[CVE-2026-68242][MODERATE REGULAR] drm/i915/gt: Fix NULL deref on sched_engine alloc failure

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

CVE: CVE-2026-68242
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/i915/gt: Fix NULL deref on sched_engine alloc failure
Commit: edd4804f07b8369ed472de19272974e2bf2a6271
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=edd4804f07b8369ed472de19272974e2bf2a6271
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68242
Analysis date: Mon, 10 Aug 2026 10:03:13 -0400
ActionableScore: 2
ActionableScore lower bound: 2
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A local user with access to the i915 DRM IOCTL path may trigger a NULL pointer dereference during virtual engine creation if sched_engine allocation fails before context initialization, causing a kernel crash or oops.

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

The original Linux kernel CVE announcement for CVE-2026-68242 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68242

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
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CVE-2026-68242	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-476;CWE-665;CWE-755;BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the i915 virtual engine creation IOCTL path when i915_sched_engine_create fails before intel_context_init has initialized the embedded context. The error path previously called intel_context_put too early, so kref based cleanup could dereference invalid or NULL context state and crash the kernel. For the CVSS the PR:L is used because a local user or process with access to the DRM i915 device node can reach the IOCTL path, but reliable triggering also depends on causing or hitting a sched_engine allocation failure. The issue is not network reachable. Impact is local denial of service via kernel crash or oops, with no concrete evidence of information disclosure, arbitrary write, UAF, or privilege escalation from this patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-68242 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	NOMEMCHK SIMPLEFIX HARDWARE 	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=2

## 1. ActionableScore

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

## 2. Signal breakdown

Triggered signals:

* **Local unprivileged trigger: +1**
  The affected path is an i915 DRM IOCTL path. On many systems, local users in the graphics/render group can access `/dev/dri/renderD*` or similar DRM nodes.

* **Reliable kernel crash / strong DoS: +1**
  If `i915_sched_engine_create()` fails before `intel_context_init()`, the old error path calls `intel_context_put()` too early and can hit a NULL pointer dereference.

Subtract / not awarded:

* **Hard or unreliable trigger: -1 considered but not applied to final score separately**
  Reliable triggering depends on hitting a specific allocation failure in `sched_engine` creation. This makes exploitation less practical, but the final score is already low and not elevated.

* **No generic memory corruption: +0**
  The patch supports a NULL dereference on an error path, not UAF, OOB write, double free, type confusion, or arbitrary write.

* **No privilege escalation plausible: +0**
  There is no demonstrated reclaim, stale object reuse, callback dispatch, controlled overwrite, refcount takeover, or other LPE-relevant primitive.

* **No confidentiality or integrity impact: +0**
  The supported impact is crash/oops only.

* **No network reachability: +0**
  This is a local DRM IOCTL path, not remotely triggerable.

## 3. Reachability analysis

A local process with access to the i915 DRM device node can reach the affected IOCTL path. This may be unprivileged on desktop or graphics-enabled systems where render nodes are exposed to users, but it is still a local attack surface and not a network one.

The practical trigger requires `i915_sched_engine_create()` to fail at a specific point before `intel_context_init()`. That usually means memory pressure or allocation-failure conditions, so reliable exploitation is less straightforward than a normal always-triggerable NULL dereference.

Namespaces and containers may matter if GPU device nodes are passed through to a container. In that case, a container user with access to the DRM node could potentially trigger the bug, but this still remains a local device-interface DoS.

## 4. Severity interpretation

This behaves like an **ordinary Moderate / Low-like local DoS**, not an Important-class kernel vulnerability.

The theoretical bug class is an invalid cleanup path on a partially initialized object. The realistic evidence from the patch is a NULL pointer dereference through `intel_context_put()` before `intel_context_init()`, not a UAF or controllable memory corruption primitive. There is no supported path to information disclosure, integrity violation, or privilege escalation.

## 5. One-sentence report phrase

A local user with access to the i915 DRM IOCTL path may trigger a NULL pointer dereference during virtual engine creation if sched_engine allocation fails before context initialization, causing a kernel crash or oops.

## 6. Manual review recommendation

**MANUAL CHECK RECOMMENDED**

Reason: the actionable score is low and the patch only supports local DoS, but the bug is in a broadly deployed GPU driver IOCTL path and was confirmed by Intel Product Security, so a lightweight manual review is reasonable before auto-closing.

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

Patch: drm/i915/gt: Fix NULL deref on sched_engine alloc failure
Commit: edd4804f07b8369ed472de19272974e2bf2a6271
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=edd4804f07b8369ed472de19272974e2bf2a6271

Commit description:

Avoid using intel_context_put() before intel_context_init() in
execlists_create_virtual() as the kref_put() inside would lead
to NULL deref on the IOCTL path when sched_engine allocation fails.

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

Reported-by: Martin Hodo <martin.hodo@intel.com>
Fixes: 3e28d37 ("drm/i915: Move priolist to new i915_sched_engine object")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: <stable@vger.kernel.org> # v5.15+
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20260701114513.221254-1-joonas.lahtinen@linux.intel.com
(cherry picked from commit 4f2a12f )
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/i915/gt/intel_execlists_submission.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=edd4804f07b8369ed472de19272974e2bf2a6271

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

The original Linux kernel CVE announcement for CVE-2026-68242 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68242

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: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: 2
  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: 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).