[CVE-2026-68264][IMPORTANT] drm/xe/pt: Reset current_op in xe_pt_update_ops_init() [ Upstream

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

CVE: CVE-2026-68264
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: drm/xe/pt: Reset current_op in xe_pt_update_ops_init() [ Upstream
Commit: be5c39730ab8f1dfe59983bf7d8e3705541d1fee
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=be5c39730ab8f1dfe59983bf7d8e3705541d1fee
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68264
Analysis date: Mon, 10 Aug 2026 16:23:41 -0400
ActionableScore: 7
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A missing reset of `current_op` in the DRM Xe page-table update retry path can cause an out-of-bounds write into kernel heap memory and a later UAF crash, making this a local DoS with plausible privilege-escalation concern for users able to access the Xe DRM render node.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68264 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68264

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: IMPORTANT
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
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CVE-2026-68264	IMPORTANT	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;*CWE-416;CWE-665;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A memory corruption bug in the drm xe page table update path can occur because xe_pt_update_ops_init did not reset current_op before a retry of the vm_bind prepare path. When drm_exec retries after lock contention or OOM eviction, bind_op_prepare can increment current_op again on the same vops object until it exceeds the array allocated for page table operations. This creates an out of bounds write into SLUB poisoned memory and can later crash in xe_migrate_update_pgtables_cpu when the corrupted pt_op bind pointer is read. For the CVSS the PR:L is used because a local user or process with access to the DRM xe render node may be able to reach vm_bind style GPU VM operations without full administrator privileges. The issue is not network reachable. Impact is at least local denial of service via kernel crash, and in the paranoid case may include confidentiality and integrity impact because the patch context explicitly indicates kernel heap out of bounds write and UAF symptoms.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	WRITE OOB DANGER UAF KERNEL_PANIC_PLUS_UAF HARDWARE KPANIC 	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=6

## 1. ActionableScore

* Conservative score: **6**
* Paranoid score: **7**
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

**Triggered positive signals:**

* **Local unprivileged trigger: +1**
  The vulnerable path is the DRM Xe `vm_bind` path, which is commonly reachable through DRM render node access by local users or GPU workloads without full host root.

* **Memory corruption, strong corruption primitive: +2**
  The commit explicitly states that `current_op` can exceed the array size allocated by `xe_vma_ops_alloc()`, causing an **out-of-bounds write** into SLUB-poisoned memory.

* **Real lifetime corruption: +1**
  The commit describes a subsequent **UAF crash** in `xe_migrate_update_pgtables_cpu()` when reading the corrupted `pt_op->bind`.

* **Reliable kernel crash / strong DoS: +1**
  The described outcome includes a kernel crash after heap corruption and UAF symptoms.

* **Weak to strong LPE concern: +1 conservative / +2 paranoid**
  Conservative scoring treats this as a plausible but not demonstrated LPE concern because the OOB write target and payload control are not fully shown. Paranoid scoring raises this to +2 because a kernel heap OOB write in a local DRM VM bind path is a credible privilege-escalation candidate and historically deserves manual review.

* **Local device memory-management path with attacker-shaped operations: +1**
  The bug occurs in GPU page-table update operation construction, where userspace can plausibly influence VM bind operation shape and retry behavior through DRM interfaces.

**Triggered negative signals:**

* **Hard or unreliable race / special timing required: -1**
  The overflow requires repeated retry of the same prepare path due to lock contention or OOM eviction. This is not a simple single-call trigger.

## 3. Reachability analysis

The bug is **local**, not network reachable. A local user or process with access to the Intel Xe DRM render node may be able to reach the `vm_bind` operation path without full administrative privileges. In many desktop, workstation, and GPU compute environments, render nodes are intentionally exposed to non-root users through device permissions or groups.

Namespaces and containers can matter if `/dev/dri/renderD*` is passed through to a container or workload. In that case, a containerized or reduced-privilege process may still reach the vulnerable kernel driver path. The trigger requires retry behavior from `drm_exec` due to lock contention or OOM eviction, so exploitation is less straightforward than a deterministic ioctl crash, but the commit describes a concrete OOB write and UAF crash path.

## 4. Severity interpretation

This is **not an ordinary Moderate correctness bug**. The patch context explicitly describes kernel heap memory corruption: an out-of-bounds write past an allocated operation array, followed by a UAF-style crash when the corrupted `pt_op->bind` is read.

Realistically demonstrated impact is local kernel crash / DoS. However, the corruption occurs in a local DRM page-table update path with user-influenced GPU VM operations, so privilege escalation is technically plausible and should not be auto-closed. Conservative handling is **Actionable Moderate**, while paranoid handling is a **Strong Important candidate**.

## 5. One-sentence report phrase

A missing reset of `current_op` in the DRM Xe page-table update retry path can cause an out-of-bounds write into kernel heap memory and a later UAF crash, making this a local DoS with plausible privilege-escalation concern for users able to access the Xe DRM render node.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

Reason: explicit OOB write plus UAF crash symptoms in a local DRM memory-management path. Even though exploitation requires retry timing and no working LPE primitive is demonstrated, this class should receive manual kernel-security review rather than automatic Moderate closure.

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

Patch: drm/xe/pt: Reset current_op in xe_pt_update_ops_init() [ Upstream
Commit: be5c39730ab8f1dfe59983bf7d8e3705541d1fee
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=be5c39730ab8f1dfe59983bf7d8e3705541d1fee

Changed files:
  drivers/gpu/drm/xe/xe_pt.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=be5c39730ab8f1dfe59983bf7d8e3705541d1fee

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

The original Linux kernel CVE announcement for CVE-2026-68264 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68264

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 6
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).