* [CVE-2026-89856][MODERATE REGULAR] scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation
@ 2026-09-16 13:40 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-16 13:40 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-89856
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation
Commit: cf623d32761b00f221a9cfded3303d56e84b429d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf623d32761b00f221a9cfded3303d56e84b429d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89856
Analysis date: Wed, 16 Sep 2026 09:40:45 -0400
ActionableScore: 3
ActionableScore lower bound: 2
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-2026-89856 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89856
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-2026-89856 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-89856 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-681;CWE-191;*CWE-787;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.7';DESCR 'A queue count truncation in qla2xxx can occur because msix_count is u16 while max_req_queues, max_rsp_queues, and max_qpairs are u8. A board or hot-plugged device that reports 257 MSI-X vectors can make msix_count minus 1 become 256 and then truncate to 0, while target mode can also underflow a zero count to 255. When the count is 0, qla2x00_alloc_queues can receive a zero object count and return ZERO_SIZE_PTR, after which ha req_q_map(0) is written through an invalid pointer. For the CVSS the PR:N is used for the paranoid physical device interpretation, because the attacker does not need an OS account on the victim but needs control of hardware presented to the driver. The issue is not network reachable. Impact is at least denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to an invalid kernel write, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES OOB DANGER KERNEL_PANIC_PLUS_UAF HARDWARE LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline / manual review recommended**::
No floor or cap was applied. The paranoid score is higher because the patch explicitly says the ZERO_SIZE_PTR store may corrupt memory or crash the kernel, but the target is highly constrained and no useful attacker controlled corruption primitive is demonstrated.
2. Signal breakdown
Positive signals:
* +1 Constrained kernel corruption candidate. The bug can cause `ha->req_q_map[0] = req` after `req_q_map` is effectively `ZERO_SIZE_PTR`, producing an invalid kernel write.
* +1 Reliable kernel crash / strong DoS. The supplied commit text explicitly describes faulting on the first store and crashing the kernel.
* +1 Firmware or device mediated external influence. The bad value can come from a board or a misconfigured or malicious hot plugged device advertising problematic MSI-X vector counts.
* +1 Memory layout invariant restoration. The patch restores consistency between `u16 msix_count`, `u8` queue counters, allocation counts, and later indexed queue-map writes.
Negative signals:
* -2 Physical or hardware mediated requirement in the conservative score. The attacker influence is through qla2xxx hardware or a device presented to the driver, not through a normal local syscall, network packet, or namespace interface.
* -1 Hardware mediation in the paranoid score. The hardware requirement is still material, but the score keeps more sensitivity because the write is an actual kernel invalid write rather than only a warning or device-local failure.
Non-awarded signals:
* Controlled reclaim not demonstrated.
* Arbitrary or attacker-directed kernel write not demonstrated.
* Attacker-controlled target is not demonstrated. The apparent write target is the fixed low ZERO_SIZE_PTR-derived address.
* Local unprivileged trigger not established.
* Remote network reachability not established.
* Real UAF not established.
* Concrete repeated release/refcount mutation not present.
* C/I impact not awarded as separate positive points because the patch does not establish disclosure, protected-object modification, controlled target selection, or privilege escalation.
* Extra availability point not awarded because the same crash is already counted once.
3. Reachability analysis
The plausible trigger is device or firmware mediated. A qla2xxx board, misconfigured device, malicious hot-plugged device, or possibly a virtualized device presented to the driver can advertise an MSI-X count such as 257, causing `msix_count - 1` to become 256 and then truncate to zero when stored in `u8` queue counters.
This is not directly network reachable. It is also not a normal local unprivileged kernel API. The supplied evidence does not prove that a host administrator is required in all cases, because a malicious physical or hot-plugged device may not require an OS account on the victim. However, the complete privilege and deployment boundary is not fully resolved, so `HostAdminRequired=UNKNOWN`.
Namespace-scoped privilege does not apply. There is no evidence that the complete trigger can be created inside an attacker-controlled namespace. Prior host setup may exist in practice if the device must be installed, assigned, emulated, or hot-plugged by an administrator, but the patch itself mainly establishes the device-supplied MSI-X count as the source of the invalid queue value.
No race is involved. The trigger is an ordered initialization/configuration path, not a timing window.
4. Primitive and severity interpretation
The exact primitive is integer truncation and underflow in queue-count derivation, leading to zero queue allocation and then a store through a ZERO_SIZE_PTR-derived pointer. This is not a UAF and not a repeated release/refcount bug.
The primitive is best treated as `CLASS_B` because there is a concrete kernel invalid write and potential memory corruption, but exploitation leverage is highly constrained. The demonstrated outcome is kernel fault or crash. The speculative stronger consequence is limited memory corruption, but there is no evidence of target selection, attacker-shaped replacement memory, controlled payload beyond a kernel pointer value, or a path to privilege escalation.
This is not `CLASS_A` because no arbitrary write, directed write, controlled reclaim, callback influence, credential manipulation, or demonstrated LPE is established. It is stronger than pure `CLASS_C` because the code performs an actual invalid write, not merely a passive invalid read or warning.
`ImportantCandidate=NO` because the hardware-mediated and fixed-target nature of the write substantially limits practical exploitation, and no meaningful unresolved Important-grade leverage is shown. `AutoDowngradeAllowed=YES` because this appears suitable for ordinary or borderline Moderate handling after recording that it is a constrained kernel corruption candidate, not an automatically Important issue. Manual review is still recommended because the patch explicitly involves an invalid kernel write and possible corruption.
5. One-sentence report phrase
A qla2xxx MSI-X queue count truncation can turn a device supplied vector count into a zero queue allocation and a subsequent ZERO_SIZE_PTR write, causing a kernel crash and limited constrained memory corruption risk through a hardware mediated trigger.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
The issue contains a concrete invalid kernel write, but the trigger is hardware mediated and the write target appears fixed and highly constrained, so manual review is useful but an Important classification is not established from the supplied evidence.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation
Commit: cf623d32761b00f221a9cfded3303d56e84b429d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf623d32761b00f221a9cfded3303d56e84b429d
Commit description:
ha->msix_count is u16, but ha->max_req_queues, ha->max_rsp_queues and
ha->max_qpairs are u8. Deriving the queue count as
"ha->max_req_queues = ha->msix_count - 1" therefore truncates: a board
(or a misconfigured/malicious hot-plugged device) advertising 257 MSI-X
vectors yields msix_count - 1 == 256, which truncates to 0. An MSI-X
count of 1 zeroes it as well, and in target mode the subsequent
"ha->max_req_queues--" then underflows 0 to 255.
When the count is 0, qla2x00_alloc_queues() calls
kzalloc_objs(struct req_que *, 0), which returns ZERO_SIZE_PTR. That is
not NULL, so the allocation check passes and the following
"ha->req_q_map[0] = req" dereferences ZERO_SIZE_PTR, corrupting memory
or crashing the kernel.
Add qla_calc_queue_count() to clamp the derived value into
[1, QLA_MAX_QUEUES - 1] so it always fits in u8 and is never zero, and
use it at all three derivation sites (qla25xx_iospace_config(),
qla83xx_iospace_config() and qla24xx_enable_msix()). Also guard the
target-mode decrement so it cannot reintroduce a zero (which would in
turn underflow max_qpairs).
Fixes: d745952 ("scsi: qla2xxx: Add multiple queue pair functionality.")
Cc: [email protected]
Reported-by: Sashiko <[email protected]>
Signed-off-by: Nilesh Javali <[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/scsi/qla2xxx/qla_inline.h
drivers/scsi/qla2xxx/qla_isr.c
drivers/scsi/qla2xxx/qla_os.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=cf623d32761b00f221a9cfded3303d56e84b429d
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-89856 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89856
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:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS score: 5.7
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: 2
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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