[CVE-2026-93822][MODERATE REGULAR] PCI: iproc: Protect root bus removal with rescan lock [ Upstream

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

CVE: CVE-2026-93822
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: PCI: iproc: Protect root bus removal with rescan lock [ Upstream
Commit: bd2bf1e0d973c93fc1637b90cbb9a5a5f6884bd3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd2bf1e0d973c93fc1637b90cbb9a5a5f6884bd3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93822
Analysis date: Thu, 24 Sep 2026 13:26:34 -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-2026-93822 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93822

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: NO

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

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

CVE-2026-93822	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93822 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/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: '6.4';DESCR 'A race condition in the iproc PCI controller driver can occur when a root PCI bus is stopped and removed while concurrent PCI rescan or hotplug operations access the same bus structures. The race may result in use after free conditions or a kernel crash if a concurrent operation dereferences PCI objects after root bus removal has started. For the CVSS the PR:H reflects that reliable triggering normally requires administrative access to PCI sysfs rescan or hotplug controls such as CAP_SYS_ADMIN. The issue is not directly network reachable and requires a local race window. Impact is at least local denial of service through a kernel crash. In the worst case the stated use after free condition may allow confidentiality or integrity impact and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	DANGER RACE UAF KERNEL_PANIC_PLUS_UAF LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=1
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +2 Real UAF or lifetime violation. The commit directly identifies a race between root bus removal and concurrent PCI rescan or hotplug activity that may use PCI bus objects after removal begins.
* +1 Kernel crash or strong DoS. The stated consequence includes possible system crashes caused by the removal versus rescan or hotplug race.
* -2 Host-admin-equivalent privilege requirement. Triggering the complete sequence requires control of PCI sysfs rescan or hotplug operations and root bus removal or driver unbind activity. These are normally protected by host CAP_SYS_ADMIN level permissions.

Not awarded:

* No controlled reclaim or attacker-controlled replacement of freed PCI objects is demonstrated.
* No arbitrary or directed kernel write is demonstrated.
* No confidentiality or integrity consequence is demonstrated.
* No remote reachability is established. The relevant operations are local PCI management control-plane operations.
* No attacker-controlled active-object reuse or structured stale-field consumption is shown by the supplied patch.
* No concrete repeated release, put, or refcount mutation through the same dangling reference is established.
* No hard-race penalty was applied. The bug is a race, but the supplied material does not establish an unusually narrow or uncontrollable timing condition beyond ordinary concurrent operations.
* No paranoid increment was awarded. The commit mentions possible UAF, but does not establish a reclaim, type confusion, stale callback, post-free write, disclosure, or other exploitation primitive beyond the potential stale-object access and crash.

3. Reachability analysis

The evaluated attacker is a local host administrator or a process holding host-admin-equivalent PCI management privileges. The vulnerable sequence involves stopping and removing an iProc PCI root bus while concurrent PCI rescan or hotplug operations are initiated through sysfs.

PCI rescan and removal control operations are host-level PCI subsystem management actions. The supplied context does not support a trigger entirely inside an unprivileged user namespace or a network namespace. NamespaceScopedPrivilege is therefore NO.

There is no network packet trigger and no special external hardware access is required by the patch itself. However, the complete attacker-controlled trigger requires privileged control over the host PCI topology and sysfs management interfaces. Repeated attempts may be possible for a privileged actor, but no attacker-controlled post-free reuse mechanism is established.

4. Primitive and severity interpretation

The patch addresses a concrete lifetime synchronization defect. `iproc_pcie_remove()` removes a root PCI bus without holding `pci_rescan_remove_lock`, while concurrent sysfs-driven rescan or hotplug paths can access the same PCI hierarchy. The added lock establishes that root bus stop and removal must be serialized with those operations.

The affected state is an active structured PCI bus hierarchy rather than fixed stale storage. However, the supplied patch and commit do not show which stale fields are consumed after removal, whether freed bus or device memory can be reclaimed in an attacker-controlled manner, or whether any stale access proceeds beyond an immediate crash.

This is CLASS_B because a real UAF or equivalent post-lifetime PCI-object access is directly implied by the stated race. It is not CLASS_A because no controlled replacement, active post-free object interpretation, callback control, refcount takeover, arbitrary read or write, disclosure, policy bypass, or privilege escalation is established.

The demonstrated practical consequence is local host-wide denial of service through a possible kernel crash. A stronger consequence is speculative only. ImportantCandidate is NO because the available evidence describes a host-admin-gated PCI management race with crash behavior but does not establish meaningful exploitation leverage beyond that crash. AutoDowngradeAllowed is YES because no unresolved controlled corruption or boundary-bypass primitive is demonstrated.

5. One-sentence report phrase

A race between iProc PCI root bus removal and concurrent sysfs PCI rescan or hotplug operations may cause use after free access to PCI bus objects and a local kernel crash, but triggering requires host administrative PCI management privileges.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The commit explicitly identifies possible use after free behavior, but the patch does not expose the stale access path, object reuse conditions, or exact privilege checks needed to determine whether the issue is strictly crash-only.

7. Call-site confidence

Call-site confidence: medium

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

Patch: PCI: iproc: Protect root bus removal with rescan lock [ Upstream
Commit: bd2bf1e0d973c93fc1637b90cbb9a5a5f6884bd3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd2bf1e0d973c93fc1637b90cbb9a5a5f6884bd3

Changed files:
  drivers/pci/controller/pcie-iproc.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=bd2bf1e0d973c93fc1637b90cbb9a5a5f6884bd3

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

The original Linux kernel CVE announcement for CVE-2026-93822 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93822

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:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 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).