[CVE-2026-68260][MODERATE REGULAR] drm/imagination: acquire vm_ctx->lock before mapping memory to GPU VM

[CVE-2026-68260][MODERATE REGULAR] drm/imagination: acquire vm_ctx->lock before mapping memory to GPU VM

[AL-KERNEL]

CVE: CVE-2026-68260
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/imagination: acquire vm_ctx->lock before mapping memory to GPU VM
Commit: 1f1f2618e44b21a7d4eb30d3bbd7e015ffbbbadf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f1f2618e44b21a7d4eb30d3bbd7e015ffbbbadf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68260
Analysis date: Mon, 10 Aug 2026 11:56:25 -0400
ActionableScore: 4
ActionableScore lower bound: 2
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A local race in the drm/imagination GPU VM map path can let a process with DRM device access disturb concurrent GPUVA lookup or unmap operations and trigger a NULL pointer dereference in `drm_gpuva_find`, causing a kernel crash, with no demonstrated UAF or arbitrary write primitive.

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

The original Linux kernel CVE announcement for CVE-2026-68260 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68260

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.

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

CVE-2026-68260	MODERATE	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:L/I:L/A:H';CWE-362;CWE-667;**CWE-476;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'A race in the drm imagination GPU VM path can occur because pvr_vm_map did not take vm_ctx lock while drm_gpuva_find operations are expected to be protected by that lock. A local process with access to the DRM device can race GPU VM map and find or unmap activity and trigger a NULL pointer dereference in drm_gpuva_find, causing a kernel crash and denial of service. For the CVSS the PR:L is selected because an attacker needs local user access to the DRM device or render node to issue the relevant ioctls, but full administrator privileges are not normally required. The issue is not network reachable and requires local interaction with the GPU driver control interface. The observed failure is a NULL pointer dereference rather than a proven UAF or arbitrary write. Impact is at least local denial of service, and the paranoid score keeps limited confidentiality and integrity impact because the bug is a kernel race in VM metadata and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3)  SKIP CVE-2026-68260 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB LOCK NULLPTR HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=4
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process with access to the DRM device or render node can issue the relevant ioctls.
* Reliable kernel crash / strong DoS: +1. The commit includes a concrete NULL pointer dereference stack trace in `drm_gpuva_find`.
* Hard or unreliable race / special timing required: -1. Triggering requires racing GPU VM map with find or unmap activity.
* Weak/indirect corruption candidate: +1. The missing lock allows concurrent modification of GPU VM metadata during lookup, but the demonstrated primitive is only NULL dereference.

Paranoid additional signals:

* Weak LPE concern: +1. The affected objects are GPU VM metadata, and the bug is a synchronization flaw around map/find/unmap operations, so manual review is justified even though no UAF, overwrite, callback control, or reclaim primitive is shown.
* Privileged kernel/device-management memory corruption path: +1. The affected code manages GPU virtual memory mappings in a trusted kernel driver path. This is not enough for Important by itself, but it raises review priority.

Not applied:

* Remote reachable: +0. This is not network-triggerable.
* Strong memory corruption primitive: +0. The patch and trace show NULL dereference, not UAF, OOB write, double-free, arbitrary write, or type confusion.
* Strong LPE plausibility: +0. No attacker-controlled reclaim, object replacement, write-after-free, callback dispatch, or refcount takeover is demonstrated.
* High-control kernel data-plane API: +0. GPU ioctls alone are not enough under the provided RDMA/device-object API rule.

## 3. Reachability analysis

A local user process can potentially trigger this through the PowerVR DRM ioctl path if it has access to the affected DRM device node. Full root privileges are not normally required when render node access is granted, so PR:L is the practical interpretation. Containers may matter if DRM device nodes are passed through to the container, but without such device access the bug is not reachable.

The affected path is not remotely reachable and requires the specific `drm/imagination` PowerVR driver and hardware or platform support. Exploitation requires a race between GPU VM map and find/unmap paths, so reliability is lower than a direct validation bug.

Call-site confidence: medium. The provided stack trace shows the ioctl-to-`drm_gpuva_find` crash path, but the full surrounding GPU VM data structure behavior is not included.

## 4. Severity interpretation

This behaves more like a borderline actionable Moderate than an Important-class issue. The realistic demonstrated impact is local kernel crash and denial of service via NULL pointer dereference. The theoretical concern is that the race affects GPU VM metadata, but the patch does not demonstrate a concrete memory corruption primitive suitable for privilege escalation.

The conservative score remains low because this is local, race-dependent, hardware/driver-specific, and currently demonstrated as NULL dereference only. The paranoid score reaches manual-review territory because synchronization bugs in GPU VM mapping code can sometimes hide more serious stale-object or metadata-consistency issues.

## 5. One-sentence report phrase

A local race in the drm/imagination GPU VM map path can let a process with DRM device access disturb concurrent GPUVA lookup or unmap operations and trigger a NULL pointer dereference in `drm_gpuva_find`, causing a kernel crash, with no demonstrated UAF or arbitrary write primitive.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the demonstrated impact is DoS only, but the race is in GPU VM metadata and the paranoid score is high enough to avoid automatic closure until a human confirms there is no stale pointer, UAF, or metadata corruption path beyond NULL dereference.

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

Patch: drm/imagination: acquire vm_ctx->lock before mapping memory to GPU VM
Commit: 1f1f2618e44b21a7d4eb30d3bbd7e015ffbbbadf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f1f2618e44b21a7d4eb30d3bbd7e015ffbbbadf

Commit description:

The drm gpuvm code doesn't protect find operation against map operation,
and the driver needs to ensure a map operation shouldn't happen when a
find operation is in progress.

In some cases a find operation will be in progress when doing map/unmap
operations, and the find operation will do a NULL pointer dereference.

An example of the stack trace of such NULL dereference is shown below:

```
Unable to handle kernel access to user memory without uaccess routines at
virtual address 0000000000000010

[<ffffffff01e989d4>] drm_gpuva_find+0x28/0x6c [drm_gpuvm]
[<ffffffff01ed3a40>] pvr_vm_unmap+0x34/0x68 [powervr]
[<ffffffff01ec69da>] pvr_ioctl_vm_unmap+0x2e/0x50 [powervr]
[<ffffffff8080ce0a>] drm_ioctl_kernel+0x8e/0xdc
[<ffffffff8080d016>] drm_ioctl+0x1be/0x3e0
[<ffffffff802bec3e>] __riscv_sys_ioctl+0xba/0xc4
[<ffffffff80d858b2>] do_trap_ecall_u+0x23e/0x3f4
[<ffffffff80d92288>] handle_exception+0x168/0x174
```

As all occurences of drm_gpuva_find*() are already guarded by
vm_ctx->lock, make pvr_vm_map() to acquire this lock to prevent
disturbing any find operation. This fixes the NULL deference problem in
drm_gpuva_find*().

Cc: stable@vger.kernel.org
Fixes: ff5f643 ("drm/imagination: Add GEM and VM related code")
Fixes: 4bc736f ("drm/imagination: vm: make use of GPUVM's drm_exec helper")
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Alessio Belle <alessio.belle@imgtec.com>
Link: https://patch.msgid.link/20260714073641.1935075-1-zhengxingda@iscas.ac.cn
Signed-off-by: Alessio Belle <alessio.belle@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/imagination/pvr_vm.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=1f1f2618e44b21a7d4eb30d3bbd7e015ffbbbadf

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

The original Linux kernel CVE announcement for CVE-2026-68260 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68260

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:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 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).