From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72100][LOW] dm-integrity: fix a bug if the bio is out of limits Date: Sun, 16 Aug 2026 08:55:59 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72100 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: f7989286175f32db8605e767a1a2efc62e894dc8 List-Id: CVE: CVE-2026-72100 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: dm-integrity: fix a bug if the bio is out of limits Commit: f7989286175f32db8605e767a1a2efc62e894dc8 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7989286175f32db8605e767a1a2efc62e894dc8 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72100 Analysis date: Sun, 16 Aug 2026 08:55:59 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: An out-of-limits bio in dm-integrity inline mode could return DM_MAPIO_KILL after a range was already locked, leaving the range locked and causing a local storage I/O deadlock. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72100 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72100 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-2026-72100 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-833;CWE-667;*CWE-772;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'dm-integrity inline mode can deadlock when an out of limits bio reaches dm_integrity_map_inline after the code has already locked the affected range. The error path returns DM_MAPIO_KILL without releasing that range lock, so later I/O touching the same protected range may block indefinitely and the mapped device can become unavailable. For the CVSS the PR:L is used in the paranoid score because a local user or process with access to a dm-integrity backed block device or delegated storage management path may be able to reach this mapper path, although reliable triggering may require a special block layout or admin controlled configuration. The issue is not network reachable and does not show a memory corruption primitive. Impact is denial of service only through a stuck I/O path or device level deadlock.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES DEADLOCK DISK SIMPLEFIX LEAK IMPROVEONLY LINUS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH YES NO 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 leave a dm-integrity range locked and cause later I/O to block indefinitely. * Availability impact realistic: +1. The affected mapped device or I/O path can become unavailable until recovery or reboot. * Important filesystem/storage path: +1. dm-integrity is a block/device-mapper storage integrity path. * Requires admin/root/CAP_* in typical deployments: -2. Creating and configuring dm-integrity mappings normally requires administrative storage privileges. * Hard or special triggering conditions: -1. The bio must be out of dm-integrity limits after the range has already been locked, which suggests a specific mapper/layout/error-path condition rather than a normal write. Paranoid adjustment: * Local unprivileged trigger: +1. If an unprivileged local process can issue I/O to an already configured dm-integrity backed block device and can reach the out-of-limits bio path through stacking or delegated storage access, it may trigger the deadlock without full storage admin rights. * Rare AND difficult-to-reach subsystem/configuration: -1. Inline dm-integrity mode and the out-of-limits condition are not broad default paths. No memory corruption signals apply. The patch shows a missed unlock/resource cleanup ordering bug, not UAF, double free, OOB write, type confusion, arbitrary write, or page-cache corruption. ## 3. Reachability analysis The bug is local and storage-path dependent. In typical deployments, configuring dm-integrity and producing invalid mapper geometry requires administrator-level control, so the conservative interpretation uses privileged reachability. A paranoid interpretation allows PR:L-like reachability if a local user or service can submit I/O to an already configured dm-integrity device and the device-mapper stack can generate an out-of-limits bio. Namespaces do not normally make this broadly reachable unless block-device or storage-management access is explicitly delegated. The path is not network reachable and is not default-enabled on ordinary systems. Call-site confidence: medium-high. The changed function and failing error path are visible, and the commit explicitly states that the range was already locked, but the full lock/unlock implementation is not included in the supplied diff. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like storage DoS issue. The realistic impact is a device-level or I/O-path deadlock. There is no supported privilege escalation path and no demonstrated confidentiality or integrity impact. The theoretical worst case remains availability-only because the patch moves validation before locking and does not repair a memory lifetime or overwrite primitive. ## 5. One-sentence report phrase An out-of-limits bio in dm-integrity inline mode could return DM_MAPIO_KILL after a range was already locked, leaving the range locked and causing a local storage I/O deadlock. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be handled as an auto-close or low-priority Moderate unless the affected product relies heavily on dm-integrity inline mode for critical storage. The issue is DoS-only, local, configuration-dependent, and has no concrete memory corruption or privilege-escalation primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: dm-integrity: fix a bug if the bio is out of limits Commit: f7989286175f32db8605e767a1a2efc62e894dc8 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f7989286175f32db8605e767a1a2efc62e894dc8 Commit description: If dm_integrity_check_limits fails, the code would exit with DM_MAPIO_KILL. However, the range would be already locked at this point, and it wouldn't be unlocked, resulting in a deadlock. Let's move the limit check up, so that when it exits, no resources are leaked. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-4.6 Fixes: fb09876 ("dm-integrity: introduce the Inline mode") Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/md/dm-integrity.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=f7989286175f32db8605e767a1a2efc62e894dc8 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72100 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72100 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: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).