[CVE-2026-98179][LOW] drm/amdgpu: fix rmmio iounmap skipped on device removal [ Upstream

[CVE-2026-98179][LOW] drm/amdgpu: fix rmmio iounmap skipped on device removal [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98179
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu: fix rmmio iounmap skipped on device removal [ Upstream
Commit: e81502d6791df9ecd003bfb2ca44f0d1f1b38439
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e81502d6791df9ecd003bfb2ca44f0d1f1b38439
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98179
Analysis date: Thu, 08 Oct 2026 08:16:04 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-98179 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98179

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-2026-98179	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98179 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both 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:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.4';DESCR 'The amdgpu device removal path can leak one rmmio BAR mapping per driver unload or device removal because drm_dev_enter returns false after drm_dev_unplug. Repeated unload and reload or hot unplug cycles can consume kernel virtual memory resources and may eventually cause denial of service. For the CVSS the PR:H reflects that unloading the amdgpu module or controlling physical device removal normally requires administrative privileges. The issue is not network reachable. Impact is limited to resource exhaustion and there is no memory corruption primitive or direct privilege escalation path.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	INIT SIMPLEFIX LEAK HARDWARE 	-	-	checked

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

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: -1
* Conservative score: 0
* Raw paranoid score: -1
* Paranoid score: 0
* Score was clamped to the minimum ActionableScore value of 0.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete persistent kernel resource leak. One MMIO BAR mapping in adev->rmmio is leaked for every driver unload or device removal because drm_dev_enter returns false after drm_dev_unplug and skips iounmap.
* -2 Host-admin-equivalent privilege requirement. Triggering the repeatable rmmod path requires CAP_SYS_MODULE or equivalent host administrative control. Device hot removal also requires privileged control over the host device lifecycle.
* No resource exhaustion escalation awarded. The patch proves one leaked mapping per unload, but does not establish that a practical number of repetitions exhausts host resources or bypasses resource isolation.
* No memory corruption, UAF, double release, stale dereference, arbitrary write, disclosure, authorization bypass, or privilege escalation primitive is established.
* No remote reachability is established.
* No reliable host crash or device failure is established. The demonstrated effect is a resource leak.

3. Reachability analysis

The directly described trigger is amdgpu module unload through rmmod or PCI device removal. Repeated module unload and reload requires host CAP_SYS_MODULE or equivalent host administrative authority. The hot unplug path also requires control over the relevant host device lifecycle.

This is not a normal DRM render-node, KMS, compositor, or ordinary logged-in desktop-user operation. No evidence establishes that an unprivileged user, DRM master, compositor, delegated graphics service, or namespace-scoped capability can perform the complete unload or removal sequence. Namespace-scoped privilege is therefore NO.

No special rare hardware penalty is applied. AMD GPUs are common hardware, but the vulnerable operation remains an administrative driver-removal path.

4. Primitive and severity interpretation

The exact primitive is a persistent kernel virtual-address-space resource leak caused by a skipped iounmap of the amdgpu register BAR mapping. The mapping remains allocated after device removal or module unload because the teardown code incorrectly depends on drm_dev_enter after drm_dev_unplug has made entry impossible.

This is not an active stale-object use, UAF, DMA ownership defect, double unmap, or repeated lifetime mutation. The fix performs the missing iounmap when adev->rmmio is non NULL and clears the pointer afterward. Repetition can accumulate mappings, but the supplied evidence does not establish practical host-wide resource exhaustion, cross-container impact, or a security-boundary bypass.

PrimitiveClass is NONE because the patch establishes a missing cleanup operation only. ImportantCandidate is NO and AutoDowngradeAllowed is YES because no unresolved kernel-corruption or authorization primitive remains. Operationally, this is a low-priority privileged resource-leak fix that can be handled in normal maintenance.

5. One-sentence report phrase

A missing iounmap in the amdgpu device removal path leaks one MMIO BAR mapping per driver unload or device removal, requiring repeated host administrative actions to cause resource exhaustion.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes a privileged persistent resource leak without memory corruption, a security-boundary bypass, or a demonstrated practical host-wide denial of service.

7. Call-site confidence

Call-site confidence: high

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

Patch: drm/amdgpu: fix rmmio iounmap skipped on device removal [ Upstream
Commit: e81502d6791df9ecd003bfb2ca44f0d1f1b38439
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e81502d6791df9ecd003bfb2ca44f0d1f1b38439

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_device.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=e81502d6791df9ecd003bfb2ca44f0d1f1b38439

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

The original Linux kernel CVE announcement for CVE-2026-98179 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98179

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:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.4

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).