* [CVE-2026-93179][MODERATE REGULAR] drm/amd/powerplay: fix VoltageObjectInfo zero-stride loop and OOB read [ Upstream
@ 2026-09-17 20:24 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-17 20:24 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93179
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amd/powerplay: fix VoltageObjectInfo zero-stride loop and OOB read [ Upstream
Commit: 83c680de6d41d627c077dedb24f89d9e5be0e2a2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=83c680de6d41d627c077dedb24f89d9e5be0e2a2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93179
Analysis date: Thu, 17 Sep 2026 16:24:13 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93179 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93179
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 REGULAR
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-2026-93179 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93179 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:H/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-835;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.1';DESCR 'A malformed AMD GPU VBIOS VoltageObjectInfo table can cause the powerplay parser to loop forever or read past the end of the heap allocated firmware table. The bug is caused by trusting the per object size field before checking that the header is present, that the object size is at least the header size, and that the next offset stays inside the table. For the CVSS the PR:H is selected because reliable triggering normally requires administrative control over the GPU firmware image, the driver load path, or a malicious device configuration. The issue is not network reachable. Impact is primarily denial of service through an infinite loop or kernel crash. Because the primitive includes a heap out-of-bounds read from firmware supplied data, limited confidentiality impact is kept in the paranoid score and the issue should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) SKIP CVE-2026-93179 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE OOB SIMPLEFIX HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 3
* Conservative score: 3. No floor or cap applied.
* Raw paranoid score: 3
* Paranoid score: 3. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Positive signals:
* +1 Firmware-mediated external influence. The malformed input comes from the AMD GPU VBIOS VoltageObjectInfo table, so device or firmware mediation is material.
* +1 Weak corruption or invalid-read candidate. The patch directly prevents a heap OOB read from the firmware table parser, but no disclosure path or subsequent write is established.
* +1 Reliable DoS concern. A zero or undersized object size can cause a zero-stride infinite loop, and the OOB read can plausibly cause a kernel fault during driver initialization or powerplay parsing.
Negative signals:
* No host-admin penalty applied. Reliable software triggering likely requires administrative control over firmware, driver load, or device configuration, but the evidence does not prove that host-admin-equivalent privilege is the only possible attacker model because malformed device firmware or malicious hardware is also part of the input model.
* No race or timing penalty applied. This is deterministic malformed-table parsing, not a timing race.
* No rare-hardware penalty applied. AMD GPU specific code is hardware dependent, but common GPU hardware is not automatically rare or physical-only.
Important non-awarded signals:
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Real UAF not established.
* Confidentiality impact not awarded because the OOB read is internal and no read-back or disclosure path is shown.
* Integrity impact not awarded because no out-of-bounds write, state overwrite, or authorization bypass is shown.
* Extra availability point not awarded because the same infinite loop or crash is already counted as the DoS signal.
* Strong LPE or strong exploitation leverage not awarded because the patch establishes malformed firmware parsing leading to loop or OOB read, not controlled kernel corruption.
3. Reachability analysis
The vulnerable path is reached when the AMD powerplay code parses VoltageObjectInfo objects from VBIOS or atomfirmware tables. A normal remote network attacker cannot reach this path directly.
The practical trigger requires a malformed VBIOS table. In a pure software attacker model, reliable triggering likely requires administrative control over the firmware image, driver load path, test hardware, or equivalent device setup. In a device-threat model, a malicious or compromised GPU firmware image could supply the malformed table. The supplied evidence does not fully resolve which attacker role is intended, so HostAdminRequired is UNKNOWN rather than YES.
NamespaceScopedPrivilege is NO because this is not a namespace-scoped kernel interface. There is no evidence that an unprivileged user namespace, network namespace, or container capability can create the malformed VBIOS input or force the complete vulnerable operation.
No special timing is required. The bug is an input-validation failure in a parser loop.
4. Primitive and severity interpretation
The exact primitive is malformed firmware-table parsing. The old loop trusted the per-object size field before proving that a complete object header was present, that the object size was at least the header size, and that advancing by that size stayed inside the table.
This can produce two demonstrated effects:
* zero-stride or undersized-object infinite loop;
* heap OOB read from the firmware-table buffer.
This is not an active-object UAF, not fixed stale storage, and not a repeated release or refcount mutation. There is no evidence that the OOB read is returned to userspace, sent to a device-visible output, or used to drive a later write. Therefore the primitive is CLASS_C rather than CLASS_A or CLASS_B.
Demonstrated consequence is DoS through hang or crash. Speculative consequences such as privilege escalation or information disclosure are not scored because the patch does not establish a usable disclosure path, write primitive, controlled reclaim, or security-boundary bypass.
ImportantCandidate is NO because this is a constrained parser validation bug with OOB read and DoS symptoms, not a strong corruption or boundary primitive. AutoDowngradeAllowed is YES because no unresolved Important-grade primitive remains after accounting for the malformed firmware parsing risk. ManualReview is still RECOMMENDED because heap OOB reads in firmware parsers can be subtle and product-specific exposure depends on firmware trust assumptions.
Likely operational severity is ordinary to borderline Moderate, not Important, unless external advisory evidence later shows a concrete disclosure path, lower-privilege firmware injection path, or stronger corruption consequence.
5. One-sentence report phrase
A malformed AMD GPU VBIOS VoltageObjectInfo table can make the powerplay parser loop forever or perform an internal heap OOB read, causing a local or firmware-mediated denial of service without a demonstrated privilege escalation or disclosure primitive.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
The issue includes an explicit heap OOB read and firmware parser input, so a brief manual check is useful to confirm product exposure and firmware trust boundaries, but the supplied evidence does not establish an Important-grade primitive.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm/amd/powerplay: fix VoltageObjectInfo zero-stride loop and OOB read [ Upstream
Commit: 83c680de6d41d627c077dedb24f89d9e5be0e2a2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=83c680de6d41d627c077dedb24f89d9e5be0e2a2
Changed files:
drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomctrl.c
drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.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=83c680de6d41d627c077dedb24f89d9e5be0e2a2
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93179 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93179
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:H/UI:N/S:U/C:L/I:N/A:H
The Best / paranoid CVSS score: 5.1
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: 3
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 REGULAR
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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