[CVE-2026-64005][MODERATE 7.0] net/smc: Do not re-initialize smc hashtables [ Upstream

[CVE-2026-64005][MODERATE 7.0] net/smc: Do not re-initialize smc hashtables [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64005
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net/smc: Do not re-initialize smc hashtables [ Upstream
Commit: cdc79c05cc375f68ae87b0c74fdaac1a5c93155a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cdc79c05cc375f68ae87b0c74fdaac1a5c93155a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64005
Analysis date: Sun, 19 Jul 2026 16:20:30 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A local race during SMC initialization can reset global socket hash list heads after entries may already exist, causing corrupted hlist state and possible kernel DoS, with broader memory-lifetime impact requiring manual review.

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

The original Linux kernel CVE announcement for CVE-2026-64005 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64005

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-2026-64005	MODERATE	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:H/I:H/A:H';CWE-362;CWE-665;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'SMC hash list heads could be re initialized after the protocol and socket family were already registered. If an SMC socket is created during this initialization window, an existing hash entry may be lost or the hlist state may become corrupted. For the CVSS the PR:L is used for the paranoid score because a local unprivileged process may be able to create AF_SMC sockets or race module autoload, while full administrative control is not necessarily required for the socket operation itself. The issue is not directly network reachable and depends on local timing during SMC initialization. Impact is at least local denial of service via corrupted socket hash state and kernel crash. In the worst still defensible interpretation, hlist corruption in struct sock lifetime management may allow broader confidentiality or integrity impact and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	INIT SIMPLEFIX LINUS  INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. AF_SMC socket creation is plausibly reachable by a local user once the socket family is registered.
* Memory corruption, weak/indirect corruption candidate: +1. The patch explicitly prevents resetting an hlist head while entries may already exist, which can corrupt socket hash list state.
* Real lifetime corruption: +1. The affected objects are socket hash entries tied to struct sock lifetime and lookup/unhash behavior.
* Availability impact realistic: +1. Corrupted global SMC hash state can plausibly lead to crashes, hangs, or broken SMC socket handling.
* Hard or unreliable race / special timing required: -1. The vulnerable window is during SMC initialization after registration but before the removed reinitialization point.

Paranoid additional signals:

* Weak LPE concern: +1. Kernel hlist corruption in socket lifetime management is a plausible manual-review concern, although no reclaim, callback control, arbitrary write, or demonstrated privilege escalation primitive is shown.
* Reliable kernel crash / strong DoS: +1. In the paranoid interpretation, corrupting a global protocol hash list can produce a strong kernel DoS or persistent corrupted subsystem state.

Not applied:

* Remote reachable: +0. The issue is not packet-triggered and requires local timing around SMC initialization.
* Strong memory corruption primitive: +0. The patch does not show attacker-controlled overwrite, UAF reclaim, type confusion, arbitrary write, or callback control.
* Common networking packet path: +0. This is SMC socket initialization/hash management, not a central packet receive path.

## 3. Reachability analysis

A local process may be able to trigger the issue by creating AF_SMC sockets during the narrow window after proto_register() and sock_register() expose the protocol but before smc_init() previously reinitialized the hash heads. If SMC is built into the kernel and initialized before untrusted userspace starts, practical reachability is much lower. If SMC is modular or autoloaded, a local user may have a more plausible race opportunity.

Namespaces may matter if AF_SMC socket creation is available inside a container or delegated network namespace, but the attacker still needs local code execution. The path is not directly network reachable. Realistic exploitation depends on CONFIG_SMC, module or init timing, and whether unprivileged users can create SMC sockets in the target environment.

Call-site confidence: medium. The patch shows the dangerous reinitialization point and global hash objects, but not a concrete crash trace or later corrupted-list traversal.

## 4. Severity interpretation

This is more than an ordinary correctness fix because it can corrupt a global kernel hlist after socket entries may already exist. The realistic conservative impact is local DoS or broken SMC socket state under a hard timing window. The theoretical concern is broader memory/lifetime corruption in struct sock hash management, but the patch does not demonstrate a strong exploit primitive such as controlled reclaim, arbitrary write, callback dispatch, or type confusion.

Therefore this is best treated as borderline to actionable Moderate, with manual review justified. It is not a strong Important candidate on the conservative evidence alone.

## 5. One-sentence report phrase

A local race during SMC initialization can reset global socket hash list heads after entries may already exist, causing corrupted hlist state and possible kernel DoS, with broader memory-lifetime impact requiring manual review.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch explicitly prevents corrupted kernel list state in socket lifetime management. The reachable window is narrow, but list corruption in struct sock hash handling is security-relevant enough that it should not be auto-closed without manual inspection of initialization timing and AF_SMC socket creation reachability.

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

Patch: net/smc: Do not re-initialize smc hashtables [ Upstream
Commit: cdc79c05cc375f68ae87b0c74fdaac1a5c93155a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cdc79c05cc375f68ae87b0c74fdaac1a5c93155a

Changed files:
  net/smc/af_smc.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=cdc79c05cc375f68ae87b0c74fdaac1a5c93155a

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

The original Linux kernel CVE announcement for CVE-2026-64005 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64005

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:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 3
  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: NO
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).