[CVE-2026-53371][MODERATE REGULAR] RDMA/ionic: bound node_desc sysfs read with %.64s

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

CVE: CVE-2026-53371
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: RDMA/ionic: bound node_desc sysfs read with %.64s
Commit: 61df14f306f153bffa2f3c74a94ff5a85c99fa39
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61df14f306f153bffa2f3c74a94ff5a85c99fa39
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53371
Analysis date: Sun, 19 Jul 2026 05:58:45 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like, manual review optional but not Important-class
Manual review required: NO

Summary:
An unbounded sysfs string read in RDMA ionic hca_type_show can read past the non NUL terminated 64 byte node_desc field and disclose adjacent kernel structure data to a local actor able to modify the RDMA node_desc attribute.

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

The original Linux kernel CVE announcement for CVE-2026-53371 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53371

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: NO

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-2026-53371	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:L/UI:N/S:U/C:H/I:N/A:N';CWE-126;CWE-125;*CWE-200;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'An unbounded sysfs string read in the RDMA ionic hca_type_show path can read past the fixed 64 byte node_desc field when node_desc is filled without a NUL terminator. A local actor who can modify the RDMA node_desc sysfs attribute can then read hca_type and may receive adjacent kernel structure data until a NUL byte is encountered. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate RDMA device management to a local service account or reduced admin context, while the default sysfs write path is usually root only. The issue is not network reachable and does not provide a direct write primitive. Impact is primarily local information disclosure, with possible leakage of kernel pointers or adjacent metadata that can assist later exploitation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like, manual review optional but not Important-class (with actual score 1)  SKIP CVE-2026-53371 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	SIMPLEFIX NETWORK HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like, manual review optional but not Important-class**::

## 2. Signal breakdown

Conservative signals:

* Confidentiality impact plausible: +1. The unbounded `%s` read can disclose bytes adjacent to `ibdev.node_desc` in `struct ib_device` until a NUL byte is found.
* Requires admin/root/CAP-like control in typical deployments: -2. Writing the `node_desc` sysfs attribute is normally root/admin-controlled through sysfs permissions.
* Rare AND difficult-to-reach subsystem/configuration: -1. This is limited to RDMA ionic hardware/driver exposure, not a broad default kernel path.
* Weak read-only OOB: +0. This is an out-of-bounds read/info leak, not a write, UAF, double-free, refcount issue, or object lifetime corruption.

Paranoid signals:

* Local reduced-privilege trigger concern: +1. Some environments may delegate RDMA device management to service accounts, container-admin-like roles, or automation with less than full host-root authority.
* Confidentiality impact plausible: +1. The overread may expose kernel pointers or adjacent metadata useful for later exploitation.
* No integrity or availability signal: +0. The patch does not show a write primitive, crash, UAF, or privilege escalation path.
* No network reachability: +0. The vulnerable path is local sysfs access, not RDMA packet processing.

## 3. Reachability analysis

The bug is triggered by writing exactly 64 non-NUL bytes into the RDMA `node_desc` sysfs attribute and then reading the ionic `hca_type` sysfs attribute. In typical deployments, modifying sysfs device attributes is restricted to root or an administrative service, so the conservative interpretation is admin-only local reachability. Namespaces or containers could matter only if RDMA device management sysfs access is delegated into a reduced-privilege environment. The affected path also requires ionic RDMA device support, so exposure is hardware and driver dependent.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like information disclosure issue rather than an Important-class kernel vulnerability. The theoretical security concern is kernel memory disclosure from an adjacent-structure overread, potentially including pointers or metadata. The realistic evidence does not show a write primitive, memory lifetime corruption, privilege escalation, crash, callback corruption, or attacker-controlled object replacement. The paranoid score is higher only to account for delegated RDMA management and possible kernel pointer disclosure.

## 5. One-sentence report phrase

An unbounded sysfs string read in RDMA ionic hca_type_show can read past the non NUL terminated 64 byte node_desc field and disclose adjacent kernel structure data to a local actor able to modify the RDMA node_desc attribute.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

This is not an Important-class candidate by itself, but manual review is reasonable because it is a kernel information disclosure and the real risk depends on sysfs permissions, RDMA delegation, and whether adjacent `struct ib_device` fields expose useful kernel pointers or sensitive metadata.

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

Patch: RDMA/ionic: bound node_desc sysfs read with %.64s
Commit: 61df14f306f153bffa2f3c74a94ff5a85c99fa39
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61df14f306f153bffa2f3c74a94ff5a85c99fa39

Commit description:

node_desc[64] in struct ib_device is not guaranteed to be NUL-
terminated. The core IB sysfs handler uses "%.64s" for exactly this
reason (drivers/infiniband/core/sysfs.c:1307), since node_desc_store()
performs a raw memcpy of up to IB_DEVICE_NODE_DESC_MAX bytes with no NUL
termination:

  memcpy(desc.node_desc, buf, min_t(int, count, IB_DEVICE_NODE_DESC_MAX));

If exactly 64 bytes are written via the node_desc sysfs file, the array
contains no NUL byte. The ionic hca_type_show() handler uses unbounded
"%s" and will read past the end of node_desc into adjacent fields of
struct ib_device until it encounters a NUL.

ionic supports IB_DEVICE_MODIFY_NODE_DESC, so this is triggerable by
userspace.

Match the core handler and bound the format specifier.

Cc: stable@vger.kernel.org
Fixes: 2075bbe ("RDMA/ionic: Register device ops for miscellaneous functionality")
Link: https://patch.msgid.link/r/CALynFi7NAbhDCt1tdaDbf6TnLvAqbaHa6-Wqf6OkzREbA_PAfg@mail.gmail.com
Signed-off-by: Kai Aizen <kai.aizen.dev@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/infiniband/core/sysfs.c
  drivers/infiniband/hw/ionic/ionic_ibdev.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=61df14f306f153bffa2f3c74a94ff5a85c99fa39

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

The original Linux kernel CVE announcement for CVE-2026-53371 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53371

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: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: 0
  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).