From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53118][MODERATE REGULAR] vdpa: use generic driver_override infrastructure [ Upstream Date: Wed, 24 Jun 2026 14:09:46 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53118 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: 4 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: 654ef9c33e138ede6734ac286282df9faf83cd11 List-Id: CVE: CVE-2026-53118 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: vdpa: use generic driver_override infrastructure [ Upstream Commit: 654ef9c33e138ede6734ac286282df9faf83cd11 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=654ef9c33e138ede6734ac286282df9faf83cd11 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53118 Analysis date: Wed, 24 Jun 2026 14:09:46 -0400 ActionableScore: 4 ActionableScore lower bound: 1 Actionable bucket: Borderline manual review / not auto-close solely by CVSS Manual review required: YES Summary: A local race in vDPA `driver_override` handling can let `vdpa_dev_match()` read a freed override string during driver attach, causing a UAF-triggered kernel crash, with practical exploitation usually requiring privileged or delegated device-management access. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53118 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53118 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-53118 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'A race in the vDPA bus driver_override handling can lead to a use after free because vdpa_dev_match reads the override pointer during __driver_attach while the device lock is not held. A concurrent sysfs update can replace or free the same driver_override string, so strcmp can read freed memory during driver matching and crash the kernel. For the CVSS the PR:L paranoid case represents environments where a reduced capability root, container root, or service account can modify vDPA sysfs binding controls or trigger driver reprobe without full host administration. The issue is local and not network reachable. Impact is at least denial of service, with limited confidentiality or integrity impact kept only for the paranoid score because the primitive is a UAF read during matching rather than an obvious arbitrary write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review / not auto-close solely by CVSS (with actual score 3) YES LOCK UAF HARDWARE LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 4 * Final recommended bucket: **Borderline manual review / not auto-close solely by CVSS**:: ## 2. Signal breakdown Conservative signals: * Memory corruption, weak primitive: +1 The patch explicitly describes a UAF, but the visible primitive is a stale string pointer read by `strcmp()` during driver matching. * Real lifetime corruption: +1 `driver_override` can be freed or replaced while `vdpa_dev_match()` reads it without the device lock. * Reliable kernel crash / strong DoS: +1 A freed pointer dereference in `strcmp()` can plausibly crash the kernel. * Hard or unreliable race / special timing required: -1 Triggering requires concurrent driver attach/probe and sysfs override modification. * Requires admin/root/device-management privilege in typical deployments: -2 Writing `driver_override` and triggering driver binding paths is normally restricted to root or privileged device-management tooling. * Privileged kernel/device-management lifetime path: +1 The bug is in driver-core style binding logic for vDPA devices, a trusted kernel device-management path. Paranoid additional interpretation: * Local low-privilege trigger: +1 In environments where vDPA device sysfs controls are delegated to container root, reduced-capability root, or a service account, the practical privilege level can be closer to PR:L than PR:H. * No Weak LPE concern awarded The patch does not show attacker-controlled reclaim, stale object replacement, writable UAF access, callback dispatch, type confusion, or refcount takeover. * No C/I impact awarded for the conservative score The concrete primitive is a race UAF read in string comparison. Confidentiality or integrity impact is not demonstrated. ## 3. Reachability analysis The issue is local and not network reachable. A realistic trigger needs access to vDPA device binding or `driver_override` sysfs controls plus a concurrent driver attach path. In normal host deployments this is root or administrative device-management access, so the conservative interpretation applies a strong privilege penalty. In delegated virtualization or container-management environments, a reduced-privilege service or container root may be allowed to manipulate device binding controls, making the paranoid PR:L interpretation reasonable. The affected subsystem is not a broad default attack surface for ordinary users. It is relevant mostly on systems using vDPA or virtualization-related device management. ## 4. Severity interpretation This behaves more like a borderline manual-review Moderate than an Important-class vulnerability. The bug is a real UAF race, which prevents automatic dismissal, but the demonstrated primitive is a stale pointer read during driver matching rather than a controlled write, object replacement, callback hijack, or clear LPE primitive. Realistic impact is kernel crash or warning-driven DoS. A stronger exploitation path would require additional evidence of controllable reclaim or meaningful object reuse. ## 5. One-sentence report phrase A local race in vDPA `driver_override` handling can let `vdpa_dev_match()` read a freed override string during driver attach, causing a UAF-triggered kernel crash, with practical exploitation usually requiring privileged or delegated device-management access. ## 6. Manual review recommendation MANUAL CHECK REQUIRED The patch explicitly fixes a UAF in a kernel driver-binding path. Even though the visible primitive is weak and typical triggering is privileged, UAF lifetime bugs should not be auto-closed without confirming whether delegated sysfs access, container device management, or attacker-influenced object reuse exists in the target environment. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: vdpa: use generic driver_override infrastructure [ Upstream Commit: 654ef9c33e138ede6734ac286282df9faf83cd11 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=654ef9c33e138ede6734ac286282df9faf83cd11 Changed files: drivers/vdpa/vdpa.c include/linux/vdpa.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=654ef9c33e138ede6734ac286282df9faf83cd11 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53118 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53118 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:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.8 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: 4 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).