From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99209][MODERATE REGULAR] drm/xe: skip eviction of a BO with no resource [ Upstream Date: Fri, 30 Oct 2026 12:18:30 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99209 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: 1 X-AL-KERNEL-Commit: 6046bb9cb2859e3d9bf939e4d6527f3827e1096f List-Id: CVE: CVE-2026-99209 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/xe: skip eviction of a BO with no resource [ Upstream Commit: 6046bb9cb2859e3d9bf939e4d6527f3827e1096f Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6046bb9cb2859e3d9bf939e4d6527f3827e1096f Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99209 Analysis date: Fri, 30 Oct 2026 12:18:30 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A resource-less imported Xe dma-buf can reach eviction and cause a kernel NULL-pointer dereference in `xe_evict_flags()`, with no demonstrated memory-corruption or authorization primitive. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99209 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99209 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-2026-99209 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-99209 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final 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:L/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;*CWE-20;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A state validation bug in drm xe allows xe_evict_flags to dereference tbo resource when an imported dma-buf BO has already lost its TTM resource while its attachment remains live. Exporter invalidation can then reach xe_dma_buf_move_notify and xe_bo_evict and cause a kernel NULL pointer dereference and host kernel crash. For the CVSS the PR:L value is selected because triggering requires a local user or process able to access the Xe GPU and construct or import dma-buf objects. The demonstrated primitive is an invalid read through NULL rather than UAF or writable memory corruption, so confidentiality and integrity remain N while availability is H. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 2 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. 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 V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 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 MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE NULLPTR LEAK UAF HARDWARE MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1. * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 2. * Paranoid score: 2; no floor or cap applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * Base +1 — reliable kernel crash/strong DoS: `xe_evict_flags()` dereferences `tbo->resource->mem_type` when `resource == NULL`; the supplied stack confirms a kernel NULL-pointer fault. * Paranoid +1 — plausible local below-host-admin trigger: the supplied triage describes a local process with Xe GPU access constructing/importing dma-buf objects. The patch itself does not establish render-node permissions or the complete userspace-triggerable invalidation sequence, so this is excluded from the conservative score. * No UAF, OOB access, write, stale-object consumption, 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 structured state. * No extra availability point: the NULL dereference and resulting crash are the same effect. * No hardware penalty: Xe hardware is required, but the evidence does not establish rare or physical-attacker-only hardware. 3. Reachability analysis The demonstrated path is imported dma-buf teardown/invalidation through `xe_dma_buf_move_notify()` to `xe_bo_evict()`. A local GPU client may plausibly reach it, but the supplied source does not prove which DRM node is sufficient, whether an ordinary logged-in/render-node user controls the complete resource-loss and move-notify sequence, or whether compositor, DRM-master, delegated service, or administrator participation is required. Therefore host-administrator and namespace privilege requirements remain unknown. No race or special timing requirement is demonstrated. 4. Primitive and severity reading The exact primitive is a NULL-based invalid read at `tbo->resource->mem_type`, producing an immediate fault. It is neither an active structured-state corruption nor a fixed-storage UAF. The patch adds a state guard and selects the existing empty-placement path. This is CLASS_C with availability impact only; no useful leverage remains after excluding the crash. Important candidacy is therefore unsupported, and ordinary downgrade remains permissible. 5. One-sentence report phrase A resource-less imported Xe dma-buf can reach eviction and cause a kernel NULL-pointer dereference in `xe_evict_flags()`, with no demonstrated memory-corruption or authorization primitive. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm whether an ordinary render-node client can drive the complete teardown and exporter-invalidation sequence. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/xe: skip eviction of a BO with no resource [ Upstream Commit: 6046bb9cb2859e3d9bf939e4d6527f3827e1096f Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6046bb9cb2859e3d9bf939e4d6527f3827e1096f Changed files: drivers/gpu/drm/xe/xe_bo.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=6046bb9cb2859e3d9bf939e4d6527f3827e1096f ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99209 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99209 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:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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: 1 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).