[CVE-2026-97573][MODERATE 7.0] bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()

[CVE-2026-97573][MODERATE 7.0] bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()

[AL-KERNEL]

CVE: CVE-2026-97573
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
Commit: 1a3670b6a6b5679fe56c5890157b344f091e64f8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1a3670b6a6b5679fe56c5890157b344f091e64f8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97573
Analysis date: Tue, 29 Sep 2026 00:50:13 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97573 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97573

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-2026-97573	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97573 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';CWE-252;CWE-703;CWE-665;*CWE-787;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.5';DESCR 'An allocation failure in bnxt_rx_ring_reset() can leave part of the RX TPA array uninitialized while TPA processing is enabled again. A later hardware agg_id can select an empty slot and expose DMA address 0 to the NIC. With an IOMMU this is most likely to cause a DMA fault, interface failure, or system denial of service. Without effective DMA isolation, the device may write received data to an unintended low physical address and potentially corrupt kernel memory. Triggering requires a rare combination of an RX ring reset, memory allocation failure, and subsequent TPA packet processing, so attack complexity is high. For the CVSS the PR:N value in the paranoid score reflects an adjacent attacker who can supply network traffic after the vulnerable partial allocation state has occurred without requiring an account on the target. Potential privilege escalation is not proven, but the possible device DMA write makes confidentiality and integrity impact plausible enough to require manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) 	MAYBE	REMOTE OOB NETWORK DMAorINTERRUPT HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 5
* Paranoid score: 5
* No floor or cap was applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Conservative signals:

* +1 Constrained kernel overwrite candidate. A failed TPA allocation leaves zeroed entries that can supply DMA address 0 to the NIC. The destination is fixed and no arbitrary target selection is established.
* +1 Privileged kernel or device-management memory corruption path. The invalid value becomes an active hardware DMA destination rather than passive bookkeeping.
* +1 Firmware or device-mediated external influence. Hardware selects the affected slot through agg_id, and subsequent RX processing can activate it.
* +1 Memory-layout and ring-state invariant violation. TPA is re-enabled despite only partial allocation of the array used to derive DMA destinations.
* Total: 4.

Additional paranoid signal:

* +1 Weak exploitation concern. If DMA address 0 is usable without effective IOMMU isolation, network-derived data may be written to unintended low physical memory. This remains constrained because the destination is fixed.
* Total: 5.

Material signals not awarded:

* No +2 direct remote reachability because traffic alone is not shown to force the prerequisite RX-ring reset and ENOMEM failure.
* No local-unprivileged bonus because one actor is not shown to control the complete trigger sequence.
* No reliable host-crash point because the supplied evidence establishes an invalid DMA destination, not a demonstrated host panic. An IOMMU fault or device recovery may limit the effect.
* No strong corruption or LPE bonus because target selection, controlled reclaim, arbitrary write, credential corruption, and privilege escalation are not demonstrated.
* No confidentiality or integrity bonus because modification of a specific protected object and any disclosure path are not established.
* No hardware rarity penalty because the affected Broadcom NIC requirement is concrete, but the hardware is not established as rare or physical-only.
* No timing penalty because this is an ordered allocation-failure path, not a demonstrated hard race.
* RealUAF is NO. There is no release followed by post-lifetime object use or repeated refcount mutation.

3. Reachability analysis

The complete trigger requires an RX-ring reset, failure inside `bnxt_alloc_one_tpa_info_data()`, continued operation with a partially initialized TPA array, and later hardware selection of an empty slot. A network peer may influence the final RX workload, but the evidence does not show that traffic can reliably force both the reset and allocation failure.

Host-admin privilege is not positively required by the shown path because the reset may be initiated internally after buffer errors. Below-host-admin control of the complete sequence is also not established, so `HostAdminRequired=UNKNOWN`.

The vulnerable state belongs to a physical NIC and its host driver. No complete user-namespace or network-namespace trigger is demonstrated, so `NamespaceScopedPrivilege=UNKNOWN`. The Broadcom bnxt device and TPA or aggregation support are prerequisites. This is not a race, and repeated attempts may be possible under memory pressure, but attacker control over ENOMEM is unresolved.

4. Primitive and severity interpretation

The exact primitive is activation of an incompletely allocated RX TPA state followed by exposure of DMA address 0 to the NIC. This is active DMA descriptor corruption, not a UAF, stale-storage access, or repeated lifetime mutation.

With effective IOMMU protection, the likely outcome is a DMA fault, failed RX processing, device reset, or availability degradation. Without effective isolation, the NIC may write received data to unintended low physical memory. That is a concrete enough corruption candidate for `CLASS_B`, but it remains constrained because the address is fixed and the patch does not establish arbitrary destination selection or modification of a security-sensitive object.

The theoretical worst case includes host-memory corruption and possible exploitation beyond DoS. Patch-supported practical evidence establishes only the invalid DMA destination and the conditions leading to it. `ImportantCandidate=YES` and `AutoDowngradeAllowed=NO` are appropriate because automatically treating the issue as an ordinary allocation failure could discard an unresolved hardware DMA corruption path. It is not `CLASS_A` without evidence of a usable mapping at address 0, attacker-controlled DMA extent, directed corruption, or a practical escalation chain.

5. One-sentence report phrase

A failed bnxt RX TPA allocation can leave active zeroed slots that expose DMA address 0 to the NIC, creating a device failure or constrained host memory corruption risk that requires IOMMU and DMA mapping review.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Confirm whether DMA address 0 is rejected by the IOMMU on affected deployments, whether it can reference host physical memory without isolation, how much received data the NIC can write, and whether an unprivileged or adjacent attacker can induce the reset and allocation-failure sequence.

7. Call-site confidence

Call-site confidence: medium

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

Patch: bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
Commit: 1a3670b6a6b5679fe56c5890157b344f091e64f8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1a3670b6a6b5679fe56c5890157b344f091e64f8

Commit description:

bnxt_rx_ring_reset() frees the ring buffers and then reallocates them,
ignoring the result.

bnxt_alloc_one_rx_ring() can fail in bnxt_alloc_one_tpa_info_data(), which
returns -ENOMEM on the first failed allocation and leaves the remaining
rxr->rx_tpa[] entries zeroed.

The error isn't propagated up, so the loop in bnxt_rx_ring_reset
continues and at the end the code re-enables TPA with partially
unallocated rx_tpa array.

This means that when the agg_id from hardware is mapped to a SW index in
rxr->rx_tpa[], an uninitialized slot can be chosen which would hand a
zero DMA address to the device.

Fix this by falling back to a global reset, which is what the existing
code already does when other functions fail, but unlike the other
failure cases this particular failure has to return because TPA can't
be re-enabled since the allocation failed.

Fixes: 8fbf58e ("bnxt_en: Implement RX ring reset in response to buffer errors.")
Reported-by: Sashiko <sashiko-bot+sashiko@kernel.org>
Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260828190900.1767611-1-joe%40dama.to
Cc: stable@vger.kernel.org
Signed-off-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20260902015652.2421609-5-joe@dama.to
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/broadcom/bnxt/bnxt.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=1a3670b6a6b5679fe56c5890157b344f091e64f8

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

The original Linux kernel CVE announcement for CVE-2026-97573 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97573

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:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.5

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: 4
  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: 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).