From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64052][MODERATE REGULAR] block: bio-integrity: Fix null-ptr-deref in bio_integrity_map_user() [ Upstream Date: Sun, 19 Jul 2026 21:36:35 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64052 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: 3 X-AL-KERNEL-ActionableScore-Lower: 2 X-AL-KERNEL-Commit: 77c059f41e9395793917d067476f549a911d77d3 List-Id: CVE: CVE-2026-64052 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: block: bio-integrity: Fix null-ptr-deref in bio_integrity_map_user() [ Upstream Commit: 77c059f41e9395793917d067476f549a911d77d3 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77c059f41e9395793917d067476f549a911d77d3 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64052 Analysis date: Sun, 19 Jul 2026 21:36:35 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Borderline Moderate, manual review recommended Manual review required: YES Summary: `bio_integrity_map_user() can continue after partial user page pinning and pass missing page entries to bvec_from_pages(), allowing a local actor with access to the affected block or NVMe passthrough path to crash the kernel.` ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64052 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64052 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-2026-64052 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-754;CWE-252;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'bio_integrity_map_user() can continue after only part of the requested user memory was pinned. The later bvec_from_pages() call assumes that all page pointers are valid and can dereference a missing or NULL page entry, causing a kernel Oops or panic. For the CVSS the PR:L is used because reliable triggering requires local execution with access to the affected block or NVMe passthrough path, but this access may be delegated to a storage service, device group, or restricted container rather than full administrator rights. The issue is not network reachable by itself and requires a local block device interface with integrity metadata handling. Impact is denial of service via kernel crash. No concrete UAF, OOB write, arbitrary write, or information leak primitive is visible from the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate, manual review recommended (with actual score 3) YES KASAN OOB NULLPTR HARDWARE MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 ## 1. ActionableScore * Conservative score: 2 * Paranoid score: 3 * Final recommended bucket: **Borderline Moderate, manual review recommended**:: ## 2. Signal breakdown * Reliable kernel crash / strong DoS: +1 The commit includes a concrete KASAN null-ptr-deref and general protection fault in `bio_integrity_map_user()` after partial user-page pinning. * Important filesystem/storage path: +1 The bug is in the block layer bio-integrity path and is shown through an NVMe passthrough workload. * Local reduced-privilege trigger, paranoid only: +1 Reliable triggering requires local access to the affected block or NVMe passthrough path. This is often privileged, but in some deployments device access can be delegated to a storage service, device group, or containerized storage-management process. * Requires special storage/device access: -1 conservative only This is not a generic syscall reachable by any local user. It requires the bio-integrity path plus suitable block/NVMe interface access. * Generic memory corruption: +0 The demonstrated primitive is a NULL pointer dereference through an unpinned page slot. The patch does not show UAF, OOB write, arbitrary write, refcount takeover, or object replacement. * Privilege escalation plausible: +0 No concrete LPE primitive is visible. This behaves like a crash-only bug based on the patch and commit message. * Confidentiality / Integrity: +0 / +0 No information disclosure or data modification primitive is shown. ## 3. Reachability analysis A local process can trigger the issue only if it can reach the relevant block integrity mapping path, such as through NVMe passthrough or similar storage interfaces. In typical deployments this may require root or administrative device permissions, but some systems delegate storage access to services, groups, containers, or reduced-capability management processes. The path is not network reachable by itself. Exploitation conditions are realistic for a local actor with appropriate device access, but not for an arbitrary unprivileged user on a default locked-down system. Call-site confidence: medium-high. The immediate crashing call path to `bvec_from_pages()` is shown, and the commit identifies `nvme-passthroug`, but the full userspace permission model depends on deployment. ## 4. Severity interpretation This is best treated as a Moderate issue with manual review recommended. It has a concrete local kernel crash path in an important storage subsystem, but the evidence supports NULL dereference DoS rather than memory corruption or privilege escalation. The paranoid score keeps it above ordinary low-priority cleanup because storage device access may be delegated in real environments. ## 5. One-sentence report phrase `bio_integrity_map_user() can continue after partial user page pinning and pass missing page entries to bvec_from_pages(), allowing a local actor with access to the affected block or NVMe passthrough path to crash the kernel.` ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: the bug is crash-only based on current evidence, but it is in a storage/block integrity path where real exposure depends heavily on local device permissions, NVMe passthrough policy, and delegated storage-management access. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: block: bio-integrity: Fix null-ptr-deref in bio_integrity_map_user() [ Upstream Commit: 77c059f41e9395793917d067476f549a911d77d3 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77c059f41e9395793917d067476f549a911d77d3 Changed files: block/bio-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=77c059f41e9395793917d067476f549a911d77d3 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64052 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64052 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:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.5 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: 2 Paranoid ActionableScore: 3 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).