[CVE-2026-72501][MODERATE REGULAR] RDMA/bnxt_re: Initialize dpi variable to zero

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

CVE: CVE-2026-72501
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: RDMA/bnxt_re: Initialize dpi variable to zero
Commit: b87cbd4d198ae377be4815d8102fa9dfefb91dcc
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b87cbd4d198ae377be4815d8102fa9dfefb91dcc
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72501
Analysis date: Sun, 16 Aug 2026 05:40:58 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like with manual review recommended
Manual review required: YES

Summary:
An uninitialized `dpi` stack value in the `bnxt_re` RDMA uverbs allocation path may be copied to userspace, causing a local information disclosure for users with access to the affected RDMA device.

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

The original Linux kernel CVE announcement for CVE-2026-72501 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72501

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.

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

CVE-2026-72501	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N';*CWE-457;*CWE-200;CWE-908;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'An uninitialized u32 dpi stack variable in the bnxt_re RDMA UAPI allocation path may be copied back to userspace for allocation types where dpi was never set. This is a local information disclosure issue through the uverbs control interface rather than a remotely reachable RDMA packet path. For the CVSS the PR:L is used because an attacker needs local access to the RDMA uverbs device or equivalent permissions to issue the bnxt_re allocation method. Impact is primarily confidentiality loss from leaking a small uninitialized kernel stack value. For the paranoid score, the highest still defensible interpretation is C:H because repeated UAPI calls may expose kernel stack data, but I:N and A:N remain because the patch does not indicate memory corruption or control flow impact.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like with manual review recommended (with actual score 2)  SKIP CVE-2026-72501 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	READ SIMPLEFIX NETWORK 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like with manual review recommended**

## 2. Signal breakdown

Conservative signals:

* Confidentiality impact plausible: +1
  The uninitialized `u32 dpi` stack variable may be copied back to userspace through the RDMA uverbs UAPI response.
* Rare AND difficult-to-reach subsystem/configuration: -1
  This is specific to the `bnxt_re` RDMA driver and requires a system with the relevant Broadcom RDMA hardware and exposed uverbs device.
* Local low-privileged trigger in applicable deployments: +1
  If a local user has access to the RDMA uverbs device node, the allocation method can plausibly be invoked without full host-root privileges.

Paranoid delta:

* Do not subtract rarity in an affected deployment: +1 relative to conservative
  On systems actually using `bnxt_re`, the affected UAPI path is direct once uverbs access is available.

Not awarded:

* No remote/network-triggerable signal. This is a local uverbs control path, not an RDMA packet parsing path.
* No generic memory corruption signal. The patch only initializes a scalar stack variable before it is copied out.
* No privilege escalation signal. There is no UAF, OOB write, type confusion, refcount misuse, callback control, or write primitive.
* No RDMA high-control API bonus. The patch does not show attacker control over object lifetime, DMA ownership, callbacks, refcounts, or kernel memory layout.

## 3. Reachability analysis

A local process with access to the `bnxt_re` RDMA uverbs interface can potentially trigger the issue by invoking the affected page allocation method for allocation types where `dpi` was not initialized. This is not realistically reachable over the network by ordinary RDMA traffic. Namespace and container impact depends on whether the RDMA device node is delegated into the container. If the device is exposed to a container or service account, this should be treated as PR:L rather than PR:H. The path is not default-exposed on systems without the relevant Broadcom RDMA hardware and driver.

Call-site confidence: medium. The commit message explicitly says `dpi` is copied for all cases, but the provided diff does not include the full response-copying code.

## 4. Severity interpretation

This behaves like a local information disclosure issue, not an Important-class memory corruption bug. The realistic impact is leakage of a small uninitialized kernel stack value through a device UAPI response. The paranoid interpretation can treat repeated calls as potentially exposing more useful kernel stack data, but the patch does not support integrity impact, availability impact, or privilege escalation.

## 5. One-sentence report phrase

An uninitialized `dpi` stack value in the `bnxt_re` RDMA uverbs allocation path may be copied to userspace, causing a local information disclosure for users with access to the affected RDMA device.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Kernel stack disclosures through UAPI responses can be security-relevant even when the leaked value is small, but this does not currently rise to an Actionable Moderate or Important candidate without evidence of broader disclosure or exploit chaining.

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

Patch: RDMA/bnxt_re: Initialize dpi variable to zero
Commit: b87cbd4d198ae377be4815d8102fa9dfefb91dcc
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b87cbd4d198ae377be4815d8102fa9dfefb91dcc

Commit description:

dpi is initialized only for BNXT_RE_ALLOC_WC_PAGE, but copied
for all the cases. So initialize the dpi to 0.

Fixes: eee6268 ("RDMA/bnxt_re: Move the UAPI methods to a dedicated file")
Fixes: 360da60 ("RDMA/bnxt_re: Enable low latency push")
Link: https://patch.msgid.link/r/20260615224751.232802-2-selvin.xavier@broadcom.com
Reviewed-by: Anantha Prabhu <anantha.prabhu@broadcom.com>
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/infiniband/hw/bnxt_re/uapi.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=b87cbd4d198ae377be4815d8102fa9dfefb91dcc

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

The original Linux kernel CVE announcement for CVE-2026-72501 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72501

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:L/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
  The Best / paranoid CVSS score: 5.5

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: 1
  Paranoid ActionableScore: 2

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).