From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97521][LOW] gfs2: fix quota init duplicate scan [ Upstream Date: Thu, 24 Sep 2026 21:18:52 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97521 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: 7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 List-Id: CVE: CVE-2026-97521 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: gfs2: fix quota init duplicate scan [ Upstream Commit: 7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97521 Analysis date: Thu, 24 Sep 2026 21:18:52 -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-2026-97521 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97521 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-2026-97521 LOW https://www.kernelcve.org/list/?q=CVE-2026-97521 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:H/UI:N/S:U/C:N/I:N/A:L';CWE-667;*CWE-833;CWE-703;BEST CVSS score: '1.9';DESCR 'A locking context bug in GFS2 quota initialization can call lockref_get_not_dead while qd_lock and a quota hash bucket lock are held. On PREEMPT_RT the lockref operation may sleep, which can trigger a sleeping function called from invalid context warning and may disrupt quota initialization or GFS2 mount processing. For the CVSS the PR:H metric reflects that reliable triggering normally requires administrative control over a GFS2 filesystem, quota metadata, or its backing block device in order to introduce duplicate quota identifiers. The issue is not directly network reachable. Impact is limited to local denial of service or failed filesystem initialization. No memory corruption, information disclosure, integrity impact, or privilege escalation primitive is indicated by the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES DANGER DISK IMPROVEONLY SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=NONE RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 0 * Conservative score: 0 * Raw paranoid score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate**:: The patch establishes an invalid locking context on PREEMPT_RT, but not a memory-corruption, lifetime, authorization, information-disclosure, or integrity primitive. 2. Signal breakdown * +0 Invalid locking context: `lockref_get_not_dead()` may sleep while `qd_lock` and a quota hash bucket bitlock are held. The demonstrated symptom is a sleeping-in-atomic-context warning. * +0 Crash or strong DoS not established: the supplied evidence reports a syzbot warning, not a demonstrated kernel panic, filesystem shutdown, deadlock, or host-wide denial of service. * +0 No UAF: the no-reference lookup avoids taking a `lockref` while locks are held. It does not show an object freed while a stale user remains. * +0 No repeated release/refcount mutation: removal of `qd_put(old_qd)` follows removal of the corresponding reference acquisition. The old code obtained the reference with `lockref_get_not_dead()`, and the patch removes both operations from this path. This is balanced reference handling, not double put or post-free refcount mutation. * +0 Controlled reclaim, arbitrary write, structured stale-object leverage, information disclosure, integrity impact, privilege escalation, and authorization bypass are not demonstrated. * +0 Remote reachability is not established. * No negative privilege, niche-subsystem, or race penalties were applied because the supplied evidence does not positively establish those restrictions as part of the complete trigger chain. 3. Reachability analysis The affected path is `gfs2_quota_init()` while scanning quota-change records for duplicate quota identifiers during GFS2 initialization. The problematic condition requires GFS2 quota processing, PREEMPT_RT behavior, and duplicate identifiers in the `quota_change` metadata. The supplied patch does not establish whether an ordinary local user, a namespace-scoped administrator, or only a host administrator can create the required malformed or duplicate quota metadata and invoke the complete mount or initialization path. Therefore, `HostAdminRequired` and `NamespaceScopedPrivilege` are `UNKNOWN`. No network-triggerable path, special hardware dependency, or attacker-controlled lifetime transition is established. 4. Primitive and severity interpretation The exact defect is sleeping in an invalid atomic locking context. `gfs2_qd_search_bucket()` previously acquired a `lockref` reference while the caller held spin-style locks. On PREEMPT_RT, that reference operation may sleep, which is invalid under the held bucket lock. This is neither fixed stale storage nor an active structured-object UAF. There is no evidence that `qd` becomes freed while still being consumed. The patch replaces a reference-taking lookup with a no-reference lookup because the duplicate-detection caller only needs to inspect the existing quota object while holding the relevant locks. The demonstrated consequence is a kernel warning and possible failure or disruption of quota initialization. A stronger crash, filesystem corruption, privilege escalation, or confidentiality/integrity consequence is speculative and not supported by the patch. `PrimitiveClass=NONE`, `ImportantCandidate=NO`, and automatic downgrade is appropriate. 5. One-sentence report phrase A GFS2 quota initialization path can call a potentially sleeping lockref operation while holding spin-style locks on PREEMPT_RT, causing an invalid locking-context warning without a demonstrated memory-corruption or privilege-escalation primitive. 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch fixes a lock-context correctness issue with no established UAF, refcount corruption, authorization bypass, data corruption, or meaningful security primitive. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: gfs2: fix quota init duplicate scan [ Upstream Commit: 7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 Changed files: fs/gfs2/quota.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=7fdcf16e5e14e11028f5bcaa6d25075eb5e876a0 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97521 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97521 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:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS score: 1.9 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).