From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98314][MODERATE REGULAR] ALSA: pcm: set timer->private_data before registering the PCM timer [ Upstream Date: Fri, 09 Oct 2026 13:37:35 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98314 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: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 27f167e117eca310661fbcbacb352ea08face067 List-Id: CVE: CVE-2026-98314 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: ALSA: pcm: set timer->private_data before registering the PCM timer [ Upstream Commit: 27f167e117eca310661fbcbacb352ea08face067 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=27f167e117eca310661fbcbacb352ea08face067 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98314 Analysis date: Fri, 09 Oct 2026 13:37:35 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98314 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98314 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-98314 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98314 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, 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:N/I:N/A:H';CWE-362;CWE-665;**CWE-476;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race in snd_pcm_timer_init() makes a new ALSA PCM timer visible in the global timer list before timer private_data is assigned. A concurrent local process can reach the timer through /proc/asound/timers or the ALSA timer interface and invoke c_resolution(), start(), or stop(), which dereference the still NULL private_data pointer. The demonstrated primitive is a NULL pointer dereference rather than a UAF or controlled memory corruption. Impact is a kernel Oops and local denial of service, with a possible full kernel crash when panic_on_oops is enabled. For the CVSS the PR:L reflects that a local user or process is required to access the exposed ALSA or procfs interface. AC:H reflects the need to hit the brief race window while a PCM timer is being registered. The issue is not network reachable. There is no supported path to confidentiality impact, integrity impact, or privilege escalation from the analyzed code.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE DANGER INIT TIMER HARDWARE LINUS SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Local unprivileged trigger. A local reader can reach the callbacks through `/proc/asound/timers`. ALSA timer interfaces provide another local path, although their device permissions may vary. * +1 Reliable kernel fault or DoS. Dereferencing the NULL `timer->private_data` causes a kernel Oops and can cause a host crash when fatal Oops handling is enabled. * -1 Hard timing requirement. The reader must enter the callback during the explicitly described brief interval between timer registration and `private_data` initialization. * No UAF signal. The object has not been freed, released, or reused. * No OOB-write signal. The NEW52 B5-R profile does not apply because there is no heap OOB write, retry-accumulated offset, corrupted descriptor, or later consumption of OOB-corrupted state. * No strong or weak corruption bonus. The established operation is a NULL dereference with no controlled target, payload, reclaim, or write. * No extra Availability point. The Oops or panic is the same consequence already counted as kernel DoS. * No Confidentiality or Integrity points. No disclosure, unauthorized modification, or privilege-escalation primitive is established. * No remote-reachability point. The exposed paths are local. * No broad-subsystem point. ALSA is common, but reaching this short initialization window is not shown to be routine enough for a separate exposure bonus. 3. Reachability analysis A local process can repeatedly read `/proc/asound/timers`, causing `c_resolution()` to run when timers are enumerated. A process with access to the ALSA timer device can also reach the `start()` and `stop()` callbacks. The procfs path establishes below-host-admin callback reachability, so host-admin-equivalent privilege is not required. The attacker does not appear to control timer publication directly. Exploitation depends on an independent PCM timer registration occurring concurrently, such as during sound-device initialization or another PCM setup event. This makes the race narrow and reduces reliability. No network namespace or namespace-scoped capability participates in the trigger. No special or rare hardware requirement is established beyond the presence of a usable ALSA PCM device. There is no network-triggerable path. 4. Primitive and severity interpretation The exact primitive is publication of a partially initialized `struct snd_timer`, followed by a concurrent callback that reads a NULL `private_data` pointer and dereferences it as a `struct snd_pcm_substream`. This is an active object initialization race, but not a lifetime violation. The timer remains allocated and registered. There is no stale post-lifetime reference, first release, second release, refcount mutation, controlled reclaim, or replacement object. The appropriate classification is CLASS_C because the demonstrated behavior is an invalid NULL dereference and availability failure without an independently useful corruption primitive. The practical consequence is a kernel Oops and potentially a full panic under fatal Oops policy. Privilege escalation, information disclosure, and controlled kernel-state modification are unsupported. ImportantCandidate is NO because there is no Class A or Class B primitive and no unresolved exploitation mechanism beyond the crash. AutoDowngradeAllowed is YES because the issue is a constrained race-driven NULL dereference with no UAF, OOB write, ownership violation, authorization bypass, or useful post-crash primitive. 5. One-sentence report phrase A local process can race ALSA PCM timer registration through procfs or the ALSA timer interface and invoke a callback before private_data is initialized, causing a NULL pointer dereference and kernel denial of service. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm the actual permissions of `/proc/asound/timers`, the available mechanisms for inducing PCM timer registration, and whether the evaluated kernel treats the resulting Oops as fatal. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ALSA: pcm: set timer->private_data before registering the PCM timer [ Upstream Commit: 27f167e117eca310661fbcbacb352ea08face067 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=27f167e117eca310661fbcbacb352ea08face067 Changed files: sound/core/pcm_timer.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=27f167e117eca310661fbcbacb352ea08face067 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98314 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98314 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: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: unknown Paranoid ActionableScore: 1 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).