From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97483][LOW] usb: core: hcd: fix possible deadlock in rh control transfers [ Upstream Date: Thu, 24 Sep 2026 20:06:42 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97483 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: unknown X-AL-KERNEL-Commit: fff917c85d37a294397c5440a795591ca9d6b602 List-Id: CVE: CVE-2026-97483 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: usb: core: hcd: fix possible deadlock in rh control transfers [ Upstream Commit: fff917c85d37a294397c5440a795591ca9d6b602 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fff917c85d37a294397c5440a795591ca9d6b602 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97483 Analysis date: Thu, 24 Sep 2026 20:06:42 -0400 ActionableScore: 1 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-2026-97483 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97483 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-2026-97483 LOW https://www.kernelcve.org/list/?q=CVE-2026-97483 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-833;CWE-667;**CWE-400;BEST CVSS score: '4.2';DESCR 'A deadlock can occur during SCSI error recovery for a UAS USB storage device because root hub control transfer handling allocates memory with GFP_KERNEL even when the caller passes IO restricted allocation flags. A device reset may require resume and control transfers to the root hub. Memory reclaim from the SCSI error handler can then initiate IO and deadlock the recovery path. For the CVSS the PR:N because an attacker controlling a physically connected USB device does not need privileges on the target system. The attack vector is physical and requires a specific UAS error and reset sequence. Impact is denial of service through stalled storage recovery or blocked IO. No information disclosure integrity impact or privilege escalation primitive is indicated by the patch.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES DEADLOCK USB SIMPLEFIX HARDWARE LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. 2. Signal breakdown * +1 Reliable kernel availability impact. The patch establishes a possible deadlock in the SCSI error recovery path when root hub control transfer allocation uses GFP_KERNEL and may recursively trigger IO. A deadlock can stall recovery and block storage IO. * No UAF, stale reference, double release, refcount mutation, OOB access, invalid free, arbitrary write, or active-object lifetime violation is established. * No controlled reclaim, object replacement, attacker-controlled post-free data, callback influence, information disclosure, integrity impact, authorization bypass, or LPE primitive is demonstrated. * No remote reachability bonus. The affected path depends on a local USB UAS storage topology and SCSI error recovery, not network traffic. * No firmware-mediated attacker-control bonus. The supplied patch shows device error handling but does not establish that an attacker-controlled USB device can reliably induce the required error and reset sequence. * No hardware penalty. USB UAS storage is not inherently rare hardware, although physical device access and a specific recovery sequence are material practical prerequisites. * No hard-race penalty. The issue is an allocation-context deadlock, not a timing race. * No separate Availability point. The potential blocked IO and deadlock are the same consequence already counted by the strong DoS signal. 3. Reachability analysis The direct affected path is USB UAS storage error recovery. A reset of a UAS device can require resume operations and root hub control transfers. The root hub path previously allocated memory using GFP_KERNEL instead of preserving the caller allocation flags such as GFP_NOIO. The patch does not establish a complete attacker-controlled trigger chain. A malicious or malfunctioning physically connected USB UAS device may be relevant, but the supplied evidence does not prove that an attacker can reliably force the required SCSI error, reset, memory-reclaim condition, and deadlock without additional host configuration or workload conditions. Host-admin-equivalent privilege is not positively established as required, but below-host-admin attacker reachability is also not positively established for the complete trigger. Therefore HostAdminRequired is UNKNOWN. No namespace-scoped capability or namespace-local trigger is involved. NamespaceScopedPrivilege is UNKNOWN. 4. Primitive and severity interpretation The exact defect is an allocation-context violation. Root hub control transfers execute synchronously, but rh_call_control allocated a temporary descriptor buffer with GFP_KERNEL even when usb_hcd_submit_urb received restrictive allocation flags. During SCSI error handling, GFP_KERNEL allocation may enter reclaim and initiate IO, recursively interacting with the storage recovery path and causing deadlock. This is neither active structured-object corruption nor fixed stale storage. There is no UAF, refcount misuse, second release, cleanup-time stale dereference, memory overwrite, or semantic security-boundary bypass. The demonstrated consequence is a possible storage recovery deadlock and resulting denial of service. The primitive is classified as NONE because the patch establishes a deadlock condition but no meaningful corruption, lifetime, ownership, authorization, or disclosure primitive. ImportantCandidate is NO because no unresolved exploitation leverage beyond availability impact exists. AutoDowngradeAllowed is YES because the issue is a constrained DoS-only defect without a demonstrated kernel-corruption or security-boundary primitive. 5. One-sentence report phrase A root hub control transfer could allocate memory with GFP_KERNEL during UAS SCSI error recovery despite IO restricted caller flags, potentially causing recursive IO and a storage recovery deadlock. 6. Manual review recommendation NO MANUAL CHECK NEEDED The supplied patch supports a constrained deadlock and storage IO denial of service scenario only. No memory-corruption, privilege-escalation, confidentiality, integrity, or security-boundary primitive is established. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: usb: core: hcd: fix possible deadlock in rh control transfers [ Upstream Commit: fff917c85d37a294397c5440a795591ca9d6b602 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fff917c85d37a294397c5440a795591ca9d6b602 Changed files: drivers/usb/core/hcd.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=fff917c85d37a294397c5440a795591ca9d6b602 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97483 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97483 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: Not available The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.2 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: 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).