[CVE-2026-93037][MODERATE REGULAR] RDMA/hfi1: Propagate sdma_txinit_ahg() errors [ Upstream

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

CVE: CVE-2026-93037
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: RDMA/hfi1: Propagate sdma_txinit_ahg() errors [ Upstream
Commit: cb73c2fe6e9cf563c99f22b7c8bca0d5f70d603e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cb73c2fe6e9cf563c99f22b7c8bca0d5f70d603e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93037
Analysis date: Thu, 17 Sep 2026 21:01:06 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93037 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93037

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
======================================================================

CVE-2026-93037	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93037 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-252;*CWE-457;CWE-665;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'An ignored error return in the RDMA hfi1 user SDMA path can let request processing continue after sdma_txinit_ahg fails before txreq initialization. This may leave an uninitialized kernel transmit request in the later SDMA processing path and can cause a kernel crash or undefined driver behavior. For the CVSS the PR:L is used because a local user or process with access to the hfi1 RDMA user SDMA interface is needed to submit the affected request. The issue is not directly network reachable from a remote host and is triggered through the local RDMA device interface. Impact is at least local denial of service via kernel crash. In the paranoid interpretation, limited confidentiality or integrity impact is possible because an uninitialized kernel request object may be consumed by the transmit path, but the patch context does not show a reliable arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4)	YES	KASAN INIT SIMPLEFIX NETWORK  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	NO	NO	checked

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

ActionableScore=4
ActionableScoreLower=3
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 3. No floor or cap applied.
* Raw paranoid score: 4
* Paranoid score: 4. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

Positive conservative signals:

* +1 Weak or indirect corruption candidate. `sdma_txinit_ahg()` may fail before initializing `tx->txreq`, but the caller continued as if initialization succeeded.
* +1 Realistic kernel crash or strong DoS concern. A later SDMA transmit path may consume an uninitialized kernel transmit request.
* +1 Below-host-admin local reachability. The affected code is in the hfi1 user SDMA path, so a local process with access to the hfi1 RDMA user interface can plausibly submit the affected request.

Positive paranoid-only signals:

* +1 Local high-control kernel data-plane API concern. User SDMA requests provide attacker-influenced request parameters in a DMA/transmit path, so the uninitialized `txreq` consumption deserves manual review even though a concrete exploit primitive is not shown.

Negative signals:

* No negative privilege penalty applied. Host-admin-equivalent privilege is not established by the supplied evidence.
* No race or timing penalty applied. This is an ordered error-propagation bug, not a demonstrated narrow race.
* No rare-hardware penalty applied in the numeric score. hfi1 hardware is specialized, but the vulnerable product configuration is precisely a system exposing hfi1 user SDMA.

Important non-awarded signals:

* RealUAF not awarded. The patch does not establish a use-after-free or stale post-lifetime reference.
* Concrete repeated release/refcount not awarded. There is no first put/free followed by a second lifetime mutation on the same dangling reference.
* Strong exploitation leverage not awarded. Controlled reclaim, arbitrary write, callback control, refcount takeover, or demonstrated LPE are not shown.
* Structured stale-object leverage not separately awarded. The issue is an uninitialized transmit request, but the patch does not show a distinct post-reuse structured-object primitive.
* Confidentiality and integrity impact not awarded. Limited C/I remains a paranoid CVSS concern, but the ActionableScore evidence does not establish disclosure or unauthorized modification.
* Extra availability not awarded. The same possible crash is counted only once.
* Remote reachability not awarded. RDMA fabric involvement does not make this directly network-triggerable without local RDMA user-interface access.

3. Reachability analysis

The likely trigger is a local process that can access the hfi1 RDMA user SDMA interface and submit a request that reaches `set_txreq_header_ahg()`. The supplied evidence does not show a direct remote packet path to the vulnerable operation.

Host administrator privilege is not positively established as required for the complete trigger, because this is a `user_sdma` path intended for userspace RDMA operation. However, practical reachability depends on device permissions, RDMA stack configuration, and the presence of hfi1 hardware.

Namespace-scoped privilege is not applicable from the supplied evidence. No network namespace or user namespace capability path is established.

Prior setup exists in the practical sense that the system must have hfi1 hardware and expose the RDMA user interface, but the prompt evidence does not prove that the attacker must perform host-admin setup to trigger the bug once access exists.

No hard race is involved. The vulnerable sequence is: helper failure, ignored return value, continued request processing with uninitialized `txreq`.

4. Primitive and severity interpretation

The exact primitive is unchecked error propagation leading to possible use of an uninitialized kernel transmit-request structure. `sdma_txinit_ahg()` can return before initializing `tx->txreq`, while `set_txreq_header_ahg()` previously ignored that failure and returned a positive AHG change count.

This is not a demonstrated UAF, not a double-free, and not a concrete repeated refcount mutation. It is best classified as invalid-state or uninitialized-object consumption in a kernel DMA/transmit path.

PrimitiveClass is CLASS_C because the patch establishes crash or undefined driver behavior risk, but not an independently useful corruption primitive such as controlled overwrite, controlled reclaim, arbitrary read/write, callback hijack, or ownership-boundary violation.

The demonstrated practical consequence is local DoS or kernel instability. The speculative consequence is stronger memory corruption if later SDMA code consumes uninitialized fields in an exploitable way, but the supplied patch does not establish that leverage.

ImportantCandidate is NO because there is no concrete UAF, repeated lifetime mutation, controlled corruption, authorization bypass, or demonstrated privilege escalation. ManualReview is RECOMMENDED because the bug is in a kernel user SDMA transmit path and the failed initialization leaves a nontrivial kernel request object in an invalid state.

AutoDowngradeAllowed is YES because no unresolved Class A or strong Class B primitive is established. This can be handled as borderline Moderate unless additional analysis shows that uninitialized `txreq` fields can influence memory access, callbacks, DMA descriptors, or lifetime state in a controlled way.

5. One-sentence report phrase

An ignored `sdma_txinit_ahg()` error in the RDMA hfi1 user SDMA path can allow request processing to continue with an uninitialized `txreq`, creating a local kernel crash or undefined driver behavior risk for users with access to the hfi1 RDMA user interface.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Review is recommended because this is not merely a harmless return-value cleanup: a failed initialization can leave a kernel transmit request uninitialized and still consumed by later SDMA processing. It is not mandatory Important-grade review from the supplied evidence because no UAF, repeated refcount mutation, controlled reclaim, arbitrary write, or demonstrated privilege escalation is established.

7. Call-site confidence

Call-site confidence: medium

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

Patch: RDMA/hfi1: Propagate sdma_txinit_ahg() errors [ Upstream
Commit: cb73c2fe6e9cf563c99f22b7c8bca0d5f70d603e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cb73c2fe6e9cf563c99f22b7c8bca0d5f70d603e

Changed files:
  drivers/infiniband/hw/hfi1/user_sdma.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=cb73c2fe6e9cf563c99f22b7c8bca0d5f70d603e

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

The original Linux kernel CVE announcement for CVE-2026-93037 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93037

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 3
  Paranoid ActionableScore: 4

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).