[CVE-2026-74452][MODERATE 7.0] drm/panthor: reject firmware sections with oversized data

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

CVE: CVE-2026-74452
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: drm/panthor: reject firmware sections with oversized data
Commit: 0e57165ca025a67d8dfd17efd2765fdd4925fdab
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e57165ca025a67d8dfd17efd2765fdd4925fdab
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74452
Analysis date: Sat, 15 Aug 2026 13:32:26 -0400
ActionableScore: 6
ActionableScore lower bound: 5
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A crafted Panthor firmware section can declare data larger than the allocated section size, causing a kernel heap buffer overflow or oversized out-of-bounds memset during firmware section initialization, with realistic impact of local DoS and worst-case kernel memory corruption if firmware delivery is attacker-influenced.

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

The original Linux kernel CVE announcement for CVE-2026-74452 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74452

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-74452	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-122;*CWE-20;CWE-191;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.7';DESCR 'A crafted Panthor firmware section can declare initial data that is larger than the allocated section size. This can make panthor_fw_init_section_mem copy too much data into the kernel mapped buffer and may also make the following zero fill length underflow, causing an oversized out of bounds memset. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over the firmware file or the firmware loading path. The issue is not network reachable and is triggered during local firmware loading for the GPU driver. Impact is at least local denial of service via kernel memory corruption and in the worst case may allow confidentiality or integrity impact if the overflow can be shaped reliably.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 7)  SKIP CVE-2026-74452 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	WRITE OOB SIMPLEFIX HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN6 DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=6
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 6
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1
  The attacker-controlled input is a crafted Panthor firmware image or firmware section metadata, not ordinary network traffic.

* Memory corruption, Strong corruption primitive: +2
  The patch prevents data_size from exceeding section_size. Without the check, memcpy() can copy past the allocated section buffer, and memset() length calculation can underflow into a large out-of-bounds zeroing operation.

* Privileged kernel/device-management memory corruption path: +1
  The corruption occurs in a GPU driver firmware-loading path, which is a trusted kernel/device-management context.

* Reliable kernel crash / strong DoS: +1
  A heap buffer overflow or oversized out-of-bounds memset is highly likely to cause a kernel crash or serious kernel memory corruption.

* Integrity impact plausible: +1
  The bug provides an out-of-bounds write primitive in kernel memory, so integrity impact is plausible.

* Confidentiality impact plausible: +1
  Confidentiality impact is less direct than integrity impact, but kernel heap corruption can plausibly affect sensitive kernel state in worst cases.

* Requires admin/root/CAP_* in typical deployments: -2
  Reliable triggering normally requires control over the firmware blob or firmware loading path, which is typically restricted to root or system update mechanisms.

Conservative total: 5

Paranoid additional signal:

* Weak LPE concern: +1
  Although normal triggering is PR:H, the primitive is kernel heap/OOB write from crafted firmware-controlled metadata and should be treated as potentially exploitable if firmware delivery or update control is delegated, compromised, or otherwise attacker-influenced.

Paranoid total: 6

## 3. Reachability analysis

This is not network reachable in the normal sense. The realistic trigger is local or firmware-mediated: a crafted Panthor firmware section must be supplied to the driver during firmware loading. In typical deployments, firmware files and the firmware loading path are controlled by root or by a privileged update mechanism, so the conservative privilege interpretation is admin/root required.

Namespaces or containers usually do not make this directly reachable, because container users normally cannot replace host GPU firmware or force arbitrary host firmware loading. However, the risk increases in systems where firmware update, device provisioning, vendor blobs, or initramfs contents can be influenced by a reduced-privilege service or supply-chain path.

Call-site confidence: medium-high. The supplied text gives the relevant downstream copy and memset sinks in panthor_fw_init_section_mem(), even though the full caller body is not included.

## 4. Severity interpretation

This behaves above ordinary Moderate because the patch addresses a concrete kernel memory corruption primitive, not just validation cleanup or a warning. Realistic exploitation is constrained by firmware control requirements, so it is not a straightforward local unprivileged LPE. The conservative handling is Actionable Moderate because PR:H limits practical exposure, but the OOB write and memset underflow make it unsuitable for auto-close. The paranoid interpretation reaches the upper Actionable Moderate range because crafted firmware metadata can influence a kernel heap overwrite in a privileged driver path.

## 5. One-sentence report phrase

A crafted Panthor firmware section can declare data larger than the allocated section size, causing a kernel heap buffer overflow or oversized out-of-bounds memset during firmware section initialization, with realistic impact of local DoS and worst-case kernel memory corruption if firmware delivery is attacker-influenced.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a concrete kernel OOB write / heap overflow candidate in a firmware-fed GPU driver path. Even though typical triggering requires privileged firmware control, the memory corruption primitive is strong enough that the issue should not be auto-closed.

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

Patch: drm/panthor: reject firmware sections with oversized data
Commit: 0e57165ca025a67d8dfd17efd2765fdd4925fdab
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e57165ca025a67d8dfd17efd2765fdd4925fdab

Commit description:

In panthor_fw_load_section_entry(), the data size to copy is calculated
without validating it against the allocated section_size:

    section->data.size = hdr.data.end - hdr.data.start;

If a crafted firmware sets data.size larger than the allocated memory,
this could cause a heap buffer overflow in panthor_fw_init_section_mem()

    memcpy(section->mem->kmap, section->data.buf, section->data.size);

Additionally, if the section->data.size exceeds the BO size, could this
memset underflow the size calculation, leading to a massive out-of-bounds
zeroing of kernel memory?

    memset(section->mem->kmap + section->data.size, 0,
           panthor_kernel_bo_size(section->mem) - section->data.size);

Reject section entries whose initial data is larger than the section size.

Fixes: 2718d91 ("drm/panthor: Add the FW logical block")
Cc: stable@vger.kernel.org
Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patch.msgid.link/20260716143939.21903-1-osama.abdelkader@gmail.com
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/panthor/panthor_fw.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=0e57165ca025a67d8dfd17efd2765fdd4925fdab

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

The original Linux kernel CVE announcement for CVE-2026-74452 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74452

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:H/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.7

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: 5
  Paranoid ActionableScore: 6

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).