx use-after-free on host teardown
Commit: 8c1ebcade6aac58137f2645b579894301febabf3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c1ebcade6aac58137f2645b579894301febabf3

Commit description:

qla84xx_put_chip() drops the last reference to ha->cs84xx and frees it via
__qla84xx_chip_release() without clearing ha->cs84xx. During teardown it ran
before scsi_remove_host(), which is what removes the 84xx_fw_version host
sysfs attribute. A concurrent read of that attribute in the window between
the two calls executes qla24xx_84xx_fw_version_show(), which dereferences
the freed ha->cs84xx, resulting in a use-after-free.

Move qla84xx_put_chip() to after scsi_remove_host() in both
qla2x00_remove_one() and qla2x00_disable_board_on_pci_error(). Once
scsi_remove_host() returns, the sysfs attribute is gone and kernfs has
drained any in-flight show(), so no reader can touch cs84xx; the put still
runs before the host and ha are freed.

Fixes: fe1b806 ("[SCSI] qla2xxx: Refactor shutdown code so some functionality can be reused.")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-dev@google.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Link: https://patch.msgid.link/20260730155838.2119230-7-njavali@marvell.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/scsi/qla2xxx/qla_os.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=8c1ebcade6aac58137f2645b579894301febabf3

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

The original Linux kernel CVE announcement for CVE-2026-89854 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89854

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:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 4

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).

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