[CVE-2026-72064][MODERATE REGULAR] net: mana: Sync page pool RX frags for CPU

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

CVE: CVE-2026-72064
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net: mana: Sync page pool RX frags for CPU
Commit: bc650dd5ce6434286b96e2b26a41af81f679cc7c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bc650dd5ce6434286b96e2b26a41af81f679cc7c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72064
Analysis date: Sat, 15 Aug 2026 21:37:28 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended / Ordinary Moderate otherwise
Manual review required: YES

Summary:
A missing sync-for-CPU operation for MANA page pool RX fragments can allow remote traffic to cause stale or corrupted packet data to be processed on DMA configurations requiring explicit synchronization, leading primarily to RX failure or denial of service.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72064 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72064

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 REGULAR
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-2026-72064	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-662;*CWE-664;CWE-755;Other CVSS 'AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.9';DESCR 'MANA RX buffers allocated as page pool fragments can remain DMA mapped and skip the implicit sync for CPU that normally happens through dma_unmap_single. On systems that require explicit DMA synchronization, such as swiotlb forced configurations or DMA incoherent paths, packet bytes may be read by the CPU before the received range is synchronized. A remote peer can trigger the affected RX path by sending traffic to the MANA interface, but reliable impact depends on platform DMA behavior and whether page pool RX fragments are used. For the CVSS the PR:N because no local account is needed if the attacker can reach the network interface. Impact is primarily denial of service or broken RX behavior through stale or corrupted packet data, with no clear UAF, OOB write, or privilege escalation primitive shown by the code change.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / Ordinary Moderate otherwise (with actual score 3)	YES	REMOTE NETWORK DMAorINTERRUPT HARDWARE MEMORY PACKET  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / Ordinary Moderate otherwise**::

## 2. Signal breakdown

Conservative signals:

* Remote reachable / network-triggerable: +2. A remote peer can exercise the RX path by sending traffic to the affected MANA interface.
* Availability impact realistic: +1. On systems requiring explicit DMA sync, RX can break or process stale/corrupted packet bytes.
* Rare AND difficult-to-reach subsystem/configuration: -1. The practical failure depends on MANA, page pool RX fragments, frag_count greater than 1, and DMA configurations such as swiotlb=force or incoherent DMA behavior.

Paranoid additional interpretation:

* Reliable kernel crash / strong DoS: +1 can be considered only as a paranoid availability signal if RX corruption makes the interface effectively unusable under sustained traffic. This is not supported as memory corruption or LPE.

Not awarded:

* No generic memory corruption. The patch fixes DMA coherency/sync, not UAF, double free, OOB write, type confusion, or arbitrary write.
* No privilege escalation plausible. There is no reclaim, overwrite, callback, object confusion, or refcount takeover primitive.
* No confidentiality or integrity impact. The patch supports stale or unsynchronized RX data, not a demonstrated information leak or attacker-controlled kernel write.

## 3. Reachability analysis

A remote sender can trigger RX processing by sending packets to a reachable MANA interface, so PR:N is reasonable for network reachability. The issue is not in a common networking core path, but in the Microsoft MANA NIC driver. Exploitation depends on affected deployment details, especially page pool fragment use and a platform or boot configuration that requires explicit DMA synchronization. Namespaces do not materially reduce the privilege requirement because the trigger is packet reception, not a local control-plane API.

Call-site confidence: high. The patch includes allocation, refill, RX completion, and the newly stored page pool sync metadata.

## 4. Severity interpretation

This behaves like an ordinary Moderate to borderline actionable Moderate issue. The realistic impact is availability degradation or broken RX behavior on specific MANA DMA configurations. The theoretical concern is that stale or corrupted packet data enters the networking stack, but the patch does not show a concrete memory corruption primitive, kernel crash path, data disclosure primitive, or privilege escalation path.

## 5. One-sentence report phrase

A missing sync-for-CPU operation for MANA page pool RX fragments can allow remote traffic to cause stale or corrupted packet data to be processed on DMA configurations requiring explicit synchronization, leading primarily to RX failure or denial of service.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: network-triggerable RX-path bugs should not be auto-closed without checking product exposure, but the current patch supports availability impact only and does not justify Important-class handling.

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

Patch: net: mana: Sync page pool RX frags for CPU
Commit: bc650dd5ce6434286b96e2b26a41af81f679cc7c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bc650dd5ce6434286b96e2b26a41af81f679cc7c

Commit description:

MANA allocates RX buffers from page pool fragments when frag_count is
greater than 1. In that case the buffers remain DMA mapped by page pool
and the RX completion path does not call dma_unmap_single(). As a result,
the implicit sync-for-CPU normally performed by dma_unmap_single() is
missing before the packet data is passed to the networking stack.

This breaks RX on configurations which require explicit DMA syncing, for
example when booted with swiotlb=force.

Fix this by recording the page pool page and DMA sync offset when the RX
buffer is allocated, and syncing the received packet range for CPU access
before handing the RX buffer to the stack.

Fixes: 730ff06 ("net: mana: Use page pool fragments for RX buffers instead of full pages to improve memory efficiency.")
Cc: stable@vger.kernel.org
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Link: https://patch.msgid.link/20260702041237.617719-3-decui@microsoft.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/microsoft/mana/mana_en.c
  include/net/mana/mana.h

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=bc650dd5ce6434286b96e2b26a41af81f679cc7c

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

The original Linux kernel CVE announcement for CVE-2026-72064 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72064

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:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.9

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: 2
  Paranoid ActionableScore: 3

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 REGULAR

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).