* [CVE-2026-90389][LOW] md: scope memalloc_noio to allocation critical sections [ Upstream
@ 2026-09-17 23:46 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-17 23:46 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90389
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: md: scope memalloc_noio to allocation critical sections [ Upstream
Commit: 72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90389
Analysis date: Thu, 17 Sep 2026 19:46:46 -0400
ActionableScore: 0
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-2026-90389 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90389
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-2026-90389 LOW https://www.kernelcve.org/list/?q=CVE-2026-90389 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:N/I:N/A:H';CWE-362;CWE-667;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race in MD suspend handling can leak PF_MEMALLOC_NOIO state because a memalloc_noio_save token was stored in the shared mddev object even though the token belongs to the current task. With concurrent sysfs writes to suspend_lo and suspend_hi, one task can enter PF_MEMALLOC_NOIO and return to userspace while another task later restores the saved token. For the CVSS the PR:L is used only for the paranoid score, because some deployments may delegate MD sysfs control to a reduced capability admin service or storage management process rather than full host root. The usual practical case is still PR:H because writing these MD control attributes is normally administrator only. The issue is not network reachable and requires local control plane access to MD configuration. Impact is denial of service or reliability degradation through incorrect memory allocation context, not privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES DISK LEAK HARDWARE LINUS NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 0
* Conservative score: 0. No floor or cap applied.
* Raw paranoid score: 0
* Paranoid score: 0. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1. Concrete invalid per-task allocation-context state is established. A memalloc_noio_save token was stored in shared mddev state even though the token belongs to the current task.
* +1. Availability or reliability degradation is plausible. A task may return to userspace with PF_MEMALLOC_NOIO still set, causing later allocations in that task to behave incorrectly.
* -2. Host-admin-equivalent access is positively supported. The trigger is concurrent writes to MD sysfs suspend attributes and MD array management is normally host administrative control.
* No Real UAF awarded. The patch does not show stale object dereference, post-free access, double release, or refcount mutation through freed storage.
* No controlled reclaim, arbitrary write, information disclosure, privilege escalation, or authorization bypass is established.
* No reliable kernel crash signal is awarded. The demonstrated issue is PF_MEMALLOC_NOIO state leakage and allocation-context mis-scoping, not a panic path.
* No resource/reference leak signal is awarded. This is not a missing put/free of a kernel object.
* No race penalty is needed. The race is real, but the already low score and host-admin trigger capture practical risk.
3. Reachability analysis
The trigger requires local control over MD array management interfaces, specifically concurrent writes to suspend_lo and suspend_hi via sysfs. That is host control-plane access, not a network data-plane trigger. Ordinary unprivileged reachability is not established. Namespace-scoped privilege is not established because MD block-device management is host storage administration, not a complete attacker-created namespace operation. No special hardware beyond MD/RAID usage is required. The race is reproducible according to the supplied reproducer, but it remains gated by privileged MD sysfs access.
4. Primitive and severity interpretation
The exact primitive is a task-state lifetime/scope mismatch: a per-task memalloc_noio token was stored in a shared mddev object, allowing one task to save PF_MEMALLOC_NOIO state and another task to restore it. This is not active structured UAF, not fixed stale storage, and not a repeated release/refcount bug. The demonstrated consequence is local reliability degradation or DoS-like allocation failure behavior for affected management tasks. The speculative consequence would be broader service disruption if a privileged storage-management process is forced into bad allocation behavior, but no memory corruption or privilege escalation primitive is supported. PrimitiveClass is CLASS_C. ImportantCandidate is NO because there is no unresolved kernel corruption or security-boundary primitive. AutoDowngradeAllowed is YES because the issue is host-admin oriented and lacks UAF, OOB, authorization bypass, information leak, or LPE evidence.
5. One-sentence report phrase
A race in MD suspend handling can leak PF_MEMALLOC_NOIO task state across concurrent privileged sysfs writes, causing local reliability degradation or denial of service without evidence of memory corruption or privilege escalation.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: host-admin-only MD control-plane issue with no UAF, no repeated refcount mutation, no security-boundary bypass, and no demonstrated impact beyond local reliability or DoS-like behavior.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: md: scope memalloc_noio to allocation critical sections [ Upstream
Commit: 72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
Changed files:
drivers/md/md-bitmap.c
drivers/md/md.c
drivers/md/md.h
drivers/md/raid5.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=72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90389 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90389
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:L
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: 0
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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