From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64486][LOW] ALSA: cmipci: check snd_ctl_new1() return value Date: Sat, 25 Jul 2026 15:37:12 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64486 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: b44888c33c4f11277d0e5e023338f2740232a4ed List-Id: CVE: CVE-2026-64486 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: YES Patch: ALSA: cmipci: check snd_ctl_new1() return value Commit: b44888c33c4f11277d0e5e023338f2740232a4ed Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b44888c33c4f11277d0e5e023338f2740232a4ed Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64486 Analysis date: Sat, 25 Jul 2026 15:37:12 -0400 ActionableScore: 1 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: ALSA cmipci may dereference a NULL mixer control pointer during driver initialization if `snd_ctl_new1()` fails under memory pressure, causing a local hardware-specific denial of service without evidence of privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64486 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64486 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-2026-64486 LOW CHECK WITH IMPACT FROM ORIG NN NONE 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-476;CWE-252;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'ALSA cmipci can dereference a NULL kctl pointer during mixer initialization if snd_ctl_new1() fails under memory pressure and the return value is not checked before using kctl id device. This is a local and hardware specific failure path in driver initialization rather than a packet or remote input path. For the CVSS the PR:L is used for the paranoid score because a local unprivileged process may be able to contribute to memory pressure while driver probing or reload is triggered by the system, but reliable triggering usually needs stronger local control. Impact is denial of service via kernel crash or failed device initialization. There is no supported UAF, OOB access, or write primitive in the provided code path, so confidentiality and integrity remain N.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES NULLPTR NOMEMCHK SIMPLEFIX HARDWARE LINUS KPANIC NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Triggered positive signals: * Reliable kernel crash / strong DoS: +1 A failed `snd_ctl_new1()` allocation can return NULL and the old code dereferenced `kctl->id.device`, causing a NULL pointer dereference. This is a crash or failed initialization path. Possible but weak signal: * Local unprivileged trigger: +0 conservative, +1 paranoid A local unprivileged user may be able to contribute to memory pressure, but reliable triggering also depends on driver probing or reload and specific hardware. This is too indirect for the conservative score. Negative signals: * Requires admin/root/CAP_* in typical deployments: -2 conservative Reliable triggering normally requires loading, probing, or reinitializing the ALSA PCI driver, which is usually administrator controlled. * Physical-only or rare hardware-only condition: -2 The affected path is specific to CMI PCI audio hardware and the SPDIF/AC3 control setup path. * Hard or unreliable triggering condition: -1 The NULL dereference requires allocation failure at a narrow driver initialization point. Not awarded: * No generic memory corruption bonus. This is a NULL pointer dereference, not UAF, OOB write, double free, type confusion, or arbitrary write. * No privilege escalation bonus. No reclaim, overwrite, callback control, refcount abuse, or object replacement is shown. * No confidentiality or integrity impact. The code path supports DoS only. ## 3. Reachability analysis The bug is reachable during ALSA cmipci mixer/control initialization when `cm->can_ac3_hw` is true and `snd_ctl_new1()` fails. In typical deployments, users do not directly control this path unless they can trigger driver load, device reprobe, module reload, or severe memory pressure at the right time. Namespaces and containers do not materially improve reachability unless the container or delegated service can control host device probing or module lifecycle. The path is not network reachable and is not a common default data-plane interface. ## 4. Severity interpretation This behaves like a Low-like or ordinary Moderate kernel DoS issue, not an Important-class vulnerability. The theoretical impact is a kernel NULL pointer dereference or device initialization failure under memory pressure. Realistic exploitation evidence for privilege escalation is absent. The patch is a straightforward error-handling fix that converts allocation failure into `-ENOMEM` instead of dereferencing NULL. ## 5. One-sentence report phrase ALSA cmipci may dereference a NULL mixer control pointer during driver initialization if `snd_ctl_new1()` fails under memory pressure, causing a local hardware-specific denial of service without evidence of privilege escalation. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: this is a hardware-specific allocation-failure NULL dereference in driver initialization, with no UAF, OOB write, stale callback, object replacement, info leak, or privilege escalation primitive shown. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ALSA: cmipci: check snd_ctl_new1() return value Commit: b44888c33c4f11277d0e5e023338f2740232a4ed Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b44888c33c4f11277d0e5e023338f2740232a4ed Commit description: snd_ctl_new1() can return NULL when memory allocation fails. snd_cmipci_spdif_controls() does not check the return value before dereferencing kctl->id.device, which can lead to a NULL pointer dereference. Add NULL checks after snd_ctl_new1() calls and return -ENOMEM if any fails. Assisted-by: Opencode:DeepSeek-V4-Flash Cc: stable@vger.kernel.org Fixes: f2f312a ("ALSA: cmipci: Fix kctl->id initialization") Signed-off-by: Zhao Dongdong Link: https://patch.msgid.link/tencent_964433DCD132125D5EDA79EE068A2D6EFA09@qq.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman Changed files: sound/pci/cmipci.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=b44888c33c4f11277d0e5e023338f2740232a4ed ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64486 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64486 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:N/I:N/A:H 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: 0 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: LOW KPANIC detected for this report: YES 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).