[CVE-2026-89843][MODERATE 7.0] scsi: qla2xxx: Zero-init bsg stack buffers to avoid info leak

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

CVE: CVE-2026-89843
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: scsi: qla2xxx: Zero-init bsg stack buffers to avoid info leak
Commit: 1c820d0900e4aacd5020b989159f6b4b2f7d0d6a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1c820d0900e4aacd5020b989159f6b4b2f7d0d6a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89843
Analysis date: Wed, 16 Sep 2026 11:36:26 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89843 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89843

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-2026-89843	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-89843 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L';*CWE-457;CWE-908;*CWE-200;CWE-201;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '6.6';DESCR 'An uninitialized stack buffer in qla2xxx BSG handlers can expose stale kernel stack bytes to user space when a short request payload is copied into a 256 byte buffer and a full reply structure is copied back. The confirmed leak paths are qla2x00_read_fru_status() and qla2x00_read_i2c(), while write or update paths may also pass uninitialized fields to the device. For the CVSS the PR:L because the attacker needs local access to the qla2xxx BSG device node or equivalent SCSI BSG permissions, but does not need kernel privileges. The issue is not network reachable and requires a local process on a system with the affected qla2xxx driver and exposed BSG interface. Impact is at least local information disclosure of kernel stack data. In the paranoid interpretation, repeated stack disclosure may help bypass kernel mitigations or expose sensitive values, and limited integrity or availability impact is possible through uninitialized fields sent to the device.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate (with actual score 5)	YES	SIMPLEFIX LEAK HARDWARE LINUS KPANIC MEMORY 	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 5
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate**::

No floor or cap was applied. The paranoid score is emitted as ActionableScore because repeated local kernel stack disclosure is a defensible higher triage interpretation.

2. Signal breakdown

Conservative positive signals:

* +2: User-visible kernel stack disclosure is directly established. qla2x00_read_fru_status() and qla2x00_read_i2c() can copy a full reply structure back to userspace after only a short user request initialized part of the 256 byte stack buffer.
* +1: Confidentiality impact is concrete. Stale kernel stack bytes are copied to userspace through sg_copy_from_buffer().
* +1: Practical trigger-to-disclosure chain is directly described. A short BSG request leaves part of the stack buffer uninitialized and the read reply path returns that stale data.

Paranoid additional signal:

* +1: Repeated disclosure may expose useful kernel stack values over multiple calls, including pointers or other mitigation-relevant data. This is still scored as disclosure leverage, not as memory corruption or LPE.

Non-awarded signals:

* RealUAF not awarded. No use-after-free or stale post-lifetime object use is established.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Integrity impact not awarded conservatively. The write/update paths may pass uninitialized fields to the device, but no concrete unauthorized kernel-state modification is shown.
* Availability impact not awarded. No crash, panic, or resource exhaustion is established.
* Remote reachability not established. This is a local BSG interface issue.
* Strong LPE not awarded. Kernel stack disclosure may assist exploitation of other bugs, but this patch does not establish a standalone privilege escalation primitive.

3. Reachability analysis

The attacker needs local access to the affected qla2xxx BSG device node or equivalent SCSI BSG permissions. The supplied context supports PR:L rather than host-admin-equivalent privilege, because the attack is performed through a local device interface and does not require kernel privileges once that interface is accessible.

HostAdminRequired is set to NO because the supplied prior triage explicitly states that kernel privileges are not required and local BSG access is sufficient. NamespaceScopedPrivilege is NO because the issue is tied to SCSI BSG device access, not to an attacker-created namespace capability.

There is no network trigger. There is a hardware and driver exposure prerequisite: the affected qla2xxx driver and exposed BSG interface must exist on the system. This limits deployment exposure, but it is not a reason to treat the primitive as harmless once the interface is reachable.

No race or special timing is required. The trigger is a short request payload followed by reply copying in affected read handlers.

4. Primitive and severity interpretation

The exact primitive is an uninitialized kernel stack memory disclosure to userspace. It is not memory corruption, not UAF, not RCU lifetime misuse, and not a repeated release/refcount bug.

The affected storage is a fixed 256 byte on-stack buffer, but the disclosure path is meaningful because stale stack bytes are returned to the caller. The confirmed leak paths are qla2x00_read_fru_status() and qla2x00_read_i2c(). The write/update paths are relevant for robustness because they may send uninitialized fields onward to the device, but they do not establish a concrete integrity or availability consequence from the supplied evidence.

PrimitiveClass is CLASS_A because a direct kernel stack disclosure to userspace is an established security primitive, and repeated disclosure can be useful for defeating kernel hardening. This is not enough by itself to call the issue a strong Important candidate, but it is enough to prevent automatic downgrade.

ImportantCandidate is YES because the issue is an established kernel information disclosure primitive with possible mitigation-bypass value. AutoDowngradeAllowed is NO because automatically closing a kernel stack disclosure could miss practical exploit-assist impact.

Likely operational severity is Actionable Moderate. It should be reviewed manually, especially for device-node permissions and whether unprivileged or semi-privileged users can access the affected BSG interface in the target product.

5. One-sentence report phrase

A local qla2xxx BSG user can send short requests that leave part of a 256 byte stack buffer uninitialized, and selected read handlers then copy the full structure back to userspace, causing kernel stack information disclosure.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a concrete kernel stack information disclosure to userspace, and practical severity depends on BSG device permissions, qla2xxx hardware exposure, repeatability, and whether leaked stack bytes include kernel pointers or other sensitive values.

7. Call-site confidence

Call-site confidence: high

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

Patch: scsi: qla2xxx: Zero-init bsg stack buffers to avoid info leak
Commit: 1c820d0900e4aacd5020b989159f6b4b2f7d0d6a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1c820d0900e4aacd5020b989159f6b4b2f7d0d6a

Commit description:

Several bsg handlers stage their request/reply in an uninitialized 256-byte
on-stack buffer (uint8_t bsg[DMA_POOL_SIZE]) and fill it via
sg_copy_to_buffer(), which only copies as many bytes as the user-supplied
request payload. When the request is shorter than the structure, the
remainder of the buffer is left holding stale stack data.

qla2x00_read_fru_status() and qla2x00_read_i2c() then copy the full
structure back to the reply payload with sg_copy_from_buffer(), leaking the
uninitialized stack bytes to user space. The write/update paths do not copy
the buffer back, but can feed uninitialized fields to the device.

Zero the stack buffer at declaration in all five handlers, mirroring the
heap kzalloc() approach, so short requests can no longer expose stale
memory.

Fixes: 697a4bc ("[SCSI] qla2xxx: Provide method for updating I2C attached VPD.")
Fixes: 9ebb5d9 ("[SCSI] qla2xxx: Add I2C BSG interface.")
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/20260730155838.2119230-30-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_bsg.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=1c820d0900e4aacd5020b989159f6b4b2f7d0d6a

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

The original Linux kernel CVE announcement for CVE-2026-89843 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89843

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:L/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
  The Best / paranoid CVSS score: 6.6

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: 4
  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).