From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98165][LOW] drm/amdgpu: restrict BAR0 fallback read to SR-IOV VFs only Date: Tue, 06 Oct 2026 13:49:38 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98165 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: 5612934c255ad9352d07181f14981cfabd7b7a95 List-Id: CVE: CVE-2026-98165 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/amdgpu: restrict BAR0 fallback read to SR-IOV VFs only Commit: 5612934c255ad9352d07181f14981cfabd7b7a95 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5612934c255ad9352d07181f14981cfabd7b7a95 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98165 Analysis date: Tue, 06 Oct 2026 13:49:38 -0400 ActionableScore: 0 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-2026-98165 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98165 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-2026-98165 LOW https://www.kernelcve.org/list/?q=CVE-2026-98165 CHECK WITH IMPACT FROM ORIG NN 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-20;CWE-754;CWE-670;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'The AMDGPU framebuffer fallback path could read through PCI BAR0 on physical functions and ordinary non SR IOV devices even though this workaround was intended only for SR IOV virtual functions without an available VRAM aperture during early initialization. On a non VF device BAR0 can expose MMIO resources with different semantics, so using it as a framebuffer source may return invalid data or cause GPU initialization failures, GPU hangs, or host availability degradation. No direct memory corruption, information disclosure, or write primitive is established by the available code. For the CVSS the PR:L value is used for the paranoid score because a user with delegated GPU access might be able to provoke a recovery or reinitialization path, although reliable triggering normally appears to require administrative control over driver probing or device reset. The issue is not network reachable. The supported impact is denial of service, while privilege escalation is not supported by a concrete primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE READ SIMPLEFIX HARDWARE DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 0 * Conservative score: 0 * Raw paranoid score: 0 * Paranoid score: 0 * No floor or cap applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +0 Weak invalid-access concern. The fallback can read PCI BAR0 on a non-VF device where BAR0 may have different MMIO semantics, but no OOB access, UAF, overwrite, disclosure, or concrete host corruption is established. * +0 Device-local failure. Initialization failure or a GPU hang is plausible, but the supplied patch does not establish a kernel panic or host-wide fatal DoS. * No remote-reachability point. The operation occurs during local AMDGPU initialization. * No local-unprivileged point. The complete trigger is not shown to be reachable by an ordinary user or delegated graphics client. * No corruption or exploitation-leverage point. Controlled payload, target selection, reclaim, lifetime corruption, DMA corruption, and arbitrary read or write are not demonstrated. * No C or I points. BAR0 data is not shown to reach userspace or alter protected kernel state. * No hardware rarity penalty. AMD GPUs are not inherently rare, but the affected early-initialization path is also not broad exposure. * No privilege penalty. Host-admin control appears plausible for driver probing or reset, but it is not positively established for the complete trigger. 3. Reachability analysis The path is an early AMDGPU framebuffer-read fallback originally intended for SR-IOV VFs. The supplied context does not show that an ordinary logged-in user, DRM render-node client, DRM master, compositor, or delegated display service can invoke the complete vulnerable operation. Driver probing, binding, and early initialization are generally controlled by the host, but the evidence is insufficient to mark host-admin privilege as definitively required. The operation concerns a physical PCI device and is not namespace-scoped. No network trigger, attacker-created object, race, special boot option, or firmware-compromise prerequisite is established. 4. Primitive and severity interpretation The exact defect is an insufficient mode check that permits an SR-IOV-specific BAR0 read fallback to run on non-VF devices. This is a logic and device-state validation error, classified as CLASS_C because the strongest supported outcome is invalid MMIO behavior or device initialization failure. There is no stale object, lifetime violation, repeated release, active-state retirement bypass, controlled semantic reinterpretation, or security-boundary bypass. A GPU hang is plausible, while host-wide denial of service remains unproven. Privilege escalation and confidentiality or integrity effects would require unsupported additional primitives. ImportantCandidate is NO because no Important-preserving primitive exists. AutoDowngradeAllowed is YES because the evidence supports a constrained device-initialization issue without unresolved kernel corruption or boundary-crossing leverage. 5. One-sentence report phrase The AMDGPU BAR0 framebuffer fallback could run on non SR IOV devices and perform an inappropriate MMIO read, but the available evidence supports only a constrained device initialization or availability issue without kernel memory corruption or privilege escalation. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch is a narrow validation restriction, and no UAF, overwrite, disclosure, host-wide crash, or security-boundary primitive is established. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amdgpu: restrict BAR0 fallback read to SR-IOV VFs only Commit: 5612934c255ad9352d07181f14981cfabd7b7a95 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5612934c255ad9352d07181f14981cfabd7b7a95 Commit description: The BAR0 fallback read path was introduced as a workaround for SR-IOV VFs where the VRAM aperture is not available during early init. Restrict this workaround to only SR-IOV VFs where it's needed. Reported-by: gloveless@jqluv.com Fixes: cba4928 ("drm/amdgpu: reduce early full GPU access during SR-IOV init") Acked-by: Alex Deucher Link: https://patch.msgid.link/20260826185102.2269511-1-mario.limonciello@amd.com Signed-off-by: Mario Limonciello Signed-off-by: Alex Deucher (cherry picked from commit d8a0aff ) Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/amdgpu/amdgpu_device.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=5612934c255ad9352d07181f14981cfabd7b7a95 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98165 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98165 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: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).