From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98397][MODERATE REGULAR] platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown [ Upstream Date: Wed, 14 Oct 2026 22:48:08 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98397 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: c62b6e081119f2ab03cfcafde1f83c0f50e8e726 List-Id: CVE: CVE-2026-98397 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown [ Upstream Commit: c62b6e081119f2ab03cfcafde1f83c0f50e8e726 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c62b6e081119f2ab03cfcafde1f83c0f50e8e726 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98397 Analysis date: Wed, 14 Oct 2026 22:48:08 -0400 ActionableScore: 2 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-2026-98397 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98397 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-98397 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98397 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, Aegis: 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-672;CWE-825;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.4';DESCR 'A device lifetime error in x86 android tablets can leave a deferred devres action holding a stale struct device pointer. The reference returned by acpi_bus_find_device_by_name is dropped at the end of the initialization loop, while gpio_secondary_unset may later call set_secondary_fwnode on the same device during driver teardown. If the device is released in the interval, this becomes a use after free and can cause a kernel crash or memory corruption. For the CVSS the PR:H is selected because reliable triggering normally requires control over driver unbind, device removal, or platform driver teardown operations. AC:H reflects the required lifetime ordering between device release and the deferred callback. The issue is local and is not directly network reachable. Impact is at least denial of service and the stale object update creates a plausible confidentiality and integrity risk in the paranoid interpretation. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 6.4 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold 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 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4. The independent weaker Aegis shadow evaluated CVSS 2.1 and ActionableScore 4 with primitive class CLASS_B and manual review RECOMMENDED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE UAF HARDWARE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw conservative score: 2 * Conservative score: 2 * Raw paranoid score: 2 * Paranoid score: 2 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown Positive signals: * +2 Real UAF. The reference obtained by `acpi_bus_find_device_by_name()` can be dropped while the deferred devres action retains the same `struct device` pointer. * +1 Constrained post-lifetime write. `gpio_secondary_unset()` passes the stale pointer to `set_secondary_fwnode(dev, NULL)`, which modifies fixed device state. The value and target field are not meaningfully attacker-controlled. * +1 Realistic kernel crash. Accessing and modifying a released `struct device` can produce an Oops or other fatal kernel fault. Negative signals: * -2 Rare hardware-specific path. The affected driver is limited to particular x86 Android tablet platform configurations, including the identified Lenovo tablet families. Important non-awarded signals: * No controlled reclaim, replacement object, arbitrary write, callback control, disclosure, or LPE is demonstrated. * Structured stale-object leverage is not awarded because the stale operation is a fixed teardown callback and attacker influence over replacement contents is absent. * No repeated release/refcount signal applies. The original `put_device()` can end the lifetime, but the vulnerable callback does not perform a second `put_device()` in the unpatched code. It performs `set_secondary_fwnode()` instead. * Paranoid repeated-refcount leverage is therefore withheld. * FLOOR 5 is not applicable. * Extra availability, confidentiality, and integrity points are not awarded. * B5-R, B3-PENDING, and B4-PENDING do not apply. 3. Reachability analysis The vulnerable operation occurs during teardown of the parent platform driver after the referenced secondary device may already have been released. Driver unbind or module removal ordinarily involves host device-management authority, but the supplied code does not establish the complete sequence that releases the secondary device and invokes the parent devres callback. `HostAdminRequired` is therefore `UNKNOWN`, and no privilege penalty is applied. No user-namespace or network-namespace interface governs this platform-device lifetime sequence. There is no remote trigger. An affected x86 Android tablet platform and its ACPI-described devices are prerequisites. The commit describes an ordering window, but it does not establish a narrow attacker-driven race, so no timing penalty is applied. 4. Primitive and severity interpretation The exact primitive is a real cleanup-time UAF involving an active `struct device`. A borrowed pointer survives after its only held reference is dropped, and a later devres callback uses that pointer to clear the secondary firmware node. This is an ordinary stale cleanup dereference with a constrained state modification, not a repeated lifetime/refcount mutation. The patch adds a new balanced `get_device()` and `put_device()` pair. The added `put_device()` is correct ownership cleanup and is not evidence that the vulnerable version performed a double release. The issue is `CLASS_B` because an actual lifetime violation and post-lifetime object use are established. The supported consequence is kernel crash or constrained corruption of the stale device object. Strong exploitation leverage beyond that crash is not established. `ImportantCandidate=NO` because the path is hardware-specific, teardown-oriented, and lacks controlled reuse or another independently useful corruption primitive. `AutoDowngradeAllowed=YES` because this is a constrained Class B cleanup UAF without repeated refcount mutation or unresolved security-boundary leverage. 5. One-sentence report phrase A missing device reference can leave a deferred x86 Android tablet teardown callback using and modifying a released struct device, causing a constrained local use after free and possible kernel crash. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm the actual device-release and parent-teardown call sequence, but current evidence supports a constrained hardware-specific cleanup UAF rather than an Important-grade exploitation primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown [ Upstream Commit: c62b6e081119f2ab03cfcafde1f83c0f50e8e726 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c62b6e081119f2ab03cfcafde1f83c0f50e8e726 Changed files: drivers/platform/x86/x86-android-tablets/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=c62b6e081119f2ab03cfcafde1f83c0f50e8e726 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98397 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98397 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:L/I:L/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: 2 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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).