[CVE-2026-72454][MODERATE 7.0] i3c: mipi-i3c-hci: Fix race in i3c_hci_addr_to_dev() [ Upstream

[CVE-2026-72454][MODERATE 7.0] i3c: mipi-i3c-hci: Fix race in i3c_hci_addr_to_dev() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72454
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: i3c: mipi-i3c-hci: Fix race in i3c_hci_addr_to_dev() [ Upstream
Commit: 8f851cab401c28287d536b1347d76f6e219c0db6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8f851cab401c28287d536b1347d76f6e219c0db6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72454
Analysis date: Sun, 16 Aug 2026 01:45:53 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in the MIPI I3C HCI IBI IRQ path can traverse the I3C device list while it is concurrently modified, creating a stale i3c_dev_desc use-after-free candidate and likely kernel crash on affected hardware.

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

The original Linux kernel CVE announcement for CVE-2026-72454 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72454

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 7.0
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-2026-72454	MODERATE	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:H/I:H/A:H';CWE-362;*CWE-416;CWE-667;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 MIPI I3C HCI IBI path occurs because i3c_hci_addr_to_dev used to walk the shared I3C bus device list from IRQ context while device addition or removal could update the same list under bus lock. Since the IRQ handler cannot take that rwsem, concurrent list mutation can leave the traversal observing a stale or freed i3c_dev_desc, resulting in a use-after-free candidate or a kernel crash. For the CVSS the PR:L is used for the higher manual review score because reliable triggering may be possible for a local actor with delegated I3C device control or with influence over an attached I3C peripheral, while normal administration paths may require stronger privileges. The issue is not network reachable. Impact is at least local denial of service via kernel crash and in the worst case may allow confidentiality or integrity impact due to UAF style memory corruption, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	OOB DANGER NOMEMCHK RACE ERRORPATH UAF DMAorINTERRUPT KERNEL_PANIC_PLUS_UAF HARDWARE MEMORY  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	YES	NO	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Triggered signals:

* Firmware-mediated external influence: +1
  IBI events can be generated by an attached I3C device and are handled in the HCI IRQ path.

* Memory corruption, weak/indirect corruption candidate: +1
  The old code walked `bus->devs.i3c` from IRQ context without the protecting `bus.lock`, so concurrent list mutation could expose a stale `i3c_dev_desc`.

* Real lifetime corruption: +1
  The commit explicitly describes potential use-after-free when device addition/removal races with IRQ-side lookup.

* Reliable kernel crash / strong DoS: +1
  The commit states that the race can lead to crashes.

* Privileged kernel/device-management lifetime path: +1
  The bug affects device lifetime and IBI lookup state inside a trusted hardware interrupt path.

* Availability impact realistic: +1 in paranoid score only
  A crash in IRQ/device handling is host-kernel availability impact, but this is not double-counted in the lower score.

Subtracted signals:

* Hard or unreliable race / special timing required: -1
  Exploitation depends on racing IBI handling with I3C device addition/removal.

* Rare AND difficult-to-reach subsystem/configuration: -1 in lower score only
  MIPI I3C HCI is hardware and platform dependent, not a broad default subsystem.

No strong LPE bonus is awarded. The patch supports a UAF candidate, but does not show attacker-controlled reclaim, object replacement, callback control, refcount takeover, or write-after-free.

Call-site confidence: high. The patch includes the relevant IRQ-side DMA/PIO lookup call sites and the lifetime update points for enable, disable, and free IBI.

## 3. Reachability analysis

The bug is not network reachable. The affected path is the MIPI I3C HCI IBI interrupt handling path.

Typical reliable triggering requires a system with this I3C HCI controller and concurrent I3C device lifecycle activity, such as device addition, removal, IBI disable, or IBI free. In normal deployments, controlling device lifecycle is usually privileged or firmware/platform mediated. However, a malicious or misbehaving attached I3C peripheral may influence IBI timing, so the issue is not purely an administrator-only correctness bug.

Namespaces and containers usually do not make this broadly reachable unless device management or physical device access is delegated into the container. The realistic exploitation condition is platform specific: an affected I3C HCI device must be present and IBI traffic must race with device list mutation.

## 4. Severity interpretation

This behaves above ordinary Moderate because it is an IRQ-path race with an explicit use-after-free candidate. It should not be auto-closed as a simple crash-only driver bug without checking platform exposure.

Realistic impact is most likely kernel crash or device/host DoS. Theoretical memory corruption exists due to stale object traversal, but the supplied patch does not demonstrate a practical privilege-escalation primitive such as controlled reclaim, type confusion, callback dispatch, or arbitrary write.

Therefore this is best treated as Actionable Moderate at minimum. It is not a strong Important candidate on the available evidence, but it deserves manual review because kernel UAF in IRQ context is historically easy to underestimate.

## 5. One-sentence report phrase

A race in the MIPI I3C HCI IBI IRQ path can traverse the I3C device list while it is concurrently modified, creating a stale i3c_dev_desc use-after-free candidate and likely kernel crash on affected hardware.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch explicitly fixes a race that can lead to use-after-free in an IRQ path. Even though practical LPE evidence is not shown and reachability is hardware dependent, this class should not be auto-closed without checking affected platform exposure and whether an attached device or delegated device-management path can reliably trigger the race.

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

Patch: i3c: mipi-i3c-hci: Fix race in i3c_hci_addr_to_dev() [ Upstream
Commit: 8f851cab401c28287d536b1347d76f6e219c0db6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8f851cab401c28287d536b1347d76f6e219c0db6

Changed files:
  drivers/i3c/master/mipi-i3c-hci/core.c
  drivers/i3c/master/mipi-i3c-hci/dma.c
  drivers/i3c/master/mipi-i3c-hci/hci.h
  drivers/i3c/master/mipi-i3c-hci/ibi.h
  drivers/i3c/master/mipi-i3c-hci/pio.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=8f851cab401c28287d536b1347d76f6e219c0db6

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

The original Linux kernel CVE announcement for CVE-2026-72454 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72454

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: 4
  Paranoid ActionableScore: 5

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 7.0

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).