[CVE-2026-90202][LOW] scsi: mpt3sas: Avoid freeing unallocated PCIe SGL buffers [ Upstream

[CVE-2026-90202][LOW] scsi: mpt3sas: Avoid freeing unallocated PCIe SGL buffers [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90202
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: scsi: mpt3sas: Avoid freeing unallocated PCIe SGL buffers [ Upstream
Commit: 3361709fb6f6568b157c6f24ed21a4a5d86d73db
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3361709fb6f6568b157c6f24ed21a4a5d86d73db
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90202
Analysis date: Fri, 18 Sep 2026 01:27:23 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-90202 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90202

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-90202	LOW	https://www.kernelcve.org/list/?q=CVE-2026-90202 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:H/UI:N/S:U/C:N/I:N/A:H';CWE-763;**CWE-476;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.4';DESCR 'The mpt3sas cleanup path can call dma_pool_free() for PCIe SGL entries that were never allocated after a partial setup failure. On debug kernels this may produce a bad dma warning, and on other kernels it can result in a NULL pointer dereference and a local kernel crash (DoS). For the CVSS the PR:H is used because reliable triggering normally requires administrative control over driver probing, module load or device reset paths, plus a partial allocation failure during setup. The issue is not network reachable. Impact is denial of service only, with no supported evidence of information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	NULLPTR SIMPLEFIX HARDWARE LINUS MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score.

2. Signal breakdown

Positive signals:

* +1 Class C invalid cleanup operation. `_base_release_memory_pools()` can call `dma_pool_free()` on PCIe SGL entries that were never allocated after partial setup failure.
* +1 Reliable kernel crash / strong DoS. The supplied commit text states this can cause a bad DMA warning on debug kernels or a NULL pointer dereference otherwise.

Negative signals:

* -2 Host-admin-equivalent trigger requirement. Reliable attacker triggering appears to require administrative control over driver probing, module load, device reset, or comparable host device-management paths, plus a partial setup failure.

Non-awarded signals:

* Real UAF not awarded. The patch shows freeing an unallocated or NULL PCIe SGL buffer entry, not post-lifetime use of an object that was previously freed.
* Concrete repeated release/refcount not awarded. There is no established first release that can end lifetime, no surviving exact dangling reference, and no later second lifetime/refcount mutation on that same reference.
* Controlled reclaim not demonstrated.
* Arbitrary or directed kernel write not demonstrated.
* Confidentiality and integrity impact not awarded.
* Remote reachability not established.
* Extra Availability not awarded because the same NULL dereference crash is already counted once.
* ImportantCandidate not set because the demonstrated primitive is crash-oriented and lacks unresolved exploitation leverage beyond DoS.

Repeated-release checklist:

* First release can end lifetime: NO.
* Exact same reference survives: NO.
* Second operation is a real lifetime/refcount mutation: NO.
* +1 Concrete repeated release/refcount awarded: NO.
* Paranoid repeated-refcount leverage +1 awarded: NO.
* FLOOR 5 applied: NO.

3. Reachability analysis

The affected path is in the `mpt3sas` SCSI driver cleanup path during release of memory pools. The triggering condition is a partial failure in PCIe SGL buffer setup followed by cleanup. The supplied evidence does not show that an ordinary local user can reliably cause this sequence.

Reliable exploitation appears to require host-level device management such as probing, loading, unloading, resetting, or otherwise forcing the driver through the failing initialization and cleanup path. That is host-admin-equivalent in practical security terms.

No namespace-scoped capability path is established. This is a physical or host-owned storage controller driver path, not a network namespace or attacker-created virtual object path. No direct remote trigger is established. No special rare-hardware penalty is separately applied because the host-admin requirement already captures the main reachability reduction and because the driver-specific nature alone should not be double-counted.

There is no race requirement shown. The issue is an ordered error/cleanup path after partial allocation failure.

4. Primitive and severity interpretation

The exact primitive is an invalid cleanup/free attempt on PCIe SGL entries that were never allocated. The demonstrated result is a bad DMA warning on debug kernels or a NULL pointer dereference on other kernels.

This is not an active structured-object UAF. It is not a fixed async stale-buffer UAF either. It is best classified as Class C invalid-state cleanup behavior with crash impact.

There is no concrete repeated lifetime/refcount mutation. The vulnerable operation is not a second `put`, `release`, `free`, or refcount decrement after an earlier operation may have destroyed the same object. It is a cleanup loop that fails to skip unallocated entries.

PrimitiveClass is CLASS_C. Demonstrated consequence is local DoS through kernel warning or crash. Speculative consequence beyond DoS is not supported by the supplied patch or commit text. There is no evidence of privilege escalation, information disclosure, controlled corruption, callback influence, DMA overwrite of attacker-selected memory, or security-boundary bypass.

ImportantCandidate=NO because the issue is host-admin-gated and crash-only with no meaningful unresolved exploitation primitive. AutoDowngradeAllowed=YES because automatic downgrade would not discard an established Class A or strong Class B primitive.

Likely operational severity is ordinary Moderate or Low-like for security triage, despite a possible kernel crash, because a host-admin-equivalent actor is required for reliable triggering.

5. One-sentence report phrase

The mpt3sas cleanup path may call dma_pool_free() for PCIe SGL entries that were never allocated after partial setup failure, causing a bad DMA warning or NULL pointer dereference, but reliable triggering appears to require host administrative control over driver setup or reset paths and the impact is DoS only.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a constrained host-admin-gated cleanup crash without UAF, repeated lifetime mutation, controlled corruption, remote reachability, or security-boundary bypass.

7. Call-site confidence

Call-site confidence: medium

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

Patch: scsi: mpt3sas: Avoid freeing unallocated PCIe SGL buffers [ Upstream
Commit: 3361709fb6f6568b157c6f24ed21a4a5d86d73db
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3361709fb6f6568b157c6f24ed21a4a5d86d73db

Changed files:
  drivers/scsi/mpt3sas/mpt3sas_base.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=3361709fb6f6568b157c6f24ed21a4a5d86d73db

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

The original Linux kernel CVE announcement for CVE-2026-90202 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90202

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.4

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: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).