From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98391][LOW] drm/xe: Guard page-fault worker with runtime PM check [ Upstream Date: Wed, 14 Oct 2026 22:09:03 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98391 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: 0 X-AL-KERNEL-Commit: 25764620ec64c0142e2c87c41787f45540cf09ff List-Id: CVE: CVE-2026-98391 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/xe: Guard page-fault worker with runtime PM check [ Upstream Commit: 25764620ec64c0142e2c87c41787f45540cf09ff Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25764620ec64c0142e2c87c41787f45540cf09ff Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98391 Analysis date: Wed, 14 Oct 2026 22:09:03 -0400 ActionableScore: 1 ActionableScore lower bound: 0 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-2026-98391 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98391 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-2026-98391 LOW https://www.kernelcve.org/list/?q=CVE-2026-98391 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=LOW RESULT=DIFF (independent Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE) 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-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race between VM teardown, queued page fault processing, and runtime autosuspend can let the Xe page fault worker acknowledge stale faults after the GPU has already entered the suspended state. The demonstrated result is an assertion and kernel WARNING during GuC CT access. Autosuspend in the middle of an acknowledgement batch may also skip the final flush and desynchronize the CT cadence, which can plausibly cause a GPU hang or driver availability failure. For the CVSS the PR:L value is used because a local process with access to the GPU render interface may be able to create GPU contexts, generate page faults, and tear down the owning VM without administrative privileges. AC:H is used because successful triggering depends on a race between asynchronous VM teardown, stale queued faults, and device autosuspend. The issue is not network reachable. The supported impact is denial of service or GPU disruption. No UAF, OOB access, arbitrary write, information leak, or credible privilege escalation primitive is established by the analyzed code. 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. Recorded rule transitions were final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic. 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 KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 1.5 and ActionableScore 0 with primitive class CLASS_C and manual review NO. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE INIT WARNONLY HARDWARE KPANIC_UNSUPPORTED_REMOVED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 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 conservative score: 0. * Conservative score: 0. No floor or cap applied. * Raw paranoid score: 1. * Paranoid score: 1. No floor or cap applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown Conservative signals: * +0 WARN and invalid power-state access. The demonstrated consequence is an assertion and kernel WARNING, not a panic, memory corruption, or confirmed GPU hang. * No negative points. The race is not proven sufficiently narrow or uncontrollable for a timing penalty. Intel Xe hardware is not inherently rare. Paranoid signals: * +1 Availability impact. Autosuspend during an acknowledgement batch can leave write-only acknowledgements without the final CT flush and desynchronize cadence tracking, creating a technically plausible GPU or driver hang. Material non-awarded signals: * No UAF. Stale page-fault entries refer to a dead VM context, but the shown worker accesses a suspended device rather than dereferencing freed VM storage. * No OOB read or write, controlled reclaim, arbitrary write, repeated release, or refcount mutation is established. * No extra crash point was awarded because only a WARNING is demonstrated. * No confidentiality, integrity, LPE, authorization-bypass, or remote-reachability signal is established. * B5-R does not apply because no retry-accumulated heap OOB write exists. * B3-PENDING does not apply because no shared-backing write exists. * B4-PENDING does not apply because there is no DENY-to-ALLOW authorization change. 3. Reachability analysis The likely trigger involves creating GPU work that generates page faults, tearing down the owning VM or execution queue, and allowing runtime autosuspend before the queued faults are acknowledged. Xe render-node clients commonly create GPU contexts, but the supplied call path does not positively establish that an ordinary logged-in user can drive the complete fault, teardown, and autosuspend sequence. Therefore HostAdminRequired and NamespaceScopedPrivilege remain UNKNOWN, with no privilege penalty or unprivileged-trigger bonus. This is not a KMS display-control path, and DRM master or compositor authority is not directly implicated. No network trigger exists. Intel Xe hardware and runtime PM are prerequisites, but the hardware is not shown to be rare or physical-attacker controlled. Race repeatability is unresolved, so no hard-race penalty is applied. 4. Primitive and severity interpretation The exact defect is a runtime-PM synchronization race. VM teardown can drop the PM reference while stale fault acknowledgements remain queued, permitting the worker to access GuC CT state after device suspension. This is invalid active-state consumption, not a real post-lifetime object use. The stale fault descriptor is processed after its owning context has disappeared, but no freed VM object is shown to be dereferenced and no lifetime-mutating operation is performed through a dangling reference. It is therefore CLASS_C rather than CLASS_B. The demonstrated result is a WARNING. The stronger patch-supported possibility is device-local availability loss from an incomplete acknowledgement batch and CT cadence desynchronization. Host-wide panic, memory corruption, privilege escalation, and a security-boundary bypass remain unsupported. ImportantCandidate is NO because no independently useful corruption or boundary primitive exists. AutoDowngradeAllowed is YES because the issue is a constrained invalid-state and availability defect. Manual review is still recommended to verify render-node reachability and whether CT desynchronization can reliably hang the GPU or host driver. 5. One-sentence report phrase A runtime PM race can make the Xe page-fault worker acknowledge stale faults on a suspended GPU, causing a warning and potentially an incomplete GuC CT batch with device-level availability loss. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm whether an ordinary render-node client can drive the complete race and whether the CT cadence desynchronization produces a reproducible GPU hang rather than only a warning. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/xe: Guard page-fault worker with runtime PM check [ Upstream Commit: 25764620ec64c0142e2c87c41787f45540cf09ff Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25764620ec64c0142e2c87c41787f45540cf09ff Changed files: drivers/gpu/drm/xe/xe_pagefault.c drivers/gpu/drm/xe/xe_pagefault_types.h 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=25764620ec64c0142e2c87c41787f45540cf09ff ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98391 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98391 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: 0 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).