[CVE-2026-45857][MODERATE REGULAR] scsi: csiostor: Fix dereference of null pointer rn [ Upstream

[CVE-2026-45857][MODERATE REGULAR] scsi: csiostor: Fix dereference of null pointer rn [ Upstream

[AL-KERNEL]

CVE: CVE-2026-45857
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: scsi: csiostor: Fix dereference of null pointer rn [ Upstream
Commit: 16ccbfddcb32365138c806cf572e69b42a193c5c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=16ccbfddcb32365138c806cf572e69b42a193c5c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45857
Analysis date: Wed, 27 May 2026 09:09:09 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-45857 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45857

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 REGULAR
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-2026-45857	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-703;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.3';DESCR 'A NULL pointer dereference exists in the csiostor SCSI LUN reset error path because rn can be NULL and the common fail label still calls CSIO_INC_STATS on rn. This can crash the kernel during SCSI error recovery when the driver cannot resolve the remote node for the command. For the CVSS the PR:N is used only for the paranoid adjacent network case where a storage fabric peer or target side condition can influence SCSI error recovery without local privileges on the victim. In the more realistic base case triggering requires local administrative storage or device management control. The issue is not Internet reachable and is limited to systems using the Chelsio csiostor FCoE driver. Impact is denial of service only via kernel crash, with no evidence of information disclosure, privilege escalation, UAF, or arbitrary write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 2)	YES	SIMPLEFIX HARDWARE  INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	NO	NO	checked

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

ActionableScore=3
ActionableScoreLower=1

1. ActionableScore
* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended**::

2. Signal breakdown
* Reliable kernel crash / strong DoS: +1. The NULL `rn` pointer can be dereferenced through `CSIO_INC_STATS()`, causing a kernel crash in the SCSI error recovery path.
* Important filesystem/storage path: +1. The bug is in a SCSI/FCoE storage driver LUN reset handler.
* Availability impact realistic: +1. A reachable NULL dereference in error handling can disrupt the host using the affected adapter.
* Firmware-mediated or fabric-mediated external influence: +1 in paranoid scoring. A storage fabric peer, target-side error condition, or FCoE environment may influence SCSI error recovery, but this is not general Internet/network reachability.
* Rare and difficult-to-reach subsystem/configuration: -1. The issue is limited to the Chelsio `csiostor` FCoE offload driver and requires affected hardware/configuration.
* Requires admin/device-management control in the conservative case: -2. Local reliable triggering usually requires privileged storage/device management or fault injection.
* Weak corruption only: +0. This is a NULL pointer dereference, not UAF, OOB write, arbitrary write, or controlled memory corruption.

3. Reachability analysis
The affected path is `csio_eh_lun_reset_handler()` during SCSI LUN reset/error recovery. A local administrator or storage management component can likely trigger the path more reliably. In a paranoid storage-fabric interpretation, a target-side or fabric-induced error condition may cause the host to enter this recovery path without local privileges on the victim, but this depends on Chelsio FCoE deployment and specific error conditions. Containers and user namespaces generally do not help unless they are delegated direct storage/device control. The bug is not Internet reachable and not triggered by ordinary local users.

4. Severity interpretation
This behaves like a low to borderline Moderate DoS issue. The theoretical impact is kernel crash through NULL pointer dereference in a privileged storage driver path. There is no evidence of memory corruption beyond NULL dereference, no privilege escalation primitive, no information disclosure, and no attacker-controlled overwrite. Manual review is reasonable only because storage error recovery may be externally influenced in some SAN/FCoE deployments.

5. One-sentence report phrase
A NULL pointer dereference in the Chelsio csiostor SCSI LUN reset error path can crash the kernel when error recovery reaches `CSIO_INC_STATS()` with a missing remote node.

6. Manual review recommendation
MANUAL CHECK RECOMMENDED
The issue is DoS-only and hardware-specific, but storage fabric influence may make reachability environment-dependent, so affected deployments should be checked.

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

Patch: scsi: csiostor: Fix dereference of null pointer rn [ Upstream
Commit: 16ccbfddcb32365138c806cf572e69b42a193c5c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=16ccbfddcb32365138c806cf572e69b42a193c5c

Changed files:
  drivers/scsi/csiostor/csio_scsi.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=16ccbfddcb32365138c806cf572e69b42a193c5c

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

The original Linux kernel CVE announcement for CVE-2026-45857 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45857

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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.3

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: 1
  Paranoid ActionableScore: 3

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 REGULAR

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).