From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98946][LOW] drm/vc4: Disable the V3D interrupt across runtime suspend [ Upstream Date: Mon, 26 Oct 2026 16:42:27 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98946 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: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: e81402c3d42041356cb7978510ebab997bc8d411 List-Id: CVE: CVE-2026-98946 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/vc4: Disable the V3D interrupt across runtime suspend [ Upstream Commit: e81402c3d42041356cb7978510ebab997bc8d411 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e81402c3d42041356cb7978510ebab997bc8d411 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98946 Analysis date: Mon, 26 Oct 2026 16:42:27 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A narrow ARMCTRL interrupt/runtime-suspend race can process bogus powered-off V3D status and reschedule cancelled overflow work, with only device availability impact supported. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98946 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98946 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-2026-98946 LOW https://www.kernelcve.org/list/?q=CVE-2026-98946 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) 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-362;CWE-667;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'This is a race between VC4 interrupt dispatch and V3D runtime suspend on RPi 0-3 systems using the ARMCTRL interrupt controller. A CPU may acknowledge a pending interrupt without becoming visible to synchronize_irq, allowing vc4_irq to run after the V3D power domain is off. Register reads then return 0xdeadbeef and can falsely indicate FLDONE, FRDONE and OUTOMEM. The job completion paths avoid a NULL pointer dereference when no job exists, but OUTOMEM can schedule overflow_mem_work after it was already cancelled. No UAF, OOB access, information disclosure, or controlled memory write is demonstrated. For the CVSS the PR:L value reflects the need for a local user or process able to exercise the VC4 DRM interface and runtime power transitions. AC:H reflects the narrow interrupt timing window. The issue is not directly network reachable and primarily threatens GPU availability. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and 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 DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE DANGER NULLPTR DMAorINTERRUPT HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 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 base score: 0 (+1 plausible device/GPU availability impact, -1 narrow hardware interrupt race). * Conservative score: 0. No floor or cap applied. * Raw paranoid score: 0. The evidence does not support an additional host-crash or corruption point. * Paranoid score: 0. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Availability impact plausible: a late VC4 interrupt can interpret powered-off register reads as `0xdeadbeef` and reschedule `overflow_mem_work` after cancellation, threatening correct GPU/runtime-PM operation. * -1 Hard timing requirement: the CPU must acknowledge the ARMCTRL interrupt but not reach `handle_level_irq()` before runtime suspend passes `synchronize_irq()`. * No reliable kernel-crash point: the commit explicitly says job handlers avoid NULL dereferences, and it does not demonstrate panic or host-wide failure. * No UAF, OOB write, repeated release, controlled corruption, disclosure, or authorization bypass is shown. * NEW52/B5-R does not apply: there is no heap OOB write, retry-accumulated index, or later consumption of corrupted heap state. * No extra availability point: GPU disruption and the late work item are the same potential consequence. 3. Reachability analysis The affected environment is RPi 0–3 using ARMCTRL and VC4 runtime suspend. The supplied summary suggests a local DRM actor may influence rendering and power transitions, but the patch does not establish which render-node, DRM-master, compositor, or administrator credentials can drive the complete race. Therefore host-admin and namespace reachability remain unknown. No network path, namespace capability path, special prior delegation, or normal-user complete trigger is proven. 4. Primitive and severity reading The primitive is a synchronization failure: `synchronize_irq()` cannot observe one ARMCTRL dispatch state, allowing an interrupt handler to execute after V3D power-off and schedule work after cancellation. This is invalid-state/device-availability behavior, classified CLASS_C. There is no stale freed object, heap overwrite, active structured-state corruption, or demonstrated cross-boundary consumer. Stronger effects such as kernel panic, memory corruption, or privilege escalation are unsupported. Important-candidate preservation is therefore unwarranted, and automatic Moderate/Low-like handling is allowed. 5. One-sentence report phrase A narrow ARMCTRL interrupt/runtime-suspend race can process bogus powered-off V3D status and reschedule cancelled overflow work, with only device availability impact supported. 6. Manual review advice NO MANUAL CHECK NEEDED The patch shows a hardware-specific quiescing defect without a material corruption, lifetime, authorization, or trust-boundary primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/vc4: Disable the V3D interrupt across runtime suspend [ Upstream Commit: e81402c3d42041356cb7978510ebab997bc8d411 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e81402c3d42041356cb7978510ebab997bc8d411 Changed files: drivers/gpu/drm/vc4/vc4_irq.c drivers/gpu/drm/vc4/vc4_v3d.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=e81402c3d42041356cb7978510ebab997bc8d411 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98946 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98946 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:L/UI:N/S:U/C:N/I:N/A:L 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: 0 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).