[CVE-2026-98213][MODERATE REGULAR] mmc: core: Cancel SDIO IRQ work before freeing host

[CVE-2026-98213][MODERATE REGULAR] mmc: core: Cancel SDIO IRQ work before freeing host

[AL-KERNEL]

CVE: CVE-2026-98213
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: mmc: core: Cancel SDIO IRQ work before freeing host
Commit: bae1cf4f9902b2065bd78b759c7fe6312855f05e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bae1cf4f9902b2065bd78b759c7fe6312855f05e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98213
Analysis date: Fri, 09 Oct 2026 05:43:40 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-98213 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98213

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-2026-98213	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98213 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, 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:H/I:H/A:H';*CWE-416;CWE-362;*CWE-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A race in the MMC core can leave host sdio_irq_work queued while the associated mmc_host is being removed and freed. If the worker runs after mmc_host_classdev_release has released the host, container_of and later worker accesses can dereference memory that no longer contains a valid mmc_host. The directly supported impact is a local kernel crash or corruption of kernel state. The use after free also creates a plausible worst case risk of privilege escalation if the freed allocation can be reused before the worker accesses it, although reliable control of that reuse is not established by the supplied code. For the CVSS the PR:L in the paranoid score reflects environments where a local service account, reduced capability root, container root, or a user with delegated device management can influence hotplug or controller removal. Reliable triggering on conventional systems will more commonly require administrative device control. The race requires a narrow timing window, so AC:H is appropriate. The issue is not network reachable and normally depends on a host controller that uses sdio_signal_irq.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	MAYBE	UAF LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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

ActionableScore=3
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

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

2. Signal breakdown

* +2 Real UAF / lifetime violation. `sdio_irq_work` can execute after `put_device()` leads to `mmc_host_classdev_release()` freeing the containing `mmc_host`.
* +1 Reliable kernel crash / strong DoS. The worker derives a freed host through `container_of()` and can dereference invalid kernel memory.
* No race penalty. The required interrupt, workqueue, and teardown ordering is specific, but the supplied evidence does not establish that it is sufficiently rare, uncontrollable, or difficult to repeat.
* No privilege penalty. Host-administrator control is plausible for controller removal, but the complete privilege boundary is not positively established.
* No structured stale-object leverage. The affected object is structured, but this is a fixed asynchronous driver-context UAF during teardown. Attacker-controlled reclaim, replacement contents, callbacks, or useful stale-field consumption are not established.
* No repeated release/refcount signal. The worker dereferences a freed host, but it does not perform a demonstrated second put, free, or refcount mutation on the same reference.
* No extra availability point. The same possible kernel crash is already counted.
* No confidentiality, integrity, weak-LPE, or strong-LPE points. Controlled reclaim, disclosure, directed writes, and privilege escalation are not demonstrated.
* B5-R does not apply. There is no confirmed heap OOB write, retry-accumulated index, or later consumption of retry-corrupted descriptors.

Repeated-release checks:

* First lifetime-ending operation: `put_device()` may cause release and free the host.
* Exact stale reference survives: queued work embedded in the host may survive operationally and execute.
* Second lifetime/refcount mutation: no.
* Concrete repeated release/refcount +1: not awarded.
* Paranoid repeated-refcount +1: not awarded.
* FLOOR 5: not applied.

3. Reachability analysis

The vulnerable sequence requires an MMC host controller using `sdio_signal_irq()`, a pending SDIO IRQ work item, and concurrent controller removal or host release. The supplied material does not establish whether an ordinary user, delegated device-management service, removable-device action, or only a host administrator can complete that sequence. Therefore `HostAdminRequired` remains `UNKNOWN`.

No namespace-scoped capability path is shown. No remote or network trigger exists. Suitable MMC/SDIO hardware and driver behavior are prerequisites, but the evidence does not establish that the hardware is sufficiently rare to justify a hardware penalty. The race requires teardown near IRQ work scheduling, while practical repeatability remains unresolved.

4. Primitive and severity interpretation

The exact primitive is asynchronous post-teardown use of a freed `mmc_host`. It is a real Class B UAF involving a fixed driver context whose embedded work item remains queued after its owner may be freed.

The demonstrated path is primarily teardown-related and supports a stale dereference and kernel crash. It does not establish controlled replacement, post-free attacker data, a callback hijack, arbitrary read or write, repeated lifetime mutation, or another independently useful primitive after excluding the crash.

This is category A in the cleanup distinction: an ordinary stale asynchronous dereference. It is not category B repeated lifetime corruption because no second release or refcount mutation is demonstrated.

`ImportantCandidate=NO` because the available evidence supports a constrained crash-oriented UAF rather than meaningful unresolved Important-grade leverage. `AutoDowngradeAllowed=YES` because no controlled corruption, repeated lifetime mutation, authorization bypass, or security-boundary primitive remains unresolved. Operational severity is likely Moderate, subject to confirming who can initiate the complete removal sequence.

5. One-sentence report phrase

A pending SDIO IRQ worker can dereference an MMC host after teardown has freed it, creating a constrained asynchronous use-after-free that can crash the kernel without an established controlled-reuse or privilege-escalation primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm the worker operations, allocator reuse opportunities, supported host drivers, and whether device removal is reachable below host-administrator privilege.

7. Call-site confidence

Call-site confidence: medium

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

Patch: mmc: core: Cancel SDIO IRQ work before freeing host
Commit: bae1cf4f9902b2065bd78b759c7fe6312855f05e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bae1cf4f9902b2065bd78b759c7fe6312855f05e

Commit description:

A host controller that uses sdio_signal_irq() schedules host->sdio_irq_work
from its interrupt handler.  That work is only cancelled on the suspend
path (mmc_sdio_suspend()), not on the remove/free path, so a worker armed
just before the controller freed its IRQ can run after
mmc_host_classdev_release() has freed the host and dereference it through
container_of().

Cancel host->sdio_irq_work in mmc_free_host(), like the existing
host->detect drain added by commit 1036f69 ("mmc: core: Cancel
delayed work before releasing host").

This issue was found by an in-house static analysis tool.

Fixes: 6826966 ("mmc: sdio: Add API to manage SDIO IRQs from a workqueue")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Signed-off-by: Ulf Hansson <ulfh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/mmc/core/host.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=bae1cf4f9902b2065bd78b759c7fe6312855f05e

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

The original Linux kernel CVE announcement for CVE-2026-98213 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98213

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:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 3

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).