[CVE-2026-46068][LOW] crypto: nx - fix bounce buffer leaks in nx842_crypto_{alloc,free}_ctx [ Upstream

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

CVE: CVE-2026-46068
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: crypto: nx - fix bounce buffer leaks in nx842_crypto_{alloc,free}_ctx [ Upstream
Commit: f17a4850d1ce7c11cba8b1830b9bfedfede878bb
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f17a4850d1ce7c11cba8b1830b9bfedfede878bb
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46068
Analysis date: Wed, 27 May 2026 10:15:33 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
NX 842 bounce buffers allocated as order 2 page blocks were freed as single pages, causing a hardware-dependent local resource leak that may lead to memory-pressure DoS only if context creation can be repeated.

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

The original Linux kernel CVE announcement for CVE-2026-46068 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46068

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.

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

CVE-2026-46068	LOW	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-404;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'NX 842 bounce buffers are allocated as order 2 page blocks but were released with free_page(), so only one page from each buffer was returned and the remaining pages could leak. Repeated context allocation and free cycles may cause memory pressure or denial of service on systems using the NX 842 crypto driver. For the CVSS the PR:L is used in the paranoid score only if a less privileged local user can repeatedly instantiate this crypto context through an exposed local consumer. The typical case is more restricted and hardware dependent because NX 842 requires the matching platform support. The issue is not network reachable and does not provide UAF, out of bounds write, arbitrary write, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	SIMPLEFIX LEAK ERRORPATH HARDWARE LINUS 	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Conservative signals:

* Availability impact weakly plausible: +1
  Repeated allocation and free cycles could leak pages and eventually contribute to memory pressure.

* Requires admin/root or privileged kernel consumer in typical deployments: -2
  The affected NX 842 context allocation is normally reached through hardware crypto users or system configuration, not a broadly exposed unprivileged interface.

* Rare hardware/configuration-dependent path: -1
  NX 842 requires matching platform hardware and driver support.

Paranoid signals:

* Availability impact realistic under repeated abuse: +1
  If an attacker can repeatedly instantiate the affected crypto context, the order 2 bounce buffer leak can accumulate.

* Local lower-privilege trigger concern: +1
  Counted only for environments where a less privileged local user can indirectly create and destroy NX 842 crypto contexts through an exposed local consumer.

No signals apply for remote reachability, UAF, OOB write, double free, arbitrary write, page-cache corruption, privilege escalation, sensitive-object access, or security-boundary bypass.

## 3. Reachability analysis

The bug is triggered when NX 842 bounce buffers allocated with `__get_free_pages(..., BOUNCE_BUFFER_ORDER)` are released with `free_page()` instead of `free_pages()` with the matching order. In typical deployments, this path requires NX 842 hardware support and a kernel or privileged system component that instantiates the compression context.

Namespaces and containers do not generally make this reachable unless the environment exposes a crypto consumer that allows repeated context creation by less trusted users. The issue is not network reachable.

## 4. Severity interpretation

This behaves like a Low-like resource leak, not an actionable Moderate or Important issue. The patch fixes mismatched page allocation and free order, which can leak memory, but it does not show memory corruption, UAF, OOB access, information disclosure, or privilege escalation.

The realistic impact is resource exhaustion only under repeated triggering on affected hardware. The paranoid score remains low because even the higher-risk interpretation is still DoS-only.

## 5. One-sentence report phrase

NX 842 bounce buffers allocated as order 2 page blocks were freed as single pages, causing a hardware-dependent local resource leak that may lead to memory-pressure DoS only if context creation can be repeated.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a hardware-dependent resource leak with no memory corruption primitive, no remote exposure, and no supported privilege-escalation path.

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

Patch: crypto: nx - fix bounce buffer leaks in nx842_crypto_{alloc,free}_ctx [ Upstream
Commit: f17a4850d1ce7c11cba8b1830b9bfedfede878bb
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f17a4850d1ce7c11cba8b1830b9bfedfede878bb

Changed files:
  drivers/crypto/nx/nx-842.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=f17a4850d1ce7c11cba8b1830b9bfedfede878bb

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

The original Linux kernel CVE announcement for CVE-2026-46068 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46068

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 2

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).