[CVE-2026-68248][MODERATE REGULAR] drm/i915: Return NULL on error in active_instance

[CVE-2026-68248][MODERATE REGULAR] drm/i915: Return NULL on error in active_instance

[AL-KERNEL]

CVE: CVE-2026-68248
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/i915: Return NULL on error in active_instance
Commit: 32c1a2afa90dd07df931f0b12578de1dbb751f0c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=32c1a2afa90dd07df931f0b12578de1dbb751f0c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68248
Analysis date: Mon, 10 Aug 2026 18:00:18 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline Ordinary Moderate. Not an Important candidate
Manual review required: NO

Summary:
A local user with access to the i915 DRM interface may trigger an allocation-failure path where `active_instance()` returns an invalid pointer derived from a NULL object, causing a kernel crash and denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-68248 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68248

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: NO

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-2026-68248	MODERATE	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-476;CWE-252;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'active_instance in the i915 driver could return an invalid pointer derived from node base when a GFP_ATOMIC allocation fails and node is NULL. A local process with access to the i915 DRM interface may then drive a later dereference of this invalid pointer, causing a kernel crash and denial of service. For the CVSS the PR:L is used because reliable triggering requires local code execution and access to the GPU device interface, which is commonly available through /dev/dri render nodes or device group policy. The issue is not network reachable. Impact is denial of service only. The patch context indicates NULL pointer dereference behavior rather than UAF, OOB write, or an arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Borderline Ordinary Moderate. Not an Important candidate (with actual score 3)	YES	LOCK SIMPLEFIX HARDWARE  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline Ordinary Moderate. Not an Important candidate**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process with access to the i915 DRM interface may reach this path through normal GPU usage, often via `/dev/dri` render nodes.
* Reliable kernel crash / strong DoS: +1. Returning `&node->base` when `node == NULL` can lead to an invalid pointer dereference and kernel crash.
* Broad/default/common subsystem: +1. i915 is widely deployed on Intel GPU systems.
* Hard or unreliable condition: -1. Triggering depends on a `GFP_ATOMIC` allocation failure, usually requiring memory pressure or a narrow allocator state.
* Weak corruption only: +0. This is best treated as NULL/low-address invalid pointer dereference, not UAF, OOB write, arbitrary write, or object replacement.

Paranoid difference:

* The paranoid score does not subtract the hard-trigger condition, assuming a local user can make memory pressure and GPU activity sufficiently repeatable.

No points awarded for:

* Remote reachability. The path is local only.
* Privilege escalation. No reclaim, overwrite, type confusion, callback control, or refcount takeover is shown.
* Generic strong memory corruption. The patch fixes an invalid return value on allocation failure, not a demonstrated corruption primitive.
* High-control GPU API bonus. The patch does not show attacker control over memory lifetime, callback targets, refcounts, DMA ownership, or object replacement.

## 3. Reachability analysis

The likely trigger is a local process that can access the i915 DRM device and exercise the relevant active fence or execbuf-related path while a `GFP_ATOMIC` allocation fails. On many desktop systems, render nodes are available to ordinary local users through `/dev/dri/renderD*` or group policy, so PR:L is a reasonable CVSS interpretation.

The issue is not network reachable. Containers only matter if the GPU device node is passed through or delegated into the container. In typical deployments without GPU device access, an untrusted container cannot trigger it directly.

The path is common on Intel GPU systems, but the exact failure condition is OOM or atomic allocation failure, so exploit reliability is limited.

## 4. Severity interpretation

This behaves like an ordinary Moderate local DoS. The theoretical bug is an invalid pointer return after allocation failure, but the realistic consequence is a kernel crash when that invalid pointer is later dereferenced.

There is no evidence of UAF, double free, OOB write, arbitrary write, attacker-controlled reclaim, or type confusion. Therefore it should not be treated as an Important-class memory corruption issue based on the provided patch.

## 5. One-sentence report phrase

A local user with access to the i915 DRM interface may trigger an allocation-failure path where `active_instance()` returns an invalid pointer derived from a NULL object, causing a kernel crash and denial of service.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

This is not urgent Important-class material, but a lightweight manual check is reasonable because i915 is widely deployed and local DRM access is often available to unprivileged users. The expected final disposition is local DoS only unless additional evidence shows a real memory corruption or privilege escalation primitive.

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

Patch: drm/i915: Return NULL on error in active_instance
Commit: 32c1a2afa90dd07df931f0b12578de1dbb751f0c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=32c1a2afa90dd07df931f0b12578de1dbb751f0c

Commit description:

Avoid returning &node->base when node is NULL due to OOM
during GFP_ATOMIC allocation.

Discovered using AI-assisted static analysis confirmed by
Intel Product Security.

Reported-by: Martin Hodo <martin.hodo@intel.com>
Fixes: bfaae47 ("drm/i915: make lockdep slightly happier about execbuf.")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Simona Vetter <simona.vetter@ffwll.ch>
Cc: <stable@vger.kernel.org> # v5.13+
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patch.msgid.link/20260624090940.74840-1-joonas.lahtinen@linux.intel.com
(cherry picked from commit 6029bc0 )
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/i915/i915_active.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=32c1a2afa90dd07df931f0b12578de1dbb751f0c

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

The original Linux kernel CVE announcement for CVE-2026-68248 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68248

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: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: 2
  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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).