[CVE-2026-68275][MODERATE REGULAR] drm/amdgpu: check amdgpu_vm_bo_find() result in GET_MAPPING_INFO

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

CVE: CVE-2026-68275
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu: check amdgpu_vm_bo_find() result in GET_MAPPING_INFO
Commit: ddba17b3dfa0efc80d6c98621c2fb7af66adb622
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ddba17b3dfa0efc80d6c98621c2fb7af66adb622
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68275
Analysis date: Mon, 10 Aug 2026 19:08:15 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A local user with AMDGPU render-device access can request mapping information for an unmapped buffer object and trigger a NULL pointer dereference in the GEM ioctl path, causing a kernel DoS without evidence of confidentiality, integrity, or privilege-escalation impact.

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

The original Linux kernel CVE announcement for CVE-2026-68275 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68275

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.

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

CVE-2026-68275	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-476;*CWE-20;CWE-754;BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in the AMDGPU GEM_OP_GET_MAPPING_INFO ioctl occurs because amdgpu_vm_bo_find can return NULL when a buffer object has no mapping in the callers VM. The returned pointer was used by amdgpu_vm_bo_va_for_each_valid_mapping, which dereferences bo_va and can crash the kernel when mapping info is requested for an unmapped BO. For the CVSS the PR:L is used because triggering requires local access to the DRM render device, typically through the render group or equivalent device permissions. The issue is not network reachable and is triggered through a local GPU ioctl rather than remote traffic. Impact is denial of service via kernel oops or kernel crash. No direct confidentiality or integrity impact is assigned because the primitive shown by the patch is a NULL dereference, not UAF, OOB access, or controlled memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4)  SKIP CVE-2026-68275 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	NULLPTR SIMPLEFIX HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  Any local process with access to the AMDGPU DRM render node can issue the ioctl. This is typically a render group user, not full root.

* Reliable kernel crash / strong DoS: +1
  The unchecked NULL `bo_va` is dereferenced through `amdgpu_vm_bo_va_for_each_valid_mapping()`, causing a NULL pointer dereference.

* Broad/default/common subsystem or broadly deployed exposure: +1
  AMDGPU DRM render nodes are common on affected GPU systems and are often exposed to non-root desktop or compute users.

Paranoid-only additional signal:

* Availability impact realistic: +1
  The trigger is simple once render-node access exists: request mapping info for an unmapped BO. If the NULL dereference causes host-wide oops or panic, the availability impact is practical.

Not triggered:

* Generic memory corruption: +0
  The primitive is NULL pointer dereference, not UAF, OOB write, double free, refcount misuse, or type confusion.

* Privilege escalation plausible: +0
  No reclaim, overwrite, callback control, object confusion, or controlled memory corruption is shown.

* Confidentiality / Integrity impact: +0
  No read disclosure or write primitive is supported by the patch.

* Remote reachable: +0
  This is a local DRM ioctl path, not network-triggerable.

## 3. Reachability analysis

The bug is reachable by a local process that can open the AMDGPU DRM render device and issue `AMDGPU_GEM_OP_GET_MAPPING_INFO` for a BO that has not been mapped into the caller VM. This commonly corresponds to users in the `render` group or equivalent device ACLs.

Namespaces or containers may matter if the GPU render node is passed into a container. In that case, a containerized workload with render-device access may be able to trigger the host kernel bug, but this still remains a local device-interface trigger rather than a remote network issue.

The affected path is relevant on systems using AMDGPU with render-node access enabled. Realistic exploitation is a local DoS. There is no evidence of LPE beyond the crash primitive.

Call-site confidence: high. The commit message and diff directly identify the ioctl path, the NULL return from `amdgpu_vm_bo_find()`, and the dereference site.

## 4. Severity interpretation

This behaves like a Borderline / actionable Moderate local DoS, not an Important-class memory corruption issue. Theoretical severity is limited because the demonstrated primitive is a NULL dereference. Realistic impact is kernel oops or crash from a local render-device user.

It should not be upgraded to privilege escalation without additional evidence such as UAF, attacker-controlled reuse, object replacement, arbitrary write, or callback control.

## 5. One-sentence report phrase

A local user with AMDGPU render-device access can request mapping information for an unmapped buffer object and trigger a NULL pointer dereference in the GEM ioctl path, causing a kernel DoS without evidence of confidentiality, integrity, or privilege-escalation impact.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the issue is a simple local NULL dereference, but the render-node exposure is common enough that it should not be blindly auto-closed on GPU-enabled systems.

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

Patch: drm/amdgpu: check amdgpu_vm_bo_find() result in GET_MAPPING_INFO
Commit: ddba17b3dfa0efc80d6c98621c2fb7af66adb622
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ddba17b3dfa0efc80d6c98621c2fb7af66adb622

Commit description:

The AMDGPU_GEM_OP_GET_MAPPING_INFO path of amdgpu_gem_op_ioctl() looks
up the bo_va for the buffer object in the caller's VM via
amdgpu_vm_bo_find(), but uses the returned pointer without checking it.

amdgpu_vm_bo_find() returns NULL when the BO has no bo_va in that VM,
which is the normal case for a BO that has never been mapped. The result
is fed straight into amdgpu_vm_bo_va_for_each_valid_mapping(), which
expands to list_for_each_entry(mapping, &(bo_va)->valids, list) and
dereferences bo_va, causing a NULL pointer dereference.

This is reachable by any process able to issue the ioctl (render group)
simply by requesting mapping info for an unmapped BO.

Return -ENOENT when no bo_va is found, jumping to out_exec so the
drm_exec context and GEM object reference are released.

Fixes: 4d82724 ("drm/amdgpu: Add mapping info option for GEM_OP ioctl")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 528b193 )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.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=ddba17b3dfa0efc80d6c98621c2fb7af66adb622

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

The original Linux kernel CVE announcement for CVE-2026-68275 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68275

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: Not available
  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: 3
  Paranoid ActionableScore: 4

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).