From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98670][MODERATE 7.0] iio: adc: xilinx-xadc: free IRQ before cancelling the unmask worker on unbind Date: Sun, 18 Oct 2026 23:58:55 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98670 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: a29d385ad7b340c952a3935af2b33488db1eb3a6 List-Id: CVE: CVE-2026-98670 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: iio: adc: xilinx-xadc: free IRQ before cancelling the unmask worker on unbind Commit: a29d385ad7b340c952a3935af2b33488db1eb3a6 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a29d385ad7b340c952a3935af2b33488db1eb3a6 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98670 Analysis date: Sun, 18 Oct 2026 23:58:55 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: An incorrect devres teardown order can let the Xilinx Zynq XADC IRQ handler requeue delayed work that executes after its driver state is freed, causing a host-admin-triggered use-after-free and potential kernel crash. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98670 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98670 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-98670 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98670 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC TEMP_DISTANCE_MERGE=LOW->MODERATE;AEGIS=MODERATE_KPANIC;GAP=2 (final reconciliation agrees; DECISION: both MODERATE_KPANIC) 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-416;CWE-362;*CWE-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'An incorrect devres teardown order in the Xilinx Zynq XADC driver can allow the alarm IRQ handler to queue zynq_unmask_work after the delayed work was already cancelled. The queued worker may then run after the containing xadc structure has been freed, creating a use-after-free condition. The most direct impact is a kernel crash and local denial of service. Reuse of the freed work item memory may also create a potential path to kernel memory corruption or privilege escalation, although a reliable controlled write primitive is not established by the available code. For the CVSS the PR:H reflects that driver unbind or device removal normally requires administrative control on the host. AC:H reflects the narrow race window between work cancellation and IRQ release. The issue is not network reachable and requires affected Xilinx Zynq XADC hardware with the relevant interrupt path active. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to MODERATE_KPANIC because 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 TEMP_DISTANCE_MERGE and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.2 and ActionableScore 0 with primitive class CLASS_B and manual review RECOMMENDED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE SIMPLEFIX DMAorINTERRUPT LINUS TEMP_DISTANCE_MERGE KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=YES NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 1. * Conservative score: 1. * Raw paranoid score: 1. * Paranoid score: 1. * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +2 Real UAF. The IRQ handler can requeue an embedded delayed-work object after cancellation, allowing the worker to execute after the containing XADC state has been freed. * +1 Realistic kernel crash or strong DoS. Executing delayed work through freed driver state can produce an invalid dereference or other fatal kernel fault. * -2 Proven host-administrator requirement. The described complete trigger depends on unbinding or removing the host platform driver, which is a host device-management operation. * No race penalty. The vulnerable interrupt must occur during teardown, but the supplied evidence does not establish that the timing is sufficiently improbable or uncontrollable for a separate deduction. * No hardware penalty. Xilinx Zynq XADC hardware is required, but the evidence does not independently establish a physical attacker requirement or justify treating every affected deployment as rare. * Controlled reclaim, attacker-shaped replacement data, arbitrary read or write, callback control, disclosure, and privilege escalation are not demonstrated. * Structured stale-object leverage is not awarded. The stale object is structured, but the shown use is a constrained asynchronous teardown path with no demonstrated exploitation-relevant field consumption after reuse. * No extra availability point is awarded for the same possible kernel crash. * No repeated release or refcount mutation exists. The bug is post-free worker execution, not a second put, free, or refcount operation. * NEW52 B5-R does not apply because no retry-accumulated heap OOB write exists. * NEW53 B3-PENDING does not apply because no shared-backing write exists. * V33 and V32 do not apply because there is no attacker-influenced active networking metadata corruption or privileged downstream packet consumer. * B4-PENDING does not apply because no authorization decision or DENY-to-ALLOW transition is involved. 3. Reachability analysis The complete documented trigger is driver unbind or equivalent host-controlled device removal while the XADC alarm IRQ remains capable of firing. Such platform-device management is controlled by host administration rather than an ordinary user, delegated namespace capability, or network input. The operation is not namespace scoped, and no attacker-accessible userspace interface that can independently perform the complete teardown is established. Affected Xilinx Zynq XADC hardware, an active IRQ, and the vulnerable driver are prerequisites. The interrupt must arrive after delayed-work cancellation but before IRQ release. The attacker does not have demonstrated control over both teardown and IRQ timing below host-admin privilege. 4. Primitive and severity interpretation The exact primitive is asynchronous use after free of delayed work embedded in the freed XADC driver state. This is a real CLASS_B lifetime violation. Although the XADC state is a structured object, the demonstrated path is a fixed post-teardown worker rather than attacker-controlled replacement of an active object. The supported consequence is kernel crash or local denial of service. Memory corruption or privilege escalation remains theoretical because controlled reclaim, useful stale-field consumption, and an attacker-directed write are not established. ImportantCandidate is NO because the complete trigger is host-admin gated and the UAF is constrained to teardown without meaningful demonstrated reuse leverage. AutoDowngradeAllowed is YES because no unresolved authorization, ownership, cross-boundary, repeated-lifetime, or controlled-corruption primitive remains. 5. One-sentence report phrase An incorrect devres teardown order can let the Xilinx Zynq XADC IRQ handler requeue delayed work that executes after its driver state is freed, causing a host-admin-triggered use-after-free and potential kernel crash. 6. Manual review recommendation MANUAL CHECK RECOMMENDED The UAF is concrete, but the currently supported attack model is a privileged and constrained device-unbind race without an independently useful exploitation primitive. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: iio: adc: xilinx-xadc: free IRQ before cancelling the unmask worker on unbind Commit: a29d385ad7b340c952a3935af2b33488db1eb3a6 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a29d385ad7b340c952a3935af2b33488db1eb3a6 Commit description: The ZYNQ XADC alarm IRQ handler queues zynq_unmask_work via schedule_delayed_work(); that work is cleared by a devm callback. Register the devm callback before devm_request_irq() so the devres LIFO teardown frees the IRQ first, ensuring the handler can no longer queue work by the time the workqueue is cleared. Otherwise the handler could re-arm the work and run it after the xadc structure has been freed. This issue was found by an in-house static analysis tool. Fixes: 2a9685d ("iio: adc: xilinx: use more devres helpers and remove remove()") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6 Reviewed-by: David Lechner Signed-off-by: Fan Wu Reviewed-by: Sai Krishna Potthuri Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman Changed files: drivers/iio/adc/xilinx-xadc-core.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=a29d385ad7b340c952a3935af2b33488db1eb3a6 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98670 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98670 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: 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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).