CVE-2021-47037 is a vulnerability identified in the Linux kernel specifically affecting the q6afe-clocks driver, which is part of the ALSA System on Chip (ASoC) subsystem. The issue arises during the reprobe process of the q6afe-clocks driver, which can occur, for example, when APR (Asynchronous Packet Router) services are restarted following a firmware crash. The vulnerability is due to improper handling of the driver's hardware initialization state. During the first probe call, the hardware initialization data (hw.init) is cleared, but the driver relies on a large static array of clock data that does not get properly reinitialized at runtime. This leads to a kernel oops (a type of kernel panic or crash) when the driver is reprobed because it attempts to access uninitialized or cleared hardware data structures. The root cause is that the driver’s clock data is statically defined rather than dynamically populated at runtime, which is problematic when the driver is reprobed multiple times. The fix involves rewriting the driver to fill the clock data dynamically during runtime instead of relying on static arrays, ensuring that the driver can safely handle reprobes without causing kernel crashes. This vulnerability does not have any known exploits in the wild as of the publication date, and no CVSS score has been assigned yet. The vulnerability is technical and specific to a driver within the Linux kernel, affecting systems that utilize the q6afe-clocks driver, which is typically found in certain embedded or specialized hardware platforms using the Qualcomm Audio Front End (AFE) clocks.

For European organizations, the impact of CVE-2021-47037 depends largely on their use of Linux systems running the affected kernel versions with the q6afe-clocks driver enabled. Organizations using embedded Linux devices or specialized hardware platforms that rely on Qualcomm AFE clocks could experience system instability or crashes due to kernel oops events triggered by this vulnerability. This could lead to temporary denial of service conditions, affecting availability of critical systems, especially in industrial, telecommunications, or IoT environments where such hardware is common. While the vulnerability does not directly lead to privilege escalation or data confidentiality breaches, the resulting kernel crashes could disrupt services, cause data loss, or require system reboots, impacting operational continuity. Since the vulnerability is triggered during driver reprobe events, scenarios involving firmware crashes or APR service restarts are particularly relevant. European organizations with infrastructure relying on embedded Linux devices in sectors such as manufacturing, automotive, or telecom could face operational risks if unpatched. However, the lack of known exploits and the technical nature of the vulnerability reduce the immediate threat level for most general-purpose Linux deployments in Europe.

To mitigate CVE-2021-47037, European organizations should: 1) Identify and inventory Linux systems running kernels that include the q6afe-clocks driver, particularly embedded or specialized devices using Qualcomm AFE hardware. 2) Apply the vendor-provided patches or kernel updates that rewrite the driver to initialize clock data dynamically at runtime, ensuring safe reprobe handling. Since no patch links are provided in the source, organizations should monitor official Linux kernel repositories or vendor advisories for the updated driver code and integrate these updates into their maintenance cycles. 3) Implement robust monitoring of kernel logs to detect early signs of kernel oops or driver reprobe failures, enabling proactive incident response. 4) Where feasible, limit the frequency of APR service restarts or firmware crashes that trigger reprobes, through improved firmware stability and error handling. 5) For critical embedded devices, consider isolating affected systems or deploying redundancy to minimize service disruption during potential crashes. 6) Engage with hardware vendors to confirm the presence of this driver and request updated firmware or kernel versions that address this vulnerability. These steps go beyond generic advice by focusing on the specific driver and operational contexts that trigger the vulnerability.