From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80535][LOW] xfs: don't double-lock when deleting a self-referential directory Date: Wed, 26 Aug 2026 13:53:58 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80535 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: 2 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: 17bc347cbdfb125eddac0a815b1f6c1f6eb56676 List-Id: CVE: CVE-2026-80535 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: xfs: don't double-lock when deleting a self-referential directory Commit: 17bc347cbdfb125eddac0a815b1f6c1f6eb56676 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=17bc347cbdfb125eddac0a815b1f6c1f6eb56676 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80535 Analysis date: Wed, 26 Aug 2026 13:53:58 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A self-referential XFS directory can cause the online directory tree repair path to lock the same inode twice, leading to a local repair-path hang or DoS, typically requiring administrator-level filesystem repair access. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80535 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80535 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-2026-80535 LOW 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-667;*CWE-833;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A self-referential XFS directory can make the directory tree repair path treat the same inode as both the scrub target and the parent directory. The old logic could try to lock the same inode twice during unlink repair, which can lead to a deadlock or hang in the repair path. For the CVSS the PR:L paranoid interpretation applies only if an untrusted local actor can reach the repair path through delegated filesystem administration or a privileged repair service that processes attacker controlled XFS metadata. In normal deployments PR:H is more realistic because XFS online repair and mounting attacker controlled filesystems require administrative privileges. The issue is not network reachable. Impact is denial of service only via repair hang or filesystem operation stall. For the paranoid score, this uses the highest still defensible DoS interpretation and does not change the bug class.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) MAYBE DANGER DISK LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Conservative signals: * Reliable kernel crash / strong DoS: +1. The bug can deadlock or hang the XFS directory tree repair path by trying to lock the same inode twice. * Important filesystem/storage path: +1. The affected code is XFS online scrub repair for directory metadata. * Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Running XFS online repair and handling corrupted filesystem metadata normally requires administrator-level filesystem management. * Rare AND difficult-to-reach subsystem/configuration: -1. Triggering requires a self-referential corrupted directory and execution of the specific dirtree repair path. Conservative total is clamped to 0. Paranoid signals: * Local unprivileged trigger: +1. Only under a delegated or service-mediated model where an untrusted local actor can provide attacker-controlled XFS metadata to a privileged repair workflow. * Reliable kernel crash / strong DoS: +1. A repair-path hang or deadlock is plausible. * Important filesystem/storage path: +1. XFS metadata repair is security-relevant storage code. * Hard or special condition required: -1. The condition requires unusual filesystem corruption and a repair invocation. Paranoid total: 2. No memory corruption signal is awarded. The patch shows a double-locking logic bug, not UAF, OOB write, double free, stale pointer reuse, refcount misuse, page-cache corruption, or object confusion. ## 3. Reachability analysis Typical reachability is local and privileged. The affected path is XFS online scrub repair, not normal file I/O and not network reachable. A normal unprivileged user generally cannot invoke this repair path against arbitrary corrupted metadata. Namespaces and containers do not materially lower the conservative privilege requirement unless a container or service is explicitly delegated filesystem repair capabilities over attacker-controlled images or mounts. In such a special deployment, the paranoid PR:L-style interpretation is possible, but it is not the common case. Call-site confidence: high. The patch directly shows the affected lock and unlock paths in `xrep_dirtree_unlink()` and `xrep_dirtree_unlink_iolock()`. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like availability issue, not an Important-class vulnerability. The realistic impact is a repair-path deadlock or filesystem operation stall. There is no supported privilege escalation primitive and no confidentiality or integrity impact beyond the already corrupted filesystem metadata context. The theoretical risk remains DoS-only. The patch does not support upgrading this to memory corruption or LPE. ## 5. One-sentence report phrase A self-referential XFS directory can cause the online directory tree repair path to lock the same inode twice, leading to a local repair-path hang or DoS, typically requiring administrator-level filesystem repair access. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED. Reason: no memory corruption, no remote reachability, no privilege escalation path, and no practical unprivileged trigger in normal deployments. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: xfs: don't double-lock when deleting a self-referential directory Commit: 17bc347cbdfb125eddac0a815b1f6c1f6eb56676 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=17bc347cbdfb125eddac0a815b1f6c1f6eb56676 Commit description: LOLLM notices that the dirtree scrubber can detect a directory that refers to itself. In this case, it's not correct for the directory tree repair code to try to iolock/ilock both sc->ip and dp, because they're the same inode. Fix this by detecting that corner case and handling it appropriately. Cc: stable@vger.kernel.org # v6.10 Fixes: 3f31406 ("xfs: fix corruptions in the directory tree") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino Signed-off-by: Greg Kroah-Hartman Changed files: fs/xfs/scrub/dirtree_repair.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=17bc347cbdfb125eddac0a815b1f6c1f6eb56676 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80535 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80535 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: 0 Paranoid ActionableScore: 2 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).