[CVE-2026-45898][IMPORTANT] RDMA/iwcm: Fix workqueue list corruption by removing work_list [ Upstream

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

CVE: CVE-2026-45898
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: RDMA/iwcm: Fix workqueue list corruption by removing work_list [ Upstream
Commit: 38c5b49fffa1b760959af74f11806eeb3ef4706d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=38c5b49fffa1b760959af74f11806eeb3ef4706d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45898
Analysis date: Wed, 27 May 2026 22:31:48 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
An RDMA iwcm workqueue lifetime bug can reuse an `iwcm_work` object while its embedded `work_struct` is still queued, causing workqueue list corruption and kernel crash, with possible RDMA fabric reachability in exposed iWARP environments.

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

The original Linux kernel CVE announcement for CVE-2026-45898 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45898

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: IMPORTANT
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-2026-45898	IMPORTANT	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:H/I:H/A:H';CWE-362;*CWE-416;*CWE-664;*CWE-787;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'An RDMA iwcm workqueue lifetime bug can reuse an iwcm_work object from the free list while its embedded work_struct is still queued. This can corrupt internal workqueue lists and trigger a kernel BUG during RDMA CM event processing. For the CVSS the PR:N is used in the paranoid score only for deployments where a remote RDMA or iWARP peer can generate the relevant CM events on the RDMA fabric. The conservative case is PR:L because local RDMA device access can drive the stressed event path. The issue is not ordinary Internet remote by default, but it may be fabric reachable in exposed RDMA environments. Impact is at least denial of service through kernel crash. Because this is real workqueue list corruption, worst case confidentiality and integrity impact cannot be ruled out without manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) 	MAYBE	LOCK DANGER INIT NETWORK KERNEL_PANIC_PLUS_UAF HARDWARE LINUS TEST KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

* Local trigger with RDMA access: +1
  A local user or service with access to RDMA/iWARP resources can drive RDMA CM event activity.

* Generic memory corruption: +2
  The issue causes real workqueue list corruption involving reused `iwcm_work` objects with embedded `work_struct`.

* Real lifetime corruption: +1
  An `iwcm_work` object can be returned to the free list and reused while its embedded work item is still queued.

* Reliable kernel crash / strong DoS: +1
  The report shows `list_del corruption` followed by a kernel BUG in workqueue/list handling.

* Availability impact realistic: +1
  The practical demonstrated impact is kernel crash under RDMA CM stress.

* Fabric / adjacent reachability in paranoid scoring: +2
  In exposed RDMA or iWARP deployments, a remote peer on the RDMA fabric may be able to generate relevant CM events. This is not ordinary Internet remote reachability.

* Hard or stress-dependent triggering: -1
  The observed issue was reproduced under stress testing with `ucmatose`, so reliable exploitation may require event pressure and timing.

* No proven arbitrary write or LPE primitive: +0
  The patch demonstrates list corruption and object lifetime misuse, but not a controlled overwrite or privilege escalation chain.

## 3. Reachability analysis

Conservatively, triggering requires local access to an RDMA/iWARP device or test tool that can generate RDMA CM events. In multi-tenant RDMA environments, device access may be delegated to non-root workloads.

Paranoid interpretation treats this as adjacent/fabric reachable if a remote RDMA/iWARP peer can generate enough CM event churn against an exposed service. It is not a generic TCP/IP remote bug and should not be scored as Internet-reachable by default.

## 4. Severity interpretation

This is more serious than ordinary Moderate because it is real kernel list corruption involving `work_struct` lifetime and reuse. The demonstrated impact is DoS via kernel BUG, but memory corruption class means confidentiality or integrity impact cannot be fully dismissed without manual analysis. It is an Important candidate in RDMA-exposed deployments.

## 5. One-sentence report phrase

An RDMA iwcm workqueue lifetime bug can reuse an `iwcm_work` object while its embedded `work_struct` is still queued, causing workqueue list corruption and kernel crash, with possible RDMA fabric reachability in exposed iWARP environments.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

This is real workqueue/list corruption and a lifetime bug, not a simple WARN or resource leak. Manual review is needed to determine whether the corruption is controllable beyond DoS and whether remote RDMA peers can trigger it in affected deployments.

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

Patch: RDMA/iwcm: Fix workqueue list corruption by removing work_list [ Upstream
Commit: 38c5b49fffa1b760959af74f11806eeb3ef4706d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=38c5b49fffa1b760959af74f11806eeb3ef4706d

Changed files:
  lib/list_debug.c
  drivers/infiniband/core/iwcm.c
  drivers/infiniband/core/iwcm.h

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=38c5b49fffa1b760959af74f11806eeb3ef4706d

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

The original Linux kernel CVE announcement for CVE-2026-45898 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45898

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:L/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: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: 5
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).