[CVE-2026-68234][LOW] drm/amdgpu: fix bo->pin leaking in amdgpu_bo_create_reserved

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

CVE: CVE-2026-68234
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu: fix bo->pin leaking in amdgpu_bo_create_reserved
Commit: 51eeef1949c11d3dcb5f422a5d9b3f09ebe8a1bc
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=51eeef1949c11d3dcb5f422a5d9b3f09ebe8a1bc
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68234
Analysis date: Mon, 10 Aug 2026 12:28:07 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-68234 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68234

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: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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

CVE-2026-68234	LOW	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-772;**CWE-400;CWE-404;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'amdgpu_bo_create_reserved could increase bo pin_count repeatedly when the same non NULL BO pointer was reused during firmware buffer reload paths such as resume, cp_resume, or start with AMDGPU_FW_LOAD_DIRECT. The matching teardown only unpins once, so the BO may remain permanently pinned and TTM may be unable to move, swap, or evict it. For the CVSS the PR:L is used for the paranoid score because a local user or local service with access to GPU activity or power management paths may be able to cause repeated reset or resume style operations in some deployments. The issue is not network reachable and is not a memory corruption primitive. Impact is denial of service through GPU resource exhaustion or degraded memory management, with no supported confidentiality or integrity impact.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-68234 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	LEAK ERRORPATH HARDWARE 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1

1. ActionableScore
* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**

2. Signal breakdown
* Availability impact realistic: +1. Repeated BO pin reference leaks can prevent TTM from moving, swapping, or evicting affected BOs, causing GPU memory management degradation.
* Broad/common driver exposure: +1 in paranoid scoring. amdgpu is widely deployed on AMD GPU systems, although this exact path is narrower.
* Local trigger possibility: +1 in paranoid scoring. A local user or local service may be able to contribute to repeated GPU reset, resume, or firmware reload paths in some deployments.
* Legacy / non-default or narrow execution condition: -1. The issue depends on repeated reuse of existing firmware BOs, especially AMDGPU_FW_LOAD_DIRECT resume / cp_resume / start paths.
* No memory corruption signal: +0. The patch shows pin_count leaking, not UAF, double free, OOB write, type confusion, or attacker-controlled overwrite.
* No LPE signal: +0. There is no demonstrated reclaim, arbitrary write, callback control, credential impact, or privilege boundary bypass.
* No confidentiality or integrity signal: +0. The effect is resource retention and eviction failure, not data disclosure or unauthorized modification.

3. Reachability analysis
The bug is reachable through amdgpu internal firmware buffer reload paths when the same non NULL BO pointer is passed again to amdgpu_bo_create_reserved. Typical triggering requires an AMD GPU using the affected path plus repeated resume, cp_resume, start, or similar reset/reinitialization activity. It is not network reachable. Namespaces and containers do not materially improve reachability unless the environment delegates GPU reset or power management control to an untrusted local workload. In normal deployments, triggering is more likely through local system activity, desktop power management, driver recovery, or privileged management operations than through a direct unprivileged API.

4. Severity interpretation
This behaves like an ordinary Moderate or Low-like resource leak rather than an Important kernel vulnerability. The realistic impact is denial of service or degraded GPU memory management after repeated triggering. Theoretical escalation is not supported because the patch only fixes an unmatched pin reference count and does not show memory corruption, stale pointer use, page ownership violation, or a privilege boundary bypass.

5. One-sentence report phrase
A BO pin reference leak in amdgpu_bo_create_reserved can keep reused firmware BOs permanently pinned across repeated resume or reset style reload paths, potentially causing GPU resource exhaustion or degraded memory management without evidence of memory corruption or privilege escalation.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED.
Reason: this is a constrained resource leak with no demonstrated memory corruption, no network reachability, no sensitive data exposure, and no plausible privilege escalation primitive in the provided patch context.

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

Patch: drm/amdgpu: fix bo->pin leaking in amdgpu_bo_create_reserved
Commit: 51eeef1949c11d3dcb5f422a5d9b3f09ebe8a1bc
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=51eeef1949c11d3dcb5f422a5d9b3f09ebe8a1bc

Commit description:

amdgpu_bo_create_reserved() only allocates a new BO when
*bo_ptr (struct amdgpu_bo **bo_ptr as input parameter) is
NULL, it simply skips creation when *bo_ptr is non-NULL.
But it unconditionally reserves, pins, gart allocates
and maps the BO afterwards.

When the same non-NULL BO pointer is passed in again,
for example firmware buffers that live in adev and are
re-loaded on every resume / cp_resume / start
under AMDGPU_FW_LOAD_DIRECT, amdgpu_bo_pin() just increases
pin_count unconditionally, however the matching teardown only unpins
once, so pin_count never drops to zero, so TTM is not able
to move, swap or evict a BO, causing BO leaks.

This commit fixes this issue by only pinning the bo
once at creation, and repeated calls no longer
take additional pin references.

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3ddc0ae )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_object.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=51eeef1949c11d3dcb5f422a5d9b3f09ebe8a1bc

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

The original Linux kernel CVE announcement for CVE-2026-68234 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68234

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: 1
  Paranoid ActionableScore: 2

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).