[CVE-2026-64517][MODERATE 7.0] drm/xe/gsc: Fix double-free of managed BO in error path [ Upstream

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

CVE: CVE-2026-64517
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/xe/gsc: Fix double-free of managed BO in error path [ Upstream
Commit: 7cb975fcd4777e7bad688f66aa0c10c16dd8276b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7cb975fcd4777e7bad688f66aa0c10c16dd8276b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64517
Analysis date: Sat, 25 Jul 2026 08:10:57 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A double-free in the drm/xe GSC probe error path can occur when a devm-managed BO is explicitly freed during initialization failure and later released again by devm unwind, causing at least local kernel crash risk and requiring manual review because the bug is a memory lifetime corruption class.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64517 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64517

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-2026-64517	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-415;*CWE-672;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A double-free in the drm/xe GSC probe error path can occur when xe_gsc_init_post_hwconfig explicitly unpins and frees a BO that was allocated by xe_managed_bo_create_pin_map and already registered for devm cleanup. If queue creation or a later initialization step fails during driver initialization, the explicit xe_bo_unpin_map_no_vm call can free the managed BO and devm unwind can later release it again, creating a double-free condition. For the CVSS the PR:L in the paranoid score reflects environments where a reduced capability root, service account, or container with delegated driver or device management can trigger driver probe failure or bind and unbind cycles, while typical host deployments may require PR:H. The issue is not network reachable and requires local control over the affected Intel xe driver initialization path or a failing device or firmware state. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact because double-free is a memory corruption class that should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-64517 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 2e5d47fe7839298fa096970e184aac9bf82c3bd3 YES  NO NO unknown 	MAYBE	DANGER ERRORPATH UAF HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* Generic memory corruption, strong primitive: +2. The patch fixes a real double-free of a managed BO.
* Real lifetime corruption: +1. The object is freed explicitly and then can be released again by devm unwind.
* Reliable kernel crash / strong DoS: +1. Double-free during probe failure can realistically crash the kernel.
* Privileged kernel/device-management memory corruption path: +1. The bug is in drm/xe driver initialization and managed GPU BO lifetime handling.
* Requires admin/root/CAP_* in typical deployments: -2. Reliable triggering normally requires driver probe failure, bind/unbind, device management, or controlled initialization failure.

Paranoid additional/adjusted signals:

* Firmware-mediated external influence: +1. The failing initialization path can depend on device or firmware behavior, even if this is not network reachable.
* Weak LPE concern: +1. Double-free is a memory corruption class, but no attacker-controlled reclaim, overwrite target, or callback control is shown.
* Hard or special trigger condition: -1. The bug is constrained to probe/init error unwinding.
* No attacker-controlled payload or overwrite target shown: -1. The patch does not show controlled replacement or arbitrary write.
* Reduced-privilege device-management interpretation: -1 instead of -2. In some deployments, a service account, container root, or delegated management context may trigger bind/unbind or probe cycles without full host-root equivalence.

## 3. Reachability analysis

The bug is local and not network reachable. In normal deployments, triggering requires influence over the Intel xe driver initialization path, a probe failure, or device/firmware state that makes queue creation fail. Full host administrator privileges are the conservative assumption. A paranoid interpretation treats delegated device management, reduced-capability root, or service accounts with access to driver bind/unbind or device reset paths as PR:L-like practical exposure. Namespaces alone usually do not make this reachable unless device management is explicitly delegated.

Call-site confidence: high. The patch shows the relevant error path, the explicit free, and the removal of the out_bo cleanup path.

## 4. Severity interpretation

This is not an ordinary Low issue because the fixed bug is a real double-free, not only a warning or validation cleanup. Realistic exploitation evidence points mainly to local DoS during driver initialization failure. Theoretical memory corruption impact is higher because double-free can sometimes become exploitable, but this patch does not show attacker-controlled reclaim, object replacement, arbitrary write, or callback control. Therefore the practical result is Actionable Moderate, with manual review justified, but not a strong Important candidate on the provided evidence alone.

## 5. One-sentence report phrase

A double-free in the drm/xe GSC probe error path can occur when a devm-managed BO is explicitly freed during initialization failure and later released again by devm unwind, causing at least local kernel crash risk and requiring manual review because the bug is a memory lifetime corruption class.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the bug is a concrete double-free in a kernel driver lifetime path. Even though the realistic trigger is constrained and likely privileged, memory corruption in probe/error unwinding should not be auto-closed without checking allocator behavior, reachable failure paths, and whether delegated device-management contexts reduce the required privileges.

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UPSTREAM PATCH SUMMARY
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Patch: drm/xe/gsc: Fix double-free of managed BO in error path [ Upstream
Commit: 7cb975fcd4777e7bad688f66aa0c10c16dd8276b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7cb975fcd4777e7bad688f66aa0c10c16dd8276b

Changed files:
  drivers/gpu/drm/xe/xe_gsc.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=7cb975fcd4777e7bad688f66aa0c10c16dd8276b

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

The original Linux kernel CVE announcement for CVE-2026-64517 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64517

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:H/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: 3
  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: NO
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).