* [CVE-2026-80790][MODERATE 7.0] nvmet-fc: fix invalid free in LS IOD error path
@ 2026-09-04 15:52 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-04 15:52 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80790
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: nvmet-fc: fix invalid free in LS IOD error path
Commit: b189c6e408896ccc23d2e76d7738847cdebf1532
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b189c6e408896ccc23d2e76d7738847cdebf1532
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80790
Analysis date: Fri, 04 Sep 2026 11:52:59 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES
Summary:
An invalid free in the `nvmet-fc` LS IOD allocation unwind path can free an address before the allocated object when request-buffer allocation or DMA mapping fails, causing kernel allocator corruption or crash and requiring manual review despite the typically privileged local trigger.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80790 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80790
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
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CVE-2026-80790 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80790 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:L/UI:N/S:U/C:H/I:H/A:H';CWE-763;CWE-590;CWE-119;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'An invalid free in the nvmet-fc LS IOD allocation error path occurs because nvmet_fc_alloc_ls_iodlist advances the iod pointer while initializing the array and then frees the advanced pointer during unwind. If request buffer allocation or response buffer DMA mapping fails, the unwind path can call kfree on an address outside the allocated object, which is a kernel memory corruption condition. For the CVSS the PR:L is used in the paranoid score because reduced storage administration rights, container root, or delegated target setup may be enough in some deployments, although typical direct target port creation is administrative. The issue is not network reachable by itself and is triggered through local NVMe target setup or fault and resource failure conditions. Impact is at least local denial of service via KASAN report or kernel crash and in worst case may allow confidentiality or integrity impact due to invalid free memory corruption and should be reviewed manually. YES REQUIRES MANUAL CHECK';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4) YES OOB DANGER NVME ERRORPATH UAF DMAorINTERRUPT LINUS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN5 NO NO guess
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ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
ActionableScoreLower=3
## 1. ActionableScore
* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::
## 2. Signal breakdown
Conservative signals:
* +2 Memory corruption, strong corruption primitive: the error path calls `kfree()` on an advanced pointer before the allocated LS IOD array base, producing a concrete invalid free.
* +1 Real lifetime corruption: the bug corrupts allocator lifetime semantics by freeing the wrong address.
* +1 Reliable kernel crash / strong DoS: KASAN reports an invalid free during target port registration, and production kernels may crash or corrupt allocator state.
* +1 Privileged kernel/device-management memory corruption path: the issue is in NVMe target FC setup and DMA-adjacent allocation error handling.
* +1 Important filesystem/storage path: NVMe target is a storage fabric subsystem.
* -2 Requires admin/root/CAP-level privileges in typical deployments: target port creation and fault injection are normally administrative.
* -1 Hard or special triggering conditions: the demonstrated reproducer needs `nvme-fcloop` plus failslab `fail-nth=6`, or real allocation/DMA mapping failure.
Conservative total: 3.
Paranoid adjustment:
* +1 Weak LPE concern: invalid free is allocator memory corruption and may have consequences beyond DoS, but no controlled reclaim, overwrite, or object replacement is shown.
* Privilege penalty softened from -2 to -1 in paranoid interpretation because delegated storage administration, container root, or service-managed NVMe target setup may reduce practical privilege requirements.
Paranoid total: 5.
Call-site confidence: medium-high. The patch and commit identify the failing allocation/unwind function and KASAN call path, but broader caller context is not fully shown in the supplied diff.
## 3. Reachability analysis
The realistic trigger is local and administrative: creating or registering an NVMe FC target port while an allocation or DMA mapping failure occurs. The supplied reproducer uses `nvme-fcloop` and failslab fault injection, which normally requires privileged local control.
This is not directly network reachable. A remote FC initiator is not shown to directly control the vulnerable target-port allocation error path. Firmware-mediated external influence is also not strongly supported by the supplied patch.
Namespaces and containers can matter if NVMe target configuration or configfs access is delegated to a reduced-privilege storage service or container root. In ordinary deployments, however, this remains a host-admin path.
The path is not default-enabled for most systems because NVMe FC target support and target-port configuration are specialized storage features.
## 4. Severity interpretation
This is not an ordinary low-risk cleanup because the primitive is a concrete invalid free, not just a leak or warning. The demonstrated impact is local DoS through KASAN invalid-free detection or possible allocator corruption.
Realistic privilege escalation is not demonstrated. The dangerous part is theoretical allocator memory corruption in a privileged storage subsystem, which justifies manual review and an Actionable Moderate bucket, but not a Strong Important classification on the supplied evidence alone.
YES REQUIRES MANUAL CHECK
## 5. One-sentence report phrase
An invalid free in the `nvmet-fc` LS IOD allocation unwind path can free an address before the allocated object when request-buffer allocation or DMA mapping fails, causing kernel allocator corruption or crash and requiring manual review despite the typically privileged local trigger.
## 6. Manual review recommendation
MANUAL CHECK REQUIRED.
Reason: this is confirmed kernel memory corruption through invalid free in a storage target subsystem, even though the demonstrated trigger is privileged and failure-injection dependent.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: nvmet-fc: fix invalid free in LS IOD error path
Commit: b189c6e408896ccc23d2e76d7738847cdebf1532
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b189c6e408896ccc23d2e76d7738847cdebf1532
Commit description:
nvmet_fc_alloc_ls_iodlist() advances iod while initializing the LS IOD
array. If an rqstbuf allocation or response buffer DMA mapping fails,
the unwind loop decrements iod past the start of the array. The final
kfree(iod) therefore frees an address before the allocated object.
This can be reproduced with nvme-fcloop and failslab by setting
fail-nth to 6 before creating a target port. KASAN reports:
BUG: KASAN: invalid-free in nvmet_fc_register_targetport
Free of addr ffff88816cf8ff48 by task nvmet_fail_nth/9552
Free the original allocation base stored in tgtport->iod instead. With
this fix applied, the same sysfs write with fail-nth=6 returns -ENOMEM
without any KASAN report.
Fixes: c534320 ("nvme-fabrics: Add target support for FC transport")
Cc: [email protected]
Reviewed-by: Maurizio Lombardi <[email protected]>
Assisted-by: Codex:gpt-5
Signed-off-by: Jiang HongHui <[email protected]>
Signed-off-by: Keith Busch <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/nvme/target/fc.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=b189c6e408896ccc23d2e76d7738847cdebf1532
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80790 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80790
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: 3
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: YES
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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