[CVE-2026-98416][LOW] dmaengine: ti: k3-udma-glue: fix NULL dereference in k3_udma_glue_release_rx_chn()

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

CVE: CVE-2026-98416
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: dmaengine: ti: k3-udma-glue: fix NULL dereference in k3_udma_glue_release_rx_chn()
Commit: b51ed7885ab0e8ecad765adc13b465cb1498cdc9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b51ed7885ab0e8ecad765adc13b465cb1498cdc9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98416
Analysis date: Wed, 14 Oct 2026 23:31:56 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-98416 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98416

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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

CVE-2026-98416	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98416 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (independent Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the TI K3 UDMA glue cleanup path when allocation of rx_chn flows fails and k3_udma_glue_release_rx_chn continues into flow release with an unallocated flows array. The demonstrated primitive is an invalid NULL read during error cleanup rather than a use after free or an out of bounds memory access. The likely impact is a kernel Oops or panic and denial of service on systems using the affected TI K3 UDMA hardware. For the CVSS the PR:L value in the paranoid score assumes a restricted service or limited local user can repeatedly cause a DMA consumer to request or reinitialize channels while memory allocation is under pressure. Normal deployments are more likely to require administrative or kernel controlled device operations and therefore use PR:H in the base score. The issue is not directly network reachable and no confidentiality or integrity impact is supported by the available code path. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3. The independent weaker Aegis shadow evaluated CVSS 2.7 and ActionableScore 0 with primitive class CLASS_C and manual review NO. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	KASAN NULLPTR SIMPLEFIX ERRORPATH MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash or strong DoS. A failed allocation leaves `rx_chn->flows` NULL, after which the cleanup loop calls `k3_udma_glue_release_rx_flow()` and dereferences it.
* No UAF, repeated release, refcount mutation, OOB access, controlled overwrite, disclosure, or authorization bypass is established.
* No local-unprivileged bonus. Userspace control over the complete channel-request and allocation-failure sequence is not established.
* No privilege penalty. Host-admin-equivalent privilege is not positively established.
* No hardware penalty. The path requires TI K3 UDMA hardware, but the evidence does not establish physical attacker access or sufficiently rare and unreachable hardware.
* No extra Availability point. It would duplicate the same NULL-dereference crash.
* B5-R does not apply because there is no heap OOB write or retry-accumulated index.
* B3-PENDING does not apply because there is no shared-backing write.
* B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW.

3. Reachability analysis

The failure occurs during a kernel channel-request error path after `devm_kcalloc()` fails. The supplied evidence does not identify a direct userspace, network, namespace, or delegated-capability interface that can reliably request the affected channel while forcing this specific allocation failure.

The complete privilege boundary is therefore unresolved, so `HostAdminRequired` and `RequiresHostUID0` remain UNKNOWN rather than being inferred as either privileged or unprivileged. No namespace-scoped trigger is shown. A system must contain and use the affected TI K3 UDMA hardware and a corresponding kernel consumer. This is an ordered allocation-failure cleanup path, not a race.

4. Primitive and severity interpretation

The exact primitive is a NULL-pointer dereference during error cleanup. It is an invalid read through an unallocated `flows` array, not stale post-lifetime storage and not an active structured-object UAF.

There is no first lifetime-ending operation followed by a second release or refcount mutation. The demonstrated consequence is a kernel Oops or possible panic. No useful corruption primitive remains after excluding the crash, and no confidentiality, integrity, privilege-escalation, or security-boundary consequence is supported.

This is CLASS_C. `ImportantCandidate=NO` because the patch establishes crash-only invalid-state behavior. `AutoDowngradeAllowed=YES` because no unresolved corruption, ownership, lifetime, or authorization primitive would be lost.

5. One-sentence report phrase

A failed rx_chn flows allocation can make the TI K3 UDMA cleanup path dereference NULL and cause a kernel Oops or panic, but no memory corruption or security-boundary primitive is established.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a hardware-specific allocation-failure cleanup NULL dereference with no established attacker-controlled corruption or below-host-admin trigger.

7. Call-site confidence

Call-site confidence: medium

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

Patch: dmaengine: ti: k3-udma-glue: fix NULL dereference in k3_udma_glue_release_rx_chn()
Commit: b51ed7885ab0e8ecad765adc13b465cb1498cdc9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b51ed7885ab0e8ecad765adc13b465cb1498cdc9

Commit description:

If devm_kcalloc() for rx_chn->flows fails in a channel request function,
the error path calls k3_udma_glue_release_rx_chn(), which dereferences
the NULL rx_chn->flows pointer in k3_udma_glue_release_rx_flow().

Skip the flow release loop in k3_udma_glue_release_rx_chn() when
rx_chn->flows is not allocated.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d702419 ("dmaengine: ti: k3-udma: Add glue layer for non DMAengine users")
Cc: stable@vger.kernel.org
Reported-by: Pavel Zhigulin <Pavel.Zhigulin@kaspersky.com>
Signed-off-by: Alexander Chesnokov <Alexander.Chesnokov@kaspersky.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260812053426.3521589-1-Alexander.Chesnokov@kaspersky.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/dma/ti/k3-udma-glue.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=b51ed7885ab0e8ecad765adc13b465cb1498cdc9

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

The original Linux kernel CVE announcement for CVE-2026-98416 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98416

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:H/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:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: unknown
  Paranoid ActionableScore: 1

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).