From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99219][LOW] ftrace: Initialize modname and offset in print_rec() Date: Mon, 02 Nov 2026 22:18:00 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99219 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: 1 X-AL-KERNEL-Commit: 753d5cba113a52cb155428f4ea93a4b0148c4bf1 List-Id: CVE: CVE-2026-99219 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ftrace: Initialize modname and offset in print_rec() Commit: 753d5cba113a52cb155428f4ea93a4b0148c4bf1 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=753d5cba113a52cb155428f4ea93a4b0148c4bf1 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99219 Analysis date: Mon, 02 Nov 2026 22:18:00 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A timed tracefs read can pass an uninitialized module-name pointer to `seq_printf()`, causing a kernel Oops and possibly an unconfirmed limited disclosure. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99219 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99219 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-2026-99219 LOW https://www.kernelcve.org/list/?q=CVE-2026-99219 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H';CWE-824;*CWE-457;CWE-362;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'An uninitialized pointer dereference in ftrace print_rec occurs when kallsyms_lookup fails during module loading or unloading and leaves modname and offset unchanged. A concurrent read of available_filter_functions can pass a garbage modname value through the pointer check and seq_printf can treat it as a string pointer, causing a kernel Oops and potentially a system panic. If the garbage pointer references mapped memory, limited kernel data disclosure through the tracefs output is plausible but not demonstrated or controllable. For the CVSS the PR:L value reflects a local process that can read the relevant tracefs file. AC:H reflects the required timing with module loading or unloading. The issue is not directly network reachable and no write primitive or supported privilege escalation path is present. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 5.3 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to LOW because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS unavailable and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE TRACE LEAK LINUS V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES RequiresHostUID0=NO AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1. * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 2. * Paranoid score: 2; no floor or cap applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Reliable kernel crash/strong DoS: failed `kallsyms_lookup()` leaves `modname` uninitialized; a garbage non-NULL pointer reaches `seq_printf()` and the supplied trace confirms an Oops. * +1 Local unprivileged trigger: supplied evidence grounds reading `available_filter_functions` from a local low-privilege process. * -1 Hard timing requirement: lookup failure requires the read to coincide with module loading or unloading, which the reader is not shown to control. * Paranoid +1 Confidentiality plausible: if the garbage pointer happens to reference mapped memory, `%s` may return bytes through the seq-file read rather than faulting. This is a concrete output path, but no successful disclosure or pointer control is demonstrated. * No UAF, OOB write, shared-backing write, authorization bypass, controlled target, or privilege-escalation primitive is shown. * No extra availability point is awarded for the same Oops. NEW52 B5-R and NEW53 B3-PENDING do not apply. 3. Reachability analysis A below-host-admin local reader can exercise the vulnerable tracefs read, so host UID 0 is not required for that operation. However, successful triggering depends on a concurrent module lifecycle event; the attacker is not shown able to initiate it. Namespace capability scope is not established. No remote path, special hardware, or attacker-controlled retry sequence exists. 4. Primitive and severity reading The primitive is an uninitialized stack pointer consumed as a string pointer. It is neither active structured-state corruption nor a lifetime violation. The demonstrated result is an invalid dereference and kernel Oops, hence CLASS_C. Limited disclosure is technically possible through `seq_printf()` but remains unconfirmed and uncontrollable. There is no Important-preserving corrupt or trust-boundary chain, so automatic Moderate downgrade remains permissible. 5. One-sentence report phrase A timed tracefs read can pass an uninitialized module-name pointer to `seq_printf()`, causing a kernel Oops and possibly an unconfirmed limited disclosure. 6. Manual review advice MANUAL CHECK RECOMMENDED Confirm tracefs permissions, panic-on-oops policy, and whether any successful mapped-pointer disclosure is reproducible. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ftrace: Initialize modname and offset in print_rec() Commit: 753d5cba113a52cb155428f4ea93a4b0148c4bf1 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=753d5cba113a52cb155428f4ea93a4b0148c4bf1 Commit description: print_rec() leaves 'modname' and 'offset' uninitialized and kallsyms_lookup() only sets them on success. When the lookup fails like when a module is being loaded or unloaded, 'modname' holds a garbage value, passes the 'if (modname)' check, and is dereferenced by seq_printf(). Oops: general protection fault RIP: 0010:string+0x48/0xe0 Call Trace: vsnprintf+0x1f5/0x650 seq_printf+0x8e/0xb0 print_rec+0x6c/0xc0 t_show+0x4c/0x440 seq_read_iter+0x119/0x480 This can be triggered by reading available_filter_functions while a module is being loaded or unloaded. Initialize both variables so a failed lookup skips the module name. Cc: stable@vger.kernel.org Fixes: b39181f ("ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function") Link: https://patch.msgid.link/20261016230403.4916-1-aarnahmd@amazon.com Tested-by: Gavin Inglis Signed-off-by: Aaron Ahmed Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman Changed files: kernel/trace/ftrace.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=753d5cba113a52cb155428f4ea93a4b0148c4bf1 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99219 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99219 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:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H The Best / paranoid CVSS score: 5.3 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: 1 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).