[CVE-2026-64110][LOW] igc: fix potential skb leak in igc_fpe_xmit_smd_frame()

[CVE-2026-64110][LOW] igc: fix potential skb leak in igc_fpe_xmit_smd_frame()

[AL-KERNEL]

CVE: CVE-2026-64110
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: igc: fix potential skb leak in igc_fpe_xmit_smd_frame()
Commit: f1bafd35f11b3aca1c7bb38da173b8787364a04c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f1bafd35f11b3aca1c7bb38da173b8787364a04c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64110
Analysis date: Sun, 19 Jul 2026 21:09:29 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An skb leak in igc_fpe_xmit_smd_frame() can occur when FPE verification descriptor initialization fails, causing local privileged resource exhaustion risk on affected igc devices, but no memory corruption or privilege escalation primitive is evident.

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

The original Linux kernel CVE announcement for CVE-2026-64110 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64110

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.

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

CVE-2026-64110	LOW	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A memory leak in igc_fpe_xmit_smd_frame() can occur when an skb is allocated for a frame preemption verification SMD frame and igc_fpe_init_tx_descriptor() fails before ownership is transferred to the TX path. Repeated failures can leak skb objects and may eventually cause resource exhaustion or network driver degradation. For the CVSS the PR:L is used in the paranoid view because a reduced capability administrator, container root, or service account with delegated network device control could potentially enable or exercise the MAC Merge verification path. The issue is not directly network reachable and requires local control of the affected interface configuration plus a failing descriptor initialization path. Impact is denial of service through memory leakage only, with no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	REMOTE INIT SIMPLEFIX LEAK ERRORPATH NETWORK SKB  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Conservative signals:

* Availability impact realistic: +1
  Repeated skb leaks could eventually cause memory pressure or driver degradation.
* Requires admin/root/CAP_NET_ADMIN in typical deployments: -2
  The trigger path is via MAC Merge / FPE configuration, typically controlled through ethtool and requiring CAP_NET_ADMIN.
* Rare AND difficult-to-reach subsystem/configuration: -1
  Requires an affected Intel igc device, FPE/MM support, verification enabled, and the descriptor initialization failure path.
* Hard or unreliable trigger condition: -1
  The reproducer used fault injection to force igc_fpe_init_tx_descriptor() failure.

Paranoid adjustment:

* Treat repeated delegated network-device control as a possible sustained resource-exhaustion path. This raises practical concern slightly, but still not to Actionable Moderate.

No added signals:

* No memory corruption primitive. This is an skb leak, not UAF, double-free, OOB write, or type confusion.
* No privilege escalation plausible from the patch.
* No remote/network-triggerable path. Packet traffic alone does not appear to reach the failing allocation ownership path.
* No confidentiality or integrity impact.

Call-site confidence: high. The relevant caller chain is shown in the commit message and the patched function directly frees the leaked skb on the error path.

## 3. Reachability analysis

The bug is reachable through the igc Frame Preemption / MAC Merge verification path, with the shown trigger using ethtool configuration. In normal deployments this requires local administrative network-device control, usually CAP_NET_ADMIN. A container or service with delegated control over the physical interface could lower the practical privilege barrier, but this is still not a normal unprivileged local trigger.

The affected path is hardware and feature dependent. It requires an Intel igc adapter with the relevant FPE/MM support and a failure in igc_fpe_init_tx_descriptor(). The commit explicitly mentions fault injection to exercise the error path, so reliable real-world triggering is not demonstrated.

## 4. Severity interpretation

This behaves like a low-end Moderate or Low-like resource leak. The realistic impact is memory consumption or network-driver degradation after repeated failures. It does not look like an Important-class kernel vulnerability because the patch does not show memory corruption, object lifetime reuse, attacker-controlled reclaim, arbitrary write, page-cache corruption, sensitive object access, or a security-boundary bypass.

The paranoid score stays low because even assuming delegated CAP_NET_ADMIN and repeated triggering, the impact remains DoS by leak only.

## 5. One-sentence report phrase

An skb leak in igc_fpe_xmit_smd_frame() can occur when FPE verification descriptor initialization fails, causing local privileged resource exhaustion risk on affected igc devices, but no memory corruption or privilege escalation primitive is evident.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent triage purposes because it is a privileged, hardware/feature-dependent skb leak with no evidence of memory corruption, remote reachability, confidentiality impact, integrity impact, or privilege escalation.

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

Patch: igc: fix potential skb leak in igc_fpe_xmit_smd_frame()
Commit: f1bafd35f11b3aca1c7bb38da173b8787364a04c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f1bafd35f11b3aca1c7bb38da173b8787364a04c

Commit description:

When igc_fpe_init_tx_descriptor() fails, no one takes care of an
allocated skb, leaking it. [1]
Use dev_kfree_skb_any() on failure.

Tested on an I226 adapter with the following command, while injecting
faults in igc_fpe_init_tx_descriptor() to trigger the error path.
 # ethtool --set-mm $DEV verify-enabled on tx-enabled on pmac-enabled on

[1]
unreferenced object 0xffff888113c6cdc0 (size 224):
...
  backtrace (crc be3d3fda):
    kmem_cache_alloc_node_noprof+0x3b1/0x410
    __alloc_skb+0xde/0x830
    igc_fpe_xmit_smd_frame.isra.0+0xad/0x1b0
    igc_fpe_send_mpacket+0x37/0x90
    ethtool_mmsv_verify_timer+0x15e/0x300

Cc: stable@vger.kernel.org
Fixes: 5422570 ("igc: add support for frame preemption verification")
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Tested-by: Avigail Dahan <avigailx.dahan@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20260515182419.1597859-10-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/intel/igc/igc_tsn.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=f1bafd35f11b3aca1c7bb38da173b8787364a04c

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

The original Linux kernel CVE announcement for CVE-2026-64110 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64110

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:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 1

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).