From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68266][MODERATE 7.0] drm/xe: Hold a dma-buf reference for imported BOs [ Upstream Date: Mon, 10 Aug 2026 11:48:21 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68266 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 7 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: c22d65d62b3318e237c0e5b1177d90ab83d9fe06 List-Id: CVE: CVE-2026-68266 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: drm/xe: Hold a dma-buf reference for imported BOs [ Upstream Commit: c22d65d62b3318e237c0e5b1177d90ab83d9fe06 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c22d65d62b3318e237c0e5b1177d90ab83d9fe06 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68266 Analysis date: Mon, 10 Aug 2026 11:48:21 -0400 ActionableScore: 7 ActionableScore lower bound: 4 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A local use-after-free in the drm xe dma-buf import path can leave an imported BO referencing a freed exporter reservation object, causing a kernel crash and requiring manual review for possible privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68266 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68266 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 7.0 Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-68266 MODERATE CHECK WITH IMPACT FROM ORIG NN 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:H/I:H/A:H';*CWE-416;*CWE-664;*CWE-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use after free can occur in the drm xe dma-buf import path because an imported sg BO may keep bo base resv pointing to the exporter dma_buf resv without holding a dma-buf lifetime reference. If dma_buf_dynamic_attach fails or ttm_bo_init_reserved fails during BO creation, the BO can later be destroyed asynchronously by ttm_bo_delayed_delete while the exporter reservation object has already been freed. This is a local kernel memory lifetime bug and can trigger a general protection fault or kernel crash when the stale reservation object is locked. For the CVSS the PR:L is used because a local user process with access to the DRM GPU device or render node can potentially exercise dma-buf import paths without full administrator privileges. The issue is not network reachable. Impact is at least local denial of service via kernel crash. For the paranoid score, choose the highest still defensible interpretation supported by the bug class and patch context, with preference for manual-review sensitivity over autoclosed false negatives. Because the primitive is a kernel UAF rather than a pure NULL dereference or resource leak, worst case impact may include confidentiality and integrity compromise if freed memory can be reclaimed in a controlled way.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6) YES OOB INIT UAF DMAorINTERRUPT HARDWARE KPANIC MEMORY YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=7 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 7 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Local unprivileged trigger: +1. DRM render nodes are commonly accessible to local users in desktop and GPU compute setups. * Memory corruption, strong corruption primitive: +2. The commit explicitly describes a use-after-free of the exporter dma_buf reservation object. * Real lifetime corruption: +1. The bug is caused by missing dma-buf lifetime reference management for imported BOs. * Reliable kernel crash / strong DoS: +1. The commit includes an observed general protection fault in ttm_bo_delayed_delete. * Hard or unreliable timing / error-path condition: -1. Triggering depends on failure paths such as dma_buf_dynamic_attach failure or ttm_bo_init_reserved failure and asynchronous BO destruction. * Constrained primitive / no demonstrated reclaim: -1. The observed access is stale dma_resv locking, with no shown attacker-controlled reclaim, overwrite, callback dispatch, or arbitrary write. Paranoid additional signals: * Weak LPE concern: +1. A kernel UAF in a DRM dma-buf lifetime path may deserve manual LPE review even though no reclaim primitive is demonstrated. * Confidentiality impact plausible: +1. Only for paranoid scoring, if freed memory can be reclaimed or interpreted as another object. * Integrity impact plausible: +1. Only for paranoid scoring, because stale synchronization object use may become more than a crash if object reuse is controllable. * Local device-object lifetime control relevance: +1. The affected path involves dma-buf import and BO lifetime ownership, where local users may influence object creation, failure, and destruction ordering. ## 3. Reachability analysis The bug is local, not network reachable. A likely trigger requires a local process that can access the DRM xe device or render node and exercise dma-buf import paths. In typical desktop or GPU compute deployments, render node access may be granted to non-root users through group or seat permissions, so PR:L is more realistic than PR:H for triage. In containers, reachability depends on whether the host DRM device is passed through. The path is not universal because it requires Intel xe driver usage and imported dma-buf BOs, but this is still a normal GPU userspace interface rather than a rare debug-only path. ## 4. Severity interpretation This is more than an ordinary Moderate because the patch fixes an explicit kernel use-after-free in an asynchronous TTM destruction path. The demonstrated realistic impact is local DoS via kernel crash. The theoretical higher impact is possible privilege escalation from UAF object reuse, but the patch does not show attacker-controlled reclaim, overwrite, type confusion, callback control, or arbitrary read/write. Therefore the conservative score remains borderline, while the paranoid score reaches Strong Important candidate due to memory lifetime corruption in a local user reachable DRM path. ## 5. One-sentence report phrase A local use-after-free in the drm xe dma-buf import path can leave an imported BO referencing a freed exporter reservation object, causing a kernel crash and requiring manual review for possible privilege escalation. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: explicit kernel UAF, local user reachable DRM path, asynchronous lifetime behavior, and plausible but unproven LPE potential. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/xe: Hold a dma-buf reference for imported BOs [ Upstream Commit: c22d65d62b3318e237c0e5b1177d90ab83d9fe06 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c22d65d62b3318e237c0e5b1177d90ab83d9fe06 Changed files: drivers/gpu/drm/xe/xe_bo.c drivers/gpu/drm/xe/xe_bo.h drivers/gpu/drm/xe/xe_bo_types.h drivers/gpu/drm/xe/xe_dma_buf.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=c22d65d62b3318e237c0e5b1177d90ab83d9fe06 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68266 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68266 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:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 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: 4 Paranoid ActionableScore: 7 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: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).