[CVE-2026-80652][LOW] crypto: ccp - Treat zero-length cert chain as query for blob lengths [ Upstream

[CVE-2026-80652][LOW] crypto: ccp - Treat zero-length cert chain as query for blob lengths [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80652
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: crypto: ccp - Treat zero-length cert chain as query for blob lengths [ Upstream
Commit: 1c587f30c6242cc37b3d6ee6d91daef84e51633f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1c587f30c6242cc37b3d6ee6d91daef84e51633f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80652
Analysis date: Fri, 28 Aug 2026 04:03:13 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A local input validation flaw in the crypto ccp SEV PDH export ioctl can treat a zero length certificate chain buffer as an allocation and trigger a CONFIG_DEBUG_VIRTUAL dependent kernel BUG, causing local denial of service only for users or services with access to the SEV device.

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

The original Linux kernel CVE announcement for CVE-2026-80652 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80652

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.

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

CVE-2026-80652	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-20;CWE-617;**CWE-476;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A local ioctl input validation bug in crypto ccp SEV PDH export can treat a zero length cert chain buffer as a real allocation instead of a length query. With CONFIG_DEBUG_VIRTUAL enabled, kzalloc(0) returns ZERO_SIZE_PTR and the driver later attempts to translate it to a physical address, which can hit a kernel BUG in __phys_addr and cause an Oops or panic. For the CVSS the PR:L is used in the paranoid score because access may be available to a virtualization service account or a reduced capability root context that can issue SEV ioctls. The issue is not network reachable and requires local access to the SEV device or the process that controls it. Impact is denial of service only in the affected debug configuration, with no supported path to information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	KASAN OOB KERNEL_PANIC_PLUS_UAF HARDWARE DEBUGFS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Triggered signals:

* Reliable kernel crash / strong DoS: +1
  The patch describes a concrete BUG in `__phys_addr()` caused by translating `ZERO_SIZE_PTR` after `kzalloc(0)`, but only with `CONFIG_DEBUG_VIRTUAL=y`.

Subtracted / limiting signals:

* Requires admin/root or privileged device access in typical deployments: -2
  The affected path is `SEV_PDH_CERT_EXPORT` through the CCP SEV ioctl path. Access is normally limited to root or privileged virtualization management processes.

* Legacy / non-default execution mode: -1
  The demonstrated crash depends on `CONFIG_DEBUG_VIRTUAL=y`, which is a debug-oriented kernel configuration and not typical for production kernels.

* Rare AND difficult-to-reach subsystem/configuration: -1
  The issue requires AMD SEV/CCP device availability and access to the SEV ioctl interface.

Not awarded:

* No local unprivileged trigger in the typical deployment.
* No remote/network reachability.
* No UAF, double-free, OOB write, refcount takeover, type confusion, or arbitrary write.
* No confidentiality or integrity impact supported by the patch.
* No privilege escalation plausibility supported.

## 3. Reachability analysis

The bug is triggered locally through the SEV ioctl path by passing a zero-length certificate-chain buffer to the PDH export operation. In normal deployments, this interface is expected to be reachable only by root, a hypervisor management stack, or a privileged virtualization service account. A paranoid interpretation can treat such a service account or reduced-capability root context as weaker than full host root, but it still does not make the issue truly unprivileged.

The path is not network reachable. It also depends on AMD SEV/CCP support and is only shown to crash with `CONFIG_DEBUG_VIRTUAL=y`. The commit explicitly states that outside this configuration the behavior is benign because the physical-address calculation is arithmetic and the PSP rejects the command before writing to the bogus address.

Call-site confidence: high. The patch and trace show the direct ioctl call path into `sev_ioctl_do_pdh_export()` and the exact failing operation.

## 4. Severity interpretation

This behaves like a low-end local DoS / validation bug, not an Important-class kernel vulnerability. The demonstrated impact is a kernel BUG/Oops under a debug configuration. There is no evidence of a practical memory corruption primitive, no attacker-controlled write target, no reclaim or lifetime issue, and no supported path to privilege escalation.

The theoretical concern is limited to bogus physical address handling, but the commit explicitly explains why this does not become a real write primitive in normal configurations.

## 5. One-sentence report phrase

A local input validation flaw in the crypto ccp SEV PDH export ioctl can treat a zero length certificate chain buffer as an allocation and trigger a CONFIG_DEBUG_VIRTUAL dependent kernel BUG, causing local denial of service only for users or services with access to the SEV device.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a narrow ioctl validation bug with a concrete debug-config crash and no supported memory corruption, privilege escalation, confidentiality, integrity, or network exposure signal.

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

Patch: crypto: ccp - Treat zero-length cert chain as query for blob lengths [ Upstream
Commit: 1c587f30c6242cc37b3d6ee6d91daef84e51633f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1c587f30c6242cc37b3d6ee6d91daef84e51633f

Changed files:
  arch/x86/mm/physaddr.c
  drivers/crypto/ccp/sev-dev.c
  fs/ioctl.c
  arch/x86/entry/syscall_64.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=1c587f30c6242cc37b3d6ee6d91daef84e51633f

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

The original Linux kernel CVE announcement for CVE-2026-80652 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80652

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:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 0
  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).