[CVE-2026-72274][LOW] fbdev: hecubafb: fix potential memory leak in hecubafb_probe()

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

CVE: CVE-2026-72274
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: fbdev: hecubafb: fix potential memory leak in hecubafb_probe()
Commit: 3eb2bc1009c2476426ffbaf642d7ac82f4685b4d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3eb2bc1009c2476426ffbaf642d7ac82f4685b4d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72274
Analysis date: Sat, 15 Aug 2026 08:30:48 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A probe error path in `hecubafb` can leak deferred-I/O pagerefs memory after `fb_deferred_io_init()` succeeds and `register_framebuffer()` fails, but exploitation requires privileged driver or device-management control and has DoS-only resource exhaustion impact.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72274 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72274

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: LOW
Manual review required: NO

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-2026-72274	LOW	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:H/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'A memory leak in hecubafb_probe() can occur when fb_deferred_io_init() succeeds but a later register_framebuffer() call fails on the probe error path. The pagerefs memory allocated for deferred I/O is then not released, so repeated failed probe attempts could gradually consume kernel memory. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over driver probing, module loading, platform device binding, or a controlled hardware setup. The issue is not network reachable and does not provide an evident read, write, UAF, or OOB primitive. Impact is denial of service only through resource exhaustion, and practical risk is low because the leak is limited to an uncommon fbdev driver and an error path.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0)  SKIP CVE-2026-72274 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	INIT LEAK ERRORPATH UAF LINUS 	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Triggered signals:

* Availability impact realistic: +1
  Repeated failed probe attempts could gradually leak pagerefs memory and eventually contribute to resource exhaustion.

Subtracting signals:

* Requires admin/root/device-management control in typical deployments: -2
  Reliable triggering normally requires control over module loading, platform-device binding, driver probing, or a controlled hardware setup.
* Rare AND difficult-to-reach subsystem/configuration: -1
  hecubafb is an uncommon fbdev driver path and the leak is only on a probe error path.

Not triggered:

* No remote reachability.
* No local unprivileged trigger shown.
* No UAF, double free, OOB write, arbitrary write, type confusion, or page-cache corruption.
* No plausible privilege escalation primitive.
* No confidentiality or integrity impact.

Raw score is negative after penalties, clamped to 0.

## 3. Reachability analysis

The bug is reachable only if `hecubafb_probe()` runs, `fb_deferred_io_init()` succeeds, and a later `register_framebuffer()` error path is taken. This is a local privileged device/driver initialization scenario. Namespaces or containers do not normally lower the requirement because probing and binding this platform framebuffer driver is host-admin controlled. The path is not network reachable and is not a default broad attack surface.

Call-site confidence: high. The relevant init and error-unwind path is visible in the patch.

## 4. Severity interpretation

This behaves like a Low-like or ordinary Moderate resource leak, not an Important-class kernel vulnerability. The realistic impact is gradual memory consumption after repeated privileged failed probe attempts. There is no demonstrated memory corruption, no sensitive-object access, no ownership bypass, and no LPE evidence.

## 5. One-sentence report phrase

A probe error path in `hecubafb` can leak deferred-I/O pagerefs memory after `fb_deferred_io_init()` succeeds and `register_framebuffer()` fails, but exploitation requires privileged driver or device-management control and has DoS-only resource exhaustion impact.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a privileged, rare-driver, error-path memory leak without memory corruption or security-boundary bypass, so it can be auto-closed or deferred in normal triage.

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UPSTREAM PATCH SUMMARY
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Patch: fbdev: hecubafb: fix potential memory leak in hecubafb_probe()
Commit: 3eb2bc1009c2476426ffbaf642d7ac82f4685b4d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3eb2bc1009c2476426ffbaf642d7ac82f4685b4d

Commit description:

The memory allocated for pagerefs in fb_deferred_io_init() is not freed
on the error path. Fix it by calling fb_deferred_io_cleanup().

Fixes: 56c134f ("fbdev: Track deferred-I/O pages in pageref struct")
Cc: stable@vger.kernel.org
Signed-off-by: Abdun Nihaal <nihaal@cse.iitm.ac.in>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/video/fbdev/hecubafb.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=3eb2bc1009c2476426ffbaf642d7ac82f4685b4d

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

The original Linux kernel CVE announcement for CVE-2026-72274 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72274

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.1

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: unknown
  Paranoid ActionableScore: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).