[CVE-2026-98871][LOW] crypto: ccp - Fix possible deadlock in SEV init failure path [ Upstream

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

CVE: CVE-2026-98871
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: crypto: ccp - Fix possible deadlock in SEV init failure path [ Upstream
Commit: 8e7e06ee7c2938ee3fa31a61cc5289a45c8c13f1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8e7e06ee7c2938ee3fa31a61cc5289a45c8c13f1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98871
Analysis date: Mon, 26 Oct 2026 14:30:28 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A host-administrator SEV INIT_EX operation can deadlock the SEV command path after a partially successful RMPUPDATE failure because cleanup attempts to reacquire an already-held mutex.

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

The original Linux kernel CVE announcement for CVE-2026-98871 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98871

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-2026-98871	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98871 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';*CWE-833;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'An incorrect lock state is passed while converting the SEV INIT_EX nonvolatile buffer to firmware pages. If RMPUPDATE fails after at least one page was converted, cleanup can reenter sev_do_cmd and attempt to acquire the already held sev_cmd_mutex, causing a deadlock in the SEV command path. For the CVSS the PR:H value is selected because reaching SEV platform INIT_EX normally requires privileged host administration, and AC:H reflects the required partial RMPUPDATE failure that is not shown to be attacker controlled. The demonstrated impact is availability loss for SEV initialization or later SEV commands. There is no supported memory corruption, confidentiality loss, integrity loss, guest to host escape, or direct network trigger. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 4.1 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to LOW because the CVSS score, vector or bug class threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH. The independent weaker Aegis shadow evaluated CVSS 1.9 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	DEADLOCK INIT SIMPLEFIX  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: -2.
* Conservative score: 0 after lower-bound normalization.
* Raw paranoid score: -2.
* Paranoid score: 0 after lower-bound normalization.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable strong DoS: after a partial RMPUPDATE failure, cleanup reenters `sev_do_cmd()` and attempts to reacquire the already-held `sev_cmd_mutex`, deadlocking the SEV command path.
* -2 Proven host-administrator requirement: SEV platform `INIT_EX` is a host-global privileged administration operation.
* -1 Difficult failure prerequisite: triggering requires RMPUPDATE to succeed for at least one page and then fail; attacker control or reliable induction of that partial failure is not shown.
* No memory corruption, UAF, OOB access, authorization bypass, confidentiality impact, integrity impact, or guest-to-host primitive is shown.
* No additional availability point: SEV command-path deadlock is the sole demonstrated effect.
* NEW52/B5-R and NEW53/B3-PENDING do not apply: there is no write primitive. B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW.

3. Reachability analysis

The complete path is host platform initialization performed with effective host-administrator authority. Numeric UID 0 is not established as mandatory, hence `RequiresHostUID0=UNKNOWN`; however, this is not a namespace-scoped or guest-triggerable operation. No normal-user, delegated capability, malicious-guest, or remote trigger is supported. The necessary partial RMPUPDATE failure is hardware/firmware-state dependent and not shown attacker-controllable.

4. Primitive and severity reading

The defect is incorrect lock-state propagation: `locked=false` causes cleanup to reacquire a mutex already held by the parent initialization path. The one-line fix passes `locked=true`, avoiding recursive acquisition. This is a synchronization deadlock rather than memory or active-state corruption, so `PrimitiveClass=NONE`. The shown consequence is loss of SEV initialization or command availability; host panic, host-wide DoS, data corruption, isolation bypass, and privilege escalation are unproven. Host-admin gating and the unusual partial-failure condition make Important review unwarranted.

5. One-sentence report phrase

A host-administrator SEV INIT_EX operation can deadlock the SEV command path after a partially successful RMPUPDATE failure because cleanup attempts to reacquire an already-held mutex.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch establishes a privileged, condition-dependent deadlock with no corruption or unresolved security-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: crypto: ccp - Fix possible deadlock in SEV init failure path [ Upstream
Commit: 8e7e06ee7c2938ee3fa31a61cc5289a45c8c13f1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8e7e06ee7c2938ee3fa31a61cc5289a45c8c13f1

Changed files:
  drivers/crypto/ccp/sev-dev.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=8e7e06ee7c2938ee3fa31a61cc5289a45c8c13f1

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

The original Linux kernel CVE announcement for CVE-2026-98871 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98871

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:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.1

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: 0

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).