[CVE-2026-99006][MODERATE 7.0] drm/i915/gem: Prevent overstepping exec array boundary

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

CVE: CVE-2026-99006
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: drm/i915/gem: Prevent overstepping exec array boundary
Commit: 24c04e80c35ff36947366f6deafddb522eea080c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24c04e80c35ff36947366f6deafddb522eea080c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99006
Analysis date: Mon, 26 Oct 2026 21:06:15 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
An i915 execbuffer cleanup count mismatch reads beyond the relocation array and may pass an unintended pointer to `kvfree()`, causing a crash or conditional invalid free.

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

The original Linux kernel CVE announcement for CVE-2026-99006 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99006

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-2026-99006	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-99006 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-125;CWE-590;CWE-119;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'An original exec array boundary can be overstepped in eb_relocate_parse_slow because eb_parse may append up to two VMAs and increase eb buffer_count after relocation copies were created only for the original exec objects. Error cleanup then reads relocation pointers from entries beyond the original exec array and passes the resulting values to kvfree. This can cause a kernel crash and may create an invalid free or subsequent use after free condition if the out of bounds value refers to a live allocation. For the CVSS the PR:L value is selected because an attacker needs local access to the i915 DRM ioctl path, commonly through a render node, but normally does not need administrative privileges. The issue is not directly network reachable and requires affected i915 hardware plus a command parsing and cleanup path that appends parser VMAs. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 7.8 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage LOW to MODERATE_KPANIC because the ActionableScore threshold rule was applied. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4. The independent weaker Aegis shadow evaluated CVSS 3.3 and ActionableScore 2 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	SIMPLEFIX HARDWARE  KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 4.
* Conservative score: 4; no floor or cap applied.
* Raw paranoid score: 5.
* Paranoid score: 5; no floor or cap applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 — Concrete lifetime-corruption sink: cleanup indexes beyond the original relocation-pointer array and passes the resulting out-of-bounds value to `kvfree()`. This is an unsafe invalid-free primitive, although target control is not shown.
* +1 — Kernel crash/strong DoS is plausible from freeing an invalid address.
* +1 — i915 execbuffer is a materially deployed local ioctl path; the vulnerable branch additionally requires command parsing, appended VMAs, and error cleanup.
* Paranoid +1 — the out-of-bounds slot can be interpreted as a live allocation pointer and freed. This is technically supported by the sink but remains conditional because pointer value/control and a named victim are absent.
* No additional availability point: it would duplicate the same crash.
* No arbitrary write, controlled target, controlled reclaim, disclosure, UAF, LPE, or C/I impact is established.
* NEW52/B5-R does not apply: this is an out-of-bounds read feeding `kvfree()`, not a confirmed retry-accumulated heap OOB write followed by corrupted-state consumption.
* B4-PENDING does not apply; no authorization decision is changed.

3. Reachability analysis

The operation is local and associated with the i915 execbuffer ioctl. The supplied hint grounds likely render-node exposure, but the patch does not establish device-node permissions or prove that a non-admin actor can complete the parser/error sequence. Therefore host-admin and UID-0 requirements remain unknown rather than assumed absent. No namespace capability, prior privileged setup, race, remote path, or unusual hardware beyond affected Intel i915 hardware is shown.

4. Primitive and severity reading

The exact primitive is an out-of-bounds pointer read followed by `kvfree()` on that value. It is cleanup-path lifetime corruption, not a confirmed UAF or direct OOB write. Crash is plausible; freeing a valid adjacent allocation is supported conditionally, while useful target selection and subsequent exploitation are unproven. This is CLASS_B and remains an Important candidate because an attacker-influenced invalid free has unresolved post-free leverage. Automatic downgrade would discard that concrete sink.

5. One-sentence report phrase

An i915 execbuffer cleanup count mismatch reads beyond the relocation array and may pass an unintended pointer to `kvfree()`, causing a crash or conditional invalid free.

6. Manual review advice

MANUAL CHECK REQUIRED

Confirm render-node triggerability, attacker influence over appended-slot contents, and whether a live allocation can be selected and later consumed.

7. Call-site confidence

Call-site confidence: medium

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

Patch: drm/i915/gem: Prevent overstepping exec array boundary
Commit: 24c04e80c35ff36947366f6deafddb522eea080c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24c04e80c35ff36947366f6deafddb522eea080c

Commit description:

It is possible for eb_relocate_parse_slow() to call kvfree() on
entries outside the original exec array during following
scenario inside eb_relocate_parse_slow():

1) eb_copy_relocations() allocates as many as eb->buffer_count
   copies for exec entries;
2) eb_parse() appends up to two VMAs, right after incrementing
   eb->buffer_count;
3) cleanup under "out" label uses this incremented buffer_count
   to release relocation pointers from exec array via kvfree(),
   not from VMA array.

To amend this problem, ensure that relocation cleanup uses the
original exec object count, excluding the VMAs appended by the
command parser.

Fixes: 8e4ba49 ("drm/i915: Parse command buffer earlier in eb_relocate(slow)")
Signed-off-by: Krzysztof Karas <krzysztof.karas@intel.com>
Assisted-by: GitHub-Copilot:gpt-6-astra
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patch.msgid.link/20260911061145.3535489-1-krzysztof.karas@intel.com
(cherry picked from commit 2a01589 )
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=24c04e80c35ff36947366f6deafddb522eea080c

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

The original Linux kernel CVE announcement for CVE-2026-99006 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99006

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 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).