From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97617][MODERATE REGULAR] ring-buffer: Check resize_disabled before publishing the new subbuf order Date: Fri, 25 Sep 2026 12:26:45 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97617 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: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: f2099644e1b2a2c0805c5240d63ab0522d9d0174 List-Id: CVE: CVE-2026-97617 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: ring-buffer: Check resize_disabled before publishing the new subbuf order Commit: f2099644e1b2a2c0805c5240d63ab0522d9d0174 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f2099644e1b2a2c0805c5240d63ab0522d9d0174 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97617 Analysis date: Fri, 25 Sep 2026 12:26:45 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97617 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97617 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-2026-97617 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97617 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H';CWE-362;CWE-125;*CWE-200;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '6.3';DESCR 'A race exists between ring_buffer_subbuf_order_set and the lockless mmap path. The order setter can publish a new subbuf_order before discovering that resizing is disabled and returning EBUSY. A concurrent __rb_map_vma operation can read the temporary order, calculate a larger mapping, and insert pages beyond the intended sub-buffer boundary into the user VMA. This provides a plausible out-of-bounds mapping and information disclosure primitive, while a malformed mapping may also cause a fault or availability impact. For the CVSS the PR:L value is used for the paranoid score because tracefs access can be delegated to a restricted service account, container root, or another user with limited tracing permissions. AC:H applies because successful triggering requires winning a race between mmap and the failing order change. The issue is locally triggered and is not network reachable. Impact is at least unintended page exposure and in the worst defensible case may include substantial confidentiality and availability impact. No writable mapping or concrete arbitrary write primitive is established, so integrity impact remains I:N.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) SKIP CVE-2026-97617 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE READ TRACE SIMPLEFIX HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 3 * Conservative score: 3 * Raw paranoid score: 4 * Paranoid score: 4 * No floor or cap was applied. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Conservative signals: * +1 Weak or indirect corruption candidate. The race creates inconsistent sub-buffer geometry and causes pages beyond the intended sub-buffer boundary to be inserted into a userspace VMA. * +1 Active-state synchronization bypass. An existing user mapping sets resize_disabled, but the vulnerable path publishes the replacement order before checking that guard. The fix restores the check before publication. * +1 Confidentiality plausible. The extra pages are mapped into a user-visible VMA, providing a concrete disclosure path rather than merely an internal kernel OOB read. Paranoid-only signal: * +1 Reliable kernel fault or strong DoS concern. The inconsistent order can make the mmap path walk or insert pages beyond the intended sub-buffer geometry. A host fault is technically defensible, although the commit does not document an observed panic. Not awarded: * No UAF or post-lifetime stale-object use is established. * No controlled reclaim, arbitrary write, writable unintended mapping, or attacker-directed target is demonstrated. * No integrity point was awarded because the evidence establishes page insertion into a VMA but not unauthorized modification through that mapping. * No remote-reachability point was awarded. * No local-unprivileged point was awarded because access to both mmap and sub-buffer order control below host-admin privilege is not established. * No race penalty was applied. The input does not establish that repeated attempts are impractical or that the timing window is one-shot. * No extra Availability point was awarded for the same possible fault. * No repeated release or refcount operation exists. The repeated-release signal and UAF floors do not apply. * The memory-layout invariant was not scored separately because it is the same underlying fact as the inconsistent out-of-range mapping. 3. Reachability analysis The complete trigger requires one path to attempt changing subbuf_order while another performs mmap against an already mapped CPU whose resize_disabled counter is set. The attacker therefore needs access to both the ring-buffer mapping interface and the order-changing control path, or cooperation with another actor performing the resize. The supplied evidence does not prove whether those operations require host-admin-equivalent tracing privileges or are available to a delegated tracing user. Therefore HostAdminRequired is UNKNOWN rather than YES or NO. No evidence establishes that the complete operation is governed by attacker-obtainable user-namespace or tracing-namespace privileges, so NamespaceScopedPrivilege is also UNKNOWN. The issue is local and not directly network-triggerable. No special hardware is required. A configured trace ring buffer and permission to access its mmap and resize interfaces are prerequisites. Although triggering requires a race, the evidence does not show that the race is intrinsically narrow or non-repeatable. 4. Primitive and severity interpretation The exact primitive is a transient mismatch between published sub-buffer order and the actual non-resized buffer layout. The lockless mmap path consumes the transient order and inserts pages beyond the intended sub-buffer boundary into a user VMA. This is an active mapping and synchronization violation, not a UAF, double release, or controlled overwrite. Its strongest patch-supported non-crash consequence is unintended user-visible page exposure. The extent and sensitivity of those pages are unresolved. A kernel fault is a defensible paranoid consequence, but it is not explicitly demonstrated. PrimitiveClass is CLASS_B because the patch establishes an independently useful out-of-range mapping and possible disclosure primitive, but not a strong controlled corruption primitive. ImportantCandidate is NO because substantial kernel disclosure, arbitrary access, integrity modification, LPE, and security-boundary bypass are not established. AutoDowngradeAllowed is YES because the unresolved behavior remains limited to constrained unintended mapping and possible DoS, without Class A leverage. Manual review is still recommended to determine exactly which pages become visible and whether the VMA is strictly read-only. 5. One-sentence report phrase A race between sub-buffer order publication and the lockless ring-buffer mmap path can map pages beyond the intended sub-buffer boundary into userspace, creating a local information-disclosure risk and a possible kernel fault. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Verify the maximum mapping overrun, the ownership and contents of the extra pages, VMA write permissions, and the actual privilege checks for mmap and sub-buffer resizing. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ring-buffer: Check resize_disabled before publishing the new subbuf order Commit: f2099644e1b2a2c0805c5240d63ab0522d9d0174 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f2099644e1b2a2c0805c5240d63ab0522d9d0174 Commit description: ring_buffer_subbuf_order_set() stores the new order and only then walks the CPUs, returning -EBUSY if any of them has resizing disabled. A user mapped buffer has resizing disabled, and __rb_map_vma() reads buffer->subbuf_order without buffer->mutex, so an mmap of an already mapped CPU racing the failing order change sizes the mapping with the new order and inserts pages past the sub-buffer into the VMA. Check the CPUs before storing the new order. Cc: stable@vger.kernel.org Fixes: 117c392 ("ring-buffer: Introducing ring-buffer mapping functions") Link: https://patch.msgid.link/20260912103938.1127021-1-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman Changed files: kernel/trace/ring_buffer.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=f2099644e1b2a2c0805c5240d63ab0522d9d0174 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97617 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97617 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:L/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H The Best / paranoid CVSS score: 6.3 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: 3 Paranoid ActionableScore: 4 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).