From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98854][LOW] of/overlay: only treat a positive changeset id as registered Date: Sun, 18 Oct 2026 23:51:20 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98854 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: c08a54df9d33dcd6ff089adc9434b2c008af3a39 List-Id: CVE: CVE-2026-98854 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: of/overlay: only treat a positive changeset id as registered Commit: c08a54df9d33dcd6ff089adc9434b2c008af3a39 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c08a54df9d33dcd6ff089adc9434b2c008af3a39 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98854 Analysis date: Sun, 18 Oct 2026 23:51:20 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A negative idr_alloc error is mistaken for a registered Device Tree overlay ID, causing cleanup to execute list_del on an uninitialized list entry and potentially trigger a kernel NULL pointer dereference. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98854 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98854 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-2026-98854 LOW https://www.kernelcve.org/list/?q=CVE-2026-98854 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A logic error in the Device Tree overlay cleanup path treats a negative idr_alloc() error as a registered changeset. The subsequent cleanup calls idr_remove() with a negative identifier and executes list_del() on ovcs_list before that list entry has been initialized, resulting in a NULL pointer dereference and a possible kernel crash. Triggering requires a local ability to request Device Tree overlay application together with an idr_alloc() failure, so attack complexity is high and the issue is not directly network reachable. For the CVSS the PR:L value is used for the paranoid score because some deployments may delegate overlay management to a restricted service account, container root, or another reduced capability administrative context. The realistic base assessment uses PR:H because direct Device Tree overlay management is normally restricted to a host administrator. Impact is denial of service only because the affected list pointers are expected to be NULL and the analyzed path does not expose a UAF, OOB access, information leak, or attacker controlled write primitive. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. The independent weaker Aegis shadow evaluated CVSS 4.1 and ActionableScore 1 with primitive class CLASS_C and manual review NO. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE SIMPLEFIX ERRORPATH IMPROVEONLY LINUS - - 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 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 * +1 Reliable kernel fault or DoS. If `idr_alloc()` fails, the negative ID passes the nonzero test and `list_del()` operates on an uninitialized list entry, producing the documented NULL-pointer dereference. * +0 Weak corruption concern. The affected list pointers are expected to be NULL, so the operation faults without establishing an attacker-controlled write or useful corrupted state. * +0 Additional availability. The same NULL dereference is not counted again. * No privilege penalty was applied because the complete attacker-accessible call path is not supplied and host-administrator privilege is not positively established. * No race penalty was applied. This is an ordered allocation-error cleanup path, not a timing race. * No UAF, OOB access, double release, controlled reclaim, authorization bypass, information disclosure, or privilege-escalation primitive is established. * B5-R does not apply because there is no retry-accumulated heap OOB write. * B3-PENDING does not apply because there is no shared-backing write. * V33 and V34 do not apply because no attacker-influenced active structured state is corrupted and consumed across a trust boundary. * B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW. ## 3. Reachability analysis The immediate failure requires `of_overlay_fdt_apply()` to reach an `idr_alloc()` failure. The supplied material does not establish a direct ordinary-user interface, a namespace-scoped capability path, or attacker control sufficient to force that allocation failure. Device Tree overlay management commonly involves privileged platform or management components, but that deployment expectation is insufficient to set `HostAdminRequired=YES`. Conversely, theoretical delegation to a service account or container does not prove below-host-admin reachability. There is no direct network trigger, special race, or demonstrated namespace path. ## 4. Primitive and severity interpretation The exact primitive is an invalid cleanup operation on a partially initialized object. A negative error value is mistaken for a registered ID, after which `list_del()` receives an uninitialized list node and dereferences NULL. This is Class C crash or invalid-state behavior. It is not a real UAF because no object is shown to have ended its lifetime before use. It is not a repeated release or refcount mutation, and no active replacement state survives for later privileged consumption. The demonstrated consequence is an Oops or possible panic. Stronger confidentiality, integrity, LPE, or cross-boundary consequences are unsupported. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` because the failure is a deterministic NULL dereference with no independently useful corruption primitive. ## 5. One-sentence report phrase A negative idr_alloc error is mistaken for a registered Device Tree overlay ID, causing cleanup to execute list_del on an uninitialized list entry and potentially trigger a kernel NULL pointer dereference. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch establishes a constrained NULL-dereference path without UAF, OOB write, authorization bypass, active-state corruption, or unresolved trust-boundary impact. ## 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: of/overlay: only treat a positive changeset id as registered Commit: c08a54df9d33dcd6ff089adc9434b2c008af3a39 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c08a54df9d33dcd6ff089adc9434b2c008af3a39 Commit description: of_overlay_fdt_apply() stores the idr_alloc() return value in ovcs->id before checking it. On failure the stored id is negative, free_overlay_changeset()'s "if (ovcs->id)" check passes, idr_remove() is called with a negative id and list_del() runs on ovcs->ovcs_list, which is not initialized until after the id allocation. An allocation failure at that point dereferences NULL. Make free_overlay_changeset() treat only a strict-positive id as registered. The rest of the function already copes with a partially-initialized ovcs, so the error path stays a plain goto err_free_ovcs. Fixes: 61b4de4 ("of: overlay: minor restructuring") Cc: stable@vger.kernel.org Suggested-by: Geert Uytterhoeven Assisted-by: Claude:claude-fable-5 [Claude Code] Reviewed-by: Geert Uytterhoeven Signed-off-by: Abdurrahman Hussain Link: https://patch.msgid.link/20260831-nh-of-alias-overlay-v7-5-02754604805a@nexthop.ai Signed-off-by: Rob Herring (Arm) Signed-off-by: Greg Kroah-Hartman Changed files: drivers/of/overlay.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=c08a54df9d33dcd6ff089adc9434b2c008af3a39 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98854 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98854 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:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 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 alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).