[CVE-2026-68261][MODERATE REGULAR] drm/imagination: fix error checking of pvr_vm_context_lookup()

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

CVE: CVE-2026-68261
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/imagination: fix error checking of pvr_vm_context_lookup()
Commit: ce97192087c659f2e0c0c2a627330c7edcc9eeb3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ce97192087c659f2e0c0c2a627330c7edcc9eeb3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68261
Analysis date: Mon, 10 Aug 2026 18:35:02 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate / Manual review recommended
Manual review required: YES

Summary:
A local user with access to the PowerVR DRM device can pass an invalid VM context handle to DRM_IOCTL_PVR_CREATE_CONTEXT, causing a NULL pointer dereference in the context creation path and a kernel Oops or crash.

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

The original Linux kernel CVE announcement for CVE-2026-68261 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68261

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-2026-68261	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-253;**CWE-476;*CWE-20;BEST CVSS score: '5.5';DESCR 'An incorrect return value check in drm/imagination context creation can leave ctx vm_ctx as NULL when userspace passes an invalid VM context handle to DRM_IOCTL_PVR_CREATE_CONTEXT. The code used IS_ERR even though pvr_vm_context_lookup returns NULL or a valid pointer, so the invalid handle path continued and later dereferenced the NULL VM context in pvr_vm_get_fw_mem_context. For the CVSS the PR:L is used because a local process must be able to open the PowerVR DRM device and issue the ioctl, which is commonly available to local users with render or graphics device access. The issue is not network reachable. Impact is denial of service via kernel oops or crash. There is no supported privilege escalation or information disclosure primitive because the patch shows a NULL pointer dereference rather than UAF, OOB write, or stale pointer traversal.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate / Manual review recommended (with actual score 3)  SKIP CVE-2026-68261 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB NULLPTR HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline Moderate / Manual review recommended**::

## 2. Signal breakdown

* Local unprivileged trigger: +1. A local process with access to the PowerVR DRM device can pass an invalid VM context handle to `DRM_IOCTL_PVR_CREATE_CONTEXT`.
* Reliable kernel crash / strong DoS: +1. The commit includes a concrete reproducible NULL pointer dereference and kernel Oops in `pvr_vm_get_fw_mem_context`.
* Availability impact realistic: +1 in paranoid scoring only. The trigger is simple and repeatable on affected systems, and may become host-wide DoS depending on oops handling or `panic_on_oops`.
* No generic memory corruption: +0. The patch shows NULL dereference, not UAF, OOB write, double free, stale callback, refcount misuse, or type confusion.
* No privilege escalation signal: +0. There is no reclaim, overwrite, callback control, or object replacement primitive.
* No confidentiality or integrity impact: +0. No leak or write primitive is shown.
* No high-control device API bonus: +0. This is a DRM ioctl object validation bug, but the patch does not show attacker control over memory layout, lifetime, refcounts, DMA mappings, or callbacks.
* Rare hardware exposure: 0. The affected driver is hardware-specific, but on systems with this GPU the ioctl path is an ordinary local DRM interface.

Call-site confidence: high. The patch, ioctl path, and crash stack are all present.

## 3. Reachability analysis

The bug is locally reachable through `DRM_IOCTL_PVR_CREATE_CONTEXT` by passing an invalid VM context handle. In typical desktop or embedded GPU deployments, DRM render or graphics device nodes may be accessible to non-root local users, so PR:L is the practical CVSS interpretation. It is not network reachable. Containers or sandboxes matter only if the DRM device node is passed through to the container. The path is enabled only on systems using the Imagination PowerVR DRM driver.

## 4. Severity interpretation

This behaves like an ordinary to borderline actionable Moderate local DoS. The realistic impact is kernel Oops or crash from a NULL pointer dereference. Theoretical privilege escalation is not supported by the patch because the bad value is NULL, not a freed or attacker-controlled object pointer. It should not be treated as Important-class memory corruption, but it also should not be blindly auto-closed on affected systems where unprivileged users can access the DRM node.

## 5. One-sentence report phrase

A local user with access to the PowerVR DRM device can pass an invalid VM context handle to DRM_IOCTL_PVR_CREATE_CONTEXT, causing a NULL pointer dereference in the context creation path and a kernel Oops or crash.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED. Verify whether the affected product exposes the PowerVR DRM device to unprivileged users, and whether kernel oops handling makes this a practical host-wide DoS.

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

Patch: drm/imagination: fix error checking of pvr_vm_context_lookup()
Commit: ce97192087c659f2e0c0c2a627330c7edcc9eeb3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ce97192087c659f2e0c0c2a627330c7edcc9eeb3

Commit description:

Since pvr_vm_context_lookup() returns either NULL or a pointer, then stop
using IS_ERR() for checking the return value.

Using IS_ERR() leads to the kernel oops reported below. It can be
reproduced by passing an invalid VM context handle from userspace to the
DRM_IOCTL_PVR_CREATE_CONTEXT ioctl.

[   92.733119] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000148
[   92.742042] Mem abort info:
[   92.744890]   ESR = 0x0000000096000004
[   92.748686]   EC = 0x25: DABT (current EL), IL = 32 bits
[   92.754020]   SET = 0, FnV = 0
[   92.757154]   EA = 0, S1PTW = 0
[   92.760337]   FSC = 0x04: level 0 translation fault
[   92.765243] Data abort info:
[   92.768129]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[   92.773626]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[   92.778763]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[   92.784098] user pgtable: 4k pages, 48-bit VAs, pgdp=000000088ed23000
[   92.790550] [0000000000000148] pgd=0000000000000000, p4d=0000000000000000
[   92.797381] Internal error: Oops: 0000000096000004 [#1]  SMP
[   92.803027] Modules linked in: powervr
[   92.852533] CPU: 0 UID: 0 PID: 409 Comm: triangle Not tainted 7.1.0-rc5-g98b46e693b91 #1 PREEMPT
[   92.861385] Hardware name: Texas Instruments AM68 SK (DT)
[   92.866766] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   92.873709] pc : pvr_vm_get_fw_mem_context+0x0/0xc [powervr]
[   92.879376] lr : pvr_queue_create+0x26c/0x440 [powervr]
[   92.884595] sp : ffff8000837fbb00
[   92.887895] x29: ffff8000837fbb60 x28: 0000000000000000 x27: ffff8000837fbce8
[   92.895015] x26: ffff000807f61a40 x25: ffff000807f61a00 x24: ffff000807f64400
[   92.902135] x23: ffff00080a5ab000 x22: ffff800079b24730 x21: ffff000807f61800
[   92.909254] x20: ffff00080999e680 x19: 0000000000000000 x18: 0000000000000000
[   92.916373] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
[   92.923492] x14: 0000000000000000 x13: 0000000000000002 x12: ffff80008145b298
[   92.930611] x11: ffff8000844e5000 x10: ffff80008165a130 x9 : 0000000000000100
[   92.937730] x8 : 0000000000000001 x7 : ffff0008076b27e0 x6 : ffff00080ec43b7c
[   92.944850] x5 : ffff00080ec43b78 x4 : 0000000000000000 x3 : ffff00080999e680
[   92.951968] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[   92.959088] Call trace:
[   92.961521]  pvr_vm_get_fw_mem_context+0x0/0xc [powervr] (P)
[   92.967173]  pvr_context_create+0x190/0x410 [powervr]
[   92.972218]  pvr_ioctl_create_context+0x44/0x8c [powervr]
[   92.977608]  drm_ioctl_kernel+0xbc/0x124 [drm]
[   92.982127]  drm_ioctl+0x1f8/0x4dc [drm]
[   92.986098]  __arm64_sys_ioctl+0xac/0x104
[   92.990102]  invoke_syscall+0x54/0x10c
[   92.993842]  el0_svc_common.constprop.0+0x40/0xe0
[   92.998532]  do_el0_svc+0x1c/0x28
[   93.001835]  el0_svc+0x38/0x11c
[   93.004969]  el0t_64_sync_handler+0xa0/0xe4
[   93.009139]  el0t_64_sync+0x198/0x19c
[   93.012792] Code: aa1703e0 d2800014 95cb0ba4 17ffffe8 (f940a400)
[   93.018869] ---[ end trace 0000000000000000 ]---

Fixes: d2d79d2 ("drm/imagination: Implement context creation/destruction ioctls")
Cc: stable@vger.kernel.org
Signed-off-by: Luigi Santivetti <luigi.santivetti@imgtec.com>
Reviewed-by: Alessio Belle <alessio.belle@imgtec.com>
Link: https://patch.msgid.link/20260707-staging-ddkopsrc-2435-v1-1-24e160d44476@imgtec.com
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_context.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=ce97192087c659f2e0c0c2a627330c7edcc9eeb3

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

The original Linux kernel CVE announcement for CVE-2026-68261 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68261

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: 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).