From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46184][LOW] sound: ua101: fix division by zero at probe Date: Thu, 28 May 2026 10:28:43 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46184 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: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 6162e8212e88c39492d981b248b5e37002486c66 List-Id: CVE: CVE-2026-46184 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: sound: ua101: fix division by zero at probe Commit: 6162e8212e88c39492d981b248b5e37002486c66 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6162e8212e88c39492d981b248b5e37002486c66 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46184 Analysis date: Thu, 28 May 2026 10:28:43 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A malformed UA-101 USB audio device can report zero channels, causing `frame_bytes` to become zero and later triggering a division-by-zero kernel crash in URB completion handlers. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46184 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46184 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-2026-46184 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-369;*CWE-20;CWE-754;BEST CVSS score: '4.6';DESCR 'The ua101 USB audio driver trusted bNrChannels from a class specific USB descriptor and could calculate frame_bytes as zero when a malformed device reported zero channels. Later URB completion handlers use frame_bytes as a divisor, which can trigger a division by zero and crash the kernel. For the CVSS the PR:N is used because the attacker only needs to present a malformed USB device, but the attack vector is physical device attachment rather than a network path. Impact is availability only. There is no supported memory corruption, information disclosure, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) MAYBE DANGER USB SIMPLEFIX ERRORPATH HARDWARE LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 0 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Positive signals: * Reliable kernel crash / strong DoS: +1. A malformed UA-101 USB audio device with `bNrChannels = 0` can make `frame_bytes` zero and later trigger division by zero in URB completion. * Availability impact realistic: +1. Kernel crash is the supported impact. Negative / limiting signals: * Physical-only condition: -2. The attacker must present a malformed physical USB device or equivalent USB passthrough device. * Rare device-specific driver path: -1. The issue affects the Edirol UA-101 USB audio driver, not a broad USB audio core path. * No memory corruption, information disclosure, integrity impact, or privilege escalation. Effective triage score is floored at 0. ## 3. Reachability analysis The practical trigger is attaching or passing through a malformed USB device that reports zero channels in class-specific descriptors. A local user normally needs physical access or control over USB passthrough. The issue is not remotely network reachable. Containers and VMs matter only if untrusted USB passthrough is allowed. In that case, the guest kernel may be crashed by the malformed device, but the primitive remains availability-only. ## 4. Severity interpretation This behaves like Low / ordinary Moderate. It is a device-specific physical DoS caused by missing descriptor validation. There is no evidence of memory corruption, information disclosure, or privilege escalation. The theoretical impact does not extend beyond kernel crash based on the patch. ## 5. One-sentence report phrase A malformed UA-101 USB audio device can report zero channels, causing `frame_bytes` to become zero and later triggering a division-by-zero kernel crash in URB completion handlers. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This is physical-device availability-only DoS in a specific USB audio driver, with no memory corruption or LPE evidence. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: sound: ua101: fix division by zero at probe Commit: 6162e8212e88c39492d981b248b5e37002486c66 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6162e8212e88c39492d981b248b5e37002486c66 Commit description: Add a missing sanity check for bNrChannels in detect_usb_format() to prevent a division by zero in playback_urb_complete() and capture_urb_complete(). USB core does not validate class-specific descriptor fields such as bNrChannels, so drivers must verify them before use. If a device provides bNrChannels = 0, frame_bytes becomes zero and is later used as a divisor in the URB completion handlers, leading to a kernel crash. Fixes: 63978ab ("sound: add Edirol UA-101 support") Cc: stable@vger.kernel.org Signed-off-by: SeungJu Cheon Link: https://patch.msgid.link/20260426111239.103296-1-suunj1331@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman Changed files: sound/usb/misc/ua101.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=6162e8212e88c39492d981b248b5e37002486c66 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46184 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46184 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: Not available The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.6 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: unknown Paranoid ActionableScore: 0 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).