CVE-2021-47051 is a vulnerability identified in the Linux kernel specifically affecting the Freescale Low Power SPI (lpspi) driver component. The issue arises from improper handling of power management runtime (pm_runtime) reference counting within the function lpspi_prepare_xfer_hardware(). The vulnerability is caused by the use of pm_runtime_get_sync(), which increments the power management usage counter even when it fails, leading to an imbalance in the reference count. This results in a reference leak where the usage counter is not properly decremented, potentially causing the device to remain in an unintended power state. The fix replaces pm_runtime_get_sync() with pm_runtime_resume_and_get(), which ensures the usage counter remains balanced by correctly handling the increment only when the operation succeeds. Although this vulnerability does not directly lead to remote code execution or privilege escalation, the improper power management reference counting can cause resource leaks and potentially degrade system stability or availability over time. The vulnerability affects specific versions of the Linux kernel source code as identified by the commit hashes provided. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet. The issue is primarily a resource management bug within the kernel's SPI driver power management subsystem.

For European organizations, the impact of CVE-2021-47051 is primarily related to system stability and availability rather than direct compromise of confidentiality or integrity. Systems running affected Linux kernel versions with the Freescale lpspi driver enabled may experience power management reference leaks, which could lead to devices or subsystems failing to enter low-power states correctly. Over time, this can cause increased power consumption, reduced battery life on embedded or mobile devices, and potential system instability or crashes. Organizations relying on embedded Linux systems, industrial control systems, or IoT devices using affected kernels may face operational disruptions. While no direct exploitation is known, the vulnerability could be leveraged in complex attack chains to degrade system reliability or cause denial-of-service conditions. The impact is more pronounced in environments where power efficiency and system uptime are critical, such as telecommunications infrastructure, manufacturing automation, and critical embedded systems prevalent in European industries.

To mitigate CVE-2021-47051, organizations should apply the official Linux kernel patches that replace pm_runtime_get_sync() with pm_runtime_resume_and_get() in the lpspi driver code. This ensures proper reference counting and prevents the power management leak. Specifically, maintainers and system integrators should update to the latest stable kernel releases that include this fix. For embedded and IoT devices, firmware updates incorporating the patched kernel should be deployed promptly. Additionally, organizations should audit their Linux kernel versions and configurations to identify systems using the affected lpspi driver. Monitoring power consumption and system logs for anomalies related to power management can help detect potential issues early. Where possible, implement kernel runtime verification tools to detect reference counting anomalies. Finally, ensure that device manufacturers and vendors are informed to provide updated firmware or kernel versions to end users.