* [CVE-2026-98478][LOW] scsi: ufs: core: Keep internal commands dispatchable during error handling
@ 2026-10-24 14:41 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 14:41 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98478
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: scsi: ufs: core: Keep internal commands dispatchable during error handling
Commit: 9f6f4840def931814c106fc800f57a2d26befee6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9f6f4840def931814c106fc800f57a2d26befee6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98478
Analysis date: Sat, 24 Oct 2026 10:41:00 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
UFS error recovery can deadlock by waiting for an internal command on a queue that recovery itself quiesced, causing storage unavailability without a shown corruption or privilege-bypass primitive.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98478 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98478
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-2026-98478 LOW https://www.kernelcve.org/list/?q=CVE-2026-98478 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-833;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A logic error in UFS error recovery can quiesce the pseudo SCSI request queue together with regular LUN queues. The recovery path then waits for an internal command such as NOP OUT UPIU while blk mq refuses to dispatch that command from the quiesced queue, resulting in an unrecoverable circular wait and loss of storage availability. For the CVSS the PR:L value reflects a local process able to generate UFS backed IO, although reliable triggering also requires the controller to enter error handling and attacker control over that condition is not established. There is no evidence of UAF, out of bounds access, information disclosure, data modification, or a privilege escalation primitive. The issue is not directly network reachable and its demonstrated impact is denial of service. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.5 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 LOW to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE_KPANIC to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation 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 INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 5.3 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. 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 DEADLOCK DISK ERRORPATH HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - 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 base score: 1.
* Conservative score: 1.
* Raw paranoid score: 1.
* Paranoid score: 1.
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable storage availability failure: quiescing the shared tagset also quiesces the pseudo-device queue, while error recovery synchronously waits for an internal request that cannot be dispatched.
* +0 Additional availability: not awarded because it would duplicate the same circular-wait/storage-loss effect.
* +0 Attacker reachability: ordinary UFS-backed I/O is plausible, but attacker control over entry into error handling is not established.
* +0 Memory-corruption or lifetime primitive: no UAF, OOB access, stale reference, overwrite, or refcount misuse is shown.
* +0 Authorization bypass: the patch changes queue dispatch state, not an access-control decision.
* No privilege, race, rarity, or hardware penalty applied because the evidence does not establish the relevant restrictions.
3. Reachability analysis
A local process may issue UFS-backed I/O, but the supplied evidence does not show that it can reliably force the controller into the affected error-recovery state. The complete trigger’s privilege requirement is therefore unknown. No namespace-scoped capability path, prior privileged setup, remote path, or physical attacker requirement is shown. UFS hardware is required, but there is no basis for treating it as rare physical-only exposure.
4. Primitive and severity reading
The defect is a queue-state sequencing error: recovery quiesces the queue needed by its own internal command and then waits indefinitely. This is CLASS_C availability behavior, not active-state corruption or a memory-safety primitive. The demonstrated consequence is storage unavailability; host panic, data corruption, confidentiality loss, authorization bypass, and privilege escalation are unsupported. NEW52/B5-R, NEW53/B3-PENDING, and NEW54/B4-PENDING do not apply.
ImportantCandidate=NO because there is no material corruption, ownership, authorization, or trust-boundary primitive. AutoDowngradeAllowed=YES because the evidence supports only a constrained deadlock/DoS.
5. One-sentence report phrase
UFS error recovery can deadlock by waiting for an internal command on a queue that recovery itself quiesced, causing storage unavailability without a shown corruption or privilege-bypass primitive.
6. Manual review advice
NO MANUAL CHECK NEEDED
The patch and call path clearly establish an availability-only queue deadlock, while attacker control over the prerequisite controller error remains unproven.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: scsi: ufs: core: Keep internal commands dispatchable during error handling
Commit: 9f6f4840def931814c106fc800f57a2d26befee6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9f6f4840def931814c106fc800f57a2d26befee6
Commit description:
Commit 08b12cd ("scsi: ufs: core: Switch to scsi_get_internal_cmd()")
switched UFS internal commands to allocate requests on
hba->host->pseudo_sdev->request_queue, which shares the host tagset with
regular LUNs.
During error recovery, ufshcd_err_handling_prepare() calls
blk_mq_quiesce_tagset(&hba->host->tag_set), marking all queues in the
tagset as quiesced, including pseudo_sdev->request_queue. When
ufshcd_verify_dev_init() subsequently issues internal commands (e.g. NOP
OUT UPIU) via blk_execute_rq(), blk_mq_run_hw_queue() skips running the
quiesced queue, resulting in an unrecoverable circular wait deadlock.
Keep quiescing the tagset and unquiesce the pseudo SCSI device on top of
that, so internal commands stay dispatchable while the logical units remain
quiesced. Re-quiesce the pseudo device before unquiescing the tagset so
that quiesce_depth stays balanced.
Clock scaling and ufshcd_pause_command_processing() are unaffected: they
keep quiescing the whole tagset, internal commands included.
Fixes: 08b12cd ("scsi: ufs: core: Switch to scsi_get_internal_cmd()")
Cc: [email protected]
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Stanley Jhu <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Martin K. Petersen (Oracle) <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/ufs/core/ufshcd.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=9f6f4840def931814c106fc800f57a2d26befee6
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98478 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98478
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:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.5
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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