[CVE-2026-97588][LOW] s390/crypto: Map EBUSY to EIO when key conversion fails repeatedly

[CVE-2026-97588][LOW] s390/crypto: Map EBUSY to EIO when key conversion fails repeatedly

[AL-KERNEL]

CVE: CVE-2026-97588
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: s390/crypto: Map EBUSY to EIO when key conversion fails repeatedly
Commit: f6b263679aa72ad2e534bf93db55f2589549a40e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6b263679aa72ad2e534bf93db55f2589549a40e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97588
Analysis date: Sat, 26 Sep 2026 08:43:01 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97588 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97588

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-2026-97588	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97588 CHECK WITH IMPACT FROM ORIG NN LOW	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-755;CWE-703;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'Persistent EBUSY from protected key conversion can be passed to the Crypto API after all retries are exhausted. The completion wrapper interprets EBUSY as a queueing status and does not invoke the completion callback, causing callers waiting through crypto_wait_req to block indefinitely. For the CVSS the PR:L value is used because a local user or service process must submit work that reaches the affected s390 protected key crypto path. AC:H reflects the additional requirement that the hardware must continue returning EBUSY after the retry limit. The issue is not directly network reachable, although a network service using the affected crypto implementation could expose it indirectly. The realistic impact is a blocked caller or degraded crypto service. Sustained accumulation of blocked requests may cause a broader availability impact, but there is no memory corruption primitive or plausible confidentiality, integrity, or privilege escalation impact.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-97588 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	SIMPLEFIX HARDWARE LINUS 	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Availability impact realistic. Persistent `-EBUSY` is misinterpreted as a queueing status, suppressing the completion callback and leaving a caller in `crypto_wait_req()` blocked indefinitely.
* No additional availability point. Host-wide failure, persistent resource exhaustion, kernel panic, or a distinct second availability consequence is not established.
* No corruption points. The patch establishes an error-code semantic mismatch, not UAF, OOB access, invalid free, refcount corruption, or arbitrary write.
* No confidentiality or integrity points. No disclosure or unauthorized modification primitive exists.
* No remote-reachability point. A network service could expose the operation indirectly, but direct attacker-controlled network reachability is not established.
* No local-unprivileged point. The supplied evidence does not prove that an ordinary user can submit requests through the affected protected-key algorithms.
* No hardware penalty was applied. s390 protected-key hardware is a concrete prerequisite, but the issue is being evaluated on systems where the affected driver is deployed rather than penalized merely for architectural specialization.
* No timing penalty. This is an ordered error-handling failure requiring persistent hardware `-EBUSY`, not a race.

3. Reachability analysis

A local kernel caller or userspace-backed service must submit cryptographic work through the affected s390 protected-key AES or PHMAC path. The hardware must continue returning `-EBUSY` until retry exhaustion. Whether an ordinary local user can reach the complete affected path is not established, but host-admin-equivalent privilege is also not proven, so `HostAdminRequired=UNKNOWN`.

No namespace capability or namespace-scoped trigger chain is shown. Prior availability and configuration of compatible s390 protected-key hardware are required. There is no race or narrow timing window. Direct network triggering is not established, although a network-facing service using this crypto path could potentially convert the defect into a service-level hang.

4. Primitive and severity interpretation

The exact defect is incorrect propagation of a queue-status error after retries have already been exhausted. Returning `-EBUSY` causes the Crypto API completion wrapper to suppress callback execution, leaving synchronous waiters blocked.

This is `CLASS_C` availability behavior. It is not a lifetime violation and involves neither active structured stale objects nor fixed stale storage. There is no repeated release or refcount mutation. The demonstrated consequence is an indefinitely blocked caller or degraded crypto service. Broader host-wide exhaustion would require additional evidence of repeatable request accumulation and is not scored.

`ImportantCandidate=NO` because no corruption, authorization bypass, ownership violation, disclosure, or privilege-escalation primitive exists. `AutoDowngradeAllowed=YES` because the established effect is constrained availability loss without unresolved exploitation leverage.

5. One-sentence report phrase

Persistent EBUSY after protected-key conversion retry exhaustion can suppress Crypto API completion callbacks and block callers indefinitely, causing a local service-level denial of service without evidence of memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a narrow error-propagation defect with availability-only consequences and no unresolved memory-safety or security-boundary primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: s390/crypto: Map EBUSY to EIO when key conversion fails repeatedly
Commit: f6b263679aa72ad2e534bf93db55f2589549a40e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6b263679aa72ad2e534bf93db55f2589549a40e

Commit description:

When hardware persistently returns -EBUSY after exhausting retries,
the error propagates to crypto_finalize_*_request(). The crypto API's
completion wrapper treats -EBUSY as a queueing status and swallows it,
preventing the completion callback from firing. This causes callers
using crypto_wait_req() to block indefinitely.

Translate persistent -EBUSY to -EIO after retry exhaustion to ensure
proper error propagation and callback invocation.

Fixes: 6cd87cb ("s390/crypto: Rework protected key AES for true asynch support")
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Cc: stable@vger.kernel.org # 6.16+
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  arch/s390/crypto/paes_s390.c
  arch/s390/crypto/phmac_s390.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=f6b263679aa72ad2e534bf93db55f2589549a40e

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

The original Linux kernel CVE announcement for CVE-2026-97588 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97588

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: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: unknown
  Paranoid ActionableScore: 1

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).