[CVE-2026-46145][IMPORTANT] RDMA/mana: Validate rx_hash_key_len [ Upstream

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

CVE: CVE-2026-46145
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: RDMA/mana: Validate rx_hash_key_len [ Upstream
Commit: 7d7c9f0fcd19c4d2f0164347c58d49cafa961b72
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d7c9f0fcd19c4d2f0164347c58d49cafa961b72
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46145
Analysis date: Thu, 28 May 2026 12:41:15 -0400
ActionableScore: 9
ActionableScore lower bound: 8
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A userspace controlled `rx_hash_key_len` in RDMA/mana was used as a `memcpy()` length without bounds checking, allowing a local process with RDMA uverbs access to overflow a kernel buffer and potentially crash the kernel or escalate privileges.

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

The original Linux kernel CVE announcement for CVE-2026-46145 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46145

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: IMPORTANT
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-2026-46145	IMPORTANT	CHECK	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:H/A:H';*CWE-787;CWE-120;*CWE-20;BEST CVSS score: '7.8';DESCR 'A kernel memory corruption issue exists in RDMA/mana because rx_hash_key_len is supplied from a userspace uAPI structure and was used as a memcpy length without validating it against the size of the destination hash key buffer. A local userspace process with access to the RDMA mana uverbs path could provide an oversized length and overwrite adjacent kernel memory, which can cause a kernel crash and may provide a path to privilege escalation depending on allocator layout and overwrite control. For the CVSS the PR:L is used because triggering requires local code execution and access to the RDMA userspace interface, but it does not require full administrator privileges in typical RDMA enabled deployments. The issue is not directly network reachable as a packet processing bug. Impact is kernel memory corruption with high availability impact and plausible confidentiality and integrity impact, so manual review is required.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 9) 	MAYBE	OOB SIMPLEFIX NETWORK KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS	-	-	guess

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

ActionableScore=9
ActionableScoreLower=8

## 1. ActionableScore

* Conservative score: **8**
* Paranoid score: **9**
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**

## 2. Signal breakdown

* Local unprivileged trigger: **+1**. The input comes from a userspace uAPI path, likely via RDMA uverbs access to the MANA device.
* Strong memory corruption primitive: **+2**. `rx_hash_key_len` is user supplied and was passed to `memcpy()` without checking against `req->hashkey`.
* Strong LPE plausibility: **+2**. This is an OOB kernel write / heap overflow candidate with userspace influenced length, so privilege escalation is plausible even if not demonstrated.
* Reliable kernel crash / strong DoS: **+1**. Overwriting adjacent kernel memory can realistically crash the kernel.
* Confidentiality impact plausible: **+1**. Kernel memory corruption can plausibly affect confidentiality in worst case.
* Integrity impact plausible: **+1**. Kernel heap overwrite can plausibly corrupt kernel control or data structures.
* Availability impact realistic: **+1**. Kernel crash is a realistic direct impact.
* Privileged kernel/device-management memory corruption path: **+1** for paranoid score. The corruption occurs inside an RDMA device driver control path.
* Rare / device-specific exposure: **-1**. This requires MANA RDMA hardware or virtual device exposure and access to the RDMA userspace interface.

## 3. Reachability analysis

The bug is not directly network reachable as packet parsing. It is reachable by a local process that can access the RDMA MANA userspace interface, typically `/dev/infiniband/uverbs*` with suitable device permissions. Full root privileges are not necessarily required in RDMA-enabled deployments because uverbs devices are often delegated to users, service accounts, or containers. Containers can matter if the RDMA device node is passed through or if RDMA cgroup and device permissions allow access. The affected subsystem is device-specific, but in Azure environments MANA can be practically relevant.

## 4. Severity interpretation

This behaves like an **Important-class kernel vulnerability candidate**, not an ordinary Moderate. The patch explicitly states that userspace can trash kernel memory, and the fix is a bounds check before a `memcpy()` into a fixed-size destination. Realistic evidence supports kernel memory corruption and DoS. Privilege escalation is not proven by the patch alone, but the primitive is strong enough that manual review should assume LPE plausibility until disproven.

## 5. One-sentence report phrase

A userspace controlled `rx_hash_key_len` in RDMA/mana was used as a `memcpy()` length without bounds checking, allowing a local process with RDMA uverbs access to overflow a kernel buffer and potentially crash the kernel or escalate privileges.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

This is user-triggerable kernel memory corruption with a plausible privilege-escalation path, even though exposure depends on MANA RDMA device availability and uverbs access.

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

Patch: RDMA/mana: Validate rx_hash_key_len [ Upstream
Commit: 7d7c9f0fcd19c4d2f0164347c58d49cafa961b72
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d7c9f0fcd19c4d2f0164347c58d49cafa961b72

Changed files:
  drivers/infiniband/hw/mana/qp.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=7d7c9f0fcd19c4d2f0164347c58d49cafa961b72

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

The original Linux kernel CVE announcement for CVE-2026-46145 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46145

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: Not available
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 8
  Paranoid ActionableScore: 9

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).