[CVE-2025-71130][MODERATE 7.0] drm/i915/gem: Zero-initialize the eb.vma array in i915_gem_do_execbuffer

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

CVE: CVE-2025-71130
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: drm/i915/gem: Zero-initialize the eb.vma array in i915_gem_do_execbuffer
Commit: 25d69e07770745992387c016613fd7ac8eaf9893
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25d69e07770745992387c016613fd7ac8eaf9893
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71130
Analysis date: Sun, 02 Aug 2026 07:49:22 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An uninitialized pointer cleanup bug in the i915 execbuffer path can allow a local process with DRM device access to trigger cleanup of bogus `eb.vma` entries, causing at least a kernel crash and requiring manual review for possible memory corruption impact.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2025-71130 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71130

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 7.0
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-2025-71130	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:H/I:H/A:H';CWE-824;*CWE-457;**CWE-476;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'An uninitialized pointer cleanup bug in the i915 execbuffer path can occur when eb_lookup_vmas fails after eb_add_vma has already stored a vma pointer for the current buffer but the following eb.vma entries still contain non zero uninitialized data. eb_release_vmas uses NULL as the stop marker, so cleanup may continue past the valid entries and dereference poison or stale pointer values, causing a kernel crash. For the CVSS the PR:L is used because a local process with access to the i915 DRM render or primary device can submit execbuffer ioctls, which is lower than full administrator privileges in many desktop and GPU compute deployments. The issue is not network reachable and requires local access to the GPU device node. Impact is at least local denial of service via kernel crash. In the paranoid interpretation, traversal of uninitialized kernel pointer values in cleanup is treated as a possible memory corruption candidate, so confidentiality and integrity impact may require manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) 	MAYBE	INIT HARDWARE  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1
  The affected path is `i915_gem_execbuffer2_ioctl()`. A local process with access to the i915 DRM render or primary node can submit execbuffer requests without full root privileges in many deployments.

* Memory corruption, Weak/indirect corruption candidate: +1
  The bug involves uninitialized `eb.vma` entries being interpreted as valid pointers during cleanup. This is not a demonstrated arbitrary write or controlled UAF reclaim primitive, but it is more than simple bookkeeping because cleanup may dereference bogus or stale pointer-like values.

* Reliable kernel crash / strong DoS: +1
  The commit explicitly describes a NULL dereference / slab poison pointer cleanup failure path that can crash the kernel.

* Broad/default/common subsystem exposure: +1
  i915 is a common GPU driver on Intel systems, and DRM render nodes are commonly exposed to local desktop, browser, graphics, container, or GPU-compute workloads.

Conservative total: 4

Paranoid additional signal:

* Weak LPE concern: +1
  The cleanup path operates on object pointers and likely release / put semantics. Although the patch does not show attacker-controlled reclaim, arbitrary write, callback control, or type confusion, the invalid pointer cleanup behavior is enough to justify manual review for possible memory corruption consequences.

Paranoid total: 5

Not counted:

* No remote/network reachability.
* No strong LPE plausibility.
* No strong generic memory corruption primitive.
* No confidentiality or integrity impact in the conservative score.
* No high-control GPU API bonus, because the patch does not demonstrate attacker control over allocator replacement, callback targets, DMA mappings, or a concrete refcount takeover.

## 3. Reachability analysis

The bug is reachable locally through the i915 execbuffer ioctl path. The attacker needs access to the DRM device node, typically `/dev/dri/renderD*` or a primary DRM node, depending on system policy. This is usually less than full administrator privilege and is common on desktop and GPU-enabled systems.

Namespaces and containers may matter if a container or sandbox is granted access to the host DRM render node. In that case, the practical privilege level remains closer to local unprivileged or delegated device access rather than host root.

The path is not network reachable. Realistic triggering requires constructing an execbuffer submission where `eb_add_vma()` or a later lookup/setup step fails after part of `eb.vma` has been populated, causing cleanup to walk uninitialized entries.

Call-site confidence: high, because the patch includes the ioctl allocation path, `eb_lookup_vmas()`, and the cleanup sentinel logic described in the commit.

## 4. Severity interpretation

This behaves above an ordinary Moderate because it is a local DRM ioctl bug involving uninitialized kernel pointer cleanup in a common driver. The realistic demonstrated impact is local denial of service through kernel crash.

Theoretical memory corruption concern exists because bogus `eb.vma` entries can be treated as real cleanup objects, but the patch does not demonstrate a controlled UAF reclaim, arbitrary write, object replacement, callback dispatch, or type confusion. Therefore, the conservative score remains borderline/manual-review level, while the paranoid score reaches Actionable Moderate.

## 5. One-sentence report phrase

An uninitialized pointer cleanup bug in the i915 execbuffer path can allow a local process with DRM device access to trigger cleanup of bogus `eb.vma` entries, causing at least a kernel crash and requiring manual review for possible memory corruption impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

YES REQUIRES MANUAL CHECK because this is a local DRM ioctl issue involving uninitialized kernel pointer values in an object cleanup path, with reliable DoS evidence and a defensible weak memory-corruption concern.

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

Patch: drm/i915/gem: Zero-initialize the eb.vma array in i915_gem_do_execbuffer
Commit: 25d69e07770745992387c016613fd7ac8eaf9893
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25d69e07770745992387c016613fd7ac8eaf9893

Commit description:

Initialize the eb.vma array with values of 0 when the eb structure is
first set up. In particular, this sets the eb->vma[i].vma pointers to
NULL, simplifying cleanup and getting rid of the bug described below.

During the execution of eb_lookup_vmas(), the eb->vma array is
successively filled up with struct eb_vma objects. This process includes
calling eb_add_vma(), which might fail; however, even in the event of
failure, eb->vma[i].vma is set for the currently processed buffer.

If eb_add_vma() fails, eb_lookup_vmas() returns with an error, which
prompts a call to eb_release_vmas() to clean up the mess. Since
eb_lookup_vmas() might fail during processing any (possibly not first)
buffer, eb_release_vmas() checks whether a buffer's vma is NULL to know
at what point did the lookup function fail.

In eb_lookup_vmas(), eb->vma[i].vma is set to NULL if either the helper
function eb_lookup_vma() or eb_validate_vma() fails. eb->vma[i+1].vma is
set to NULL in case i915_gem_object_userptr_submit_init() fails; the
current one needs to be cleaned up by eb_release_vmas() at this point,
so the next one is set. If eb_add_vma() fails, neither the current nor
the next vma is set to NULL, which is a source of a NULL deref bug
described in the issue linked in the Closes tag.

When entering eb_lookup_vmas(), the vma pointers are set to the slab
poison value, instead of NULL. This doesn't matter for the actual
lookup, since it gets overwritten anyway, however the eb_release_vmas()
function only recognizes NULL as the stopping value, hence the pointers
are being set to NULL as they go in case of intermediate failure. This
patch changes the approach to filling them all with NULL at the start
instead, rather than handling that manually during failure.

Reported-by: Gangmin Kim <km.kim1503@gmail.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15062
Fixes: 544460c ("drm/i915: Multi-BB execbuf")
Cc: stable@vger.kernel.org # 5.16.x
Signed-off-by: Krzysztof Niemiec <krzysztof.niemiec@intel.com>
Reviewed-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20251216180900.54294-2-krzysztof.niemiec@intel.com
(cherry picked from commit 08889b7 )
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.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=25d69e07770745992387c016613fd7ac8eaf9893

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

The original Linux kernel CVE announcement for CVE-2025-71130 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-71130

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:L/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: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: 4
  Paranoid ActionableScore: 5

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: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).