CVE-2021-47499 is a vulnerability identified in the Linux kernel specifically within the Industrial I/O (IIO) subsystem's accelerometer driver for the kxcjk-1013 sensor. The issue arises when the ACPI (Advanced Configuration and Power Interface) type is ACPI_SMO8500. Under this condition, the data structure member 'dready_trig' is not set during the driver's probe function. This omission leads to a failure to free memory allocated by the function iio_triggered_buffer_setup(), resulting in a memory leak. The vulnerability is characterized by unreferenced kernel memory objects, which accumulate over time as the driver repeatedly allocates memory without releasing it. The technical root cause is the conditional check on data->dready_trig in the probe and remove functions, which was removed in the patch to ensure proper cleanup. The memory leak is demonstrated by kernel debug information showing unreferenced objects and a backtrace through kernel functions such as kmem_cache_alloc_trace, iio_kfifo_allocate, and kxcjk1013_probe. This vulnerability does not appear to have known exploits in the wild and does not have an assigned CVSS score. However, it affects Linux kernel versions identified by the commit hash a25691c1f9674090fb66586cf4c5d60d3efdf339 and potentially others in the same code lineage. The flaw is primarily a resource management bug that could lead to gradual degradation of system stability or denial of service due to kernel memory exhaustion if the vulnerable driver is repeatedly probed or used under the specified ACPI condition.

For European organizations, the impact of CVE-2021-47499 is primarily related to system reliability and availability. Systems running Linux kernels with the vulnerable kxcjk-1013 accelerometer driver and configured with ACPI_SMO8500 devices may experience memory leaks that degrade performance over time, potentially leading to kernel crashes or system reboots. This can affect embedded systems, industrial control devices, or IoT devices that rely on this specific sensor driver, especially in sectors such as manufacturing, automotive, or critical infrastructure where Linux is commonly used in embedded environments. While the vulnerability does not directly expose confidentiality or integrity risks, the availability impact could disrupt operations, cause downtime, or require unscheduled maintenance. Since no known exploits exist, the immediate risk is low, but unpatched systems remain vulnerable to stability issues. European organizations with extensive Linux deployments in industrial or embedded contexts should be aware of this risk, as it could affect operational technology (OT) environments and critical systems that depend on continuous uptime.

To mitigate CVE-2021-47499, organizations should: 1) Apply the official Linux kernel patches that remove the conditional check on data->dready_trig in the probe and remove functions of the kxcjk-1013 driver, ensuring proper memory cleanup. 2) Update Linux kernel versions to those including the fix, ideally from the vendor or distribution maintainers providing patched kernel releases. 3) Audit systems to identify devices using the kxcjk-1013 accelerometer driver and verify if the ACPI_SMO8500 type is present, prioritizing updates on affected devices. 4) Monitor system logs and kernel memory usage for signs of memory leaks or instability related to the IIO subsystem. 5) For embedded or industrial devices where kernel updates are challenging, consider workarounds such as disabling the affected driver if not required or isolating vulnerable devices from critical networks. 6) Implement robust system monitoring and automated reboot policies to mitigate impact from potential memory exhaustion until patches can be applied. These steps go beyond generic advice by focusing on device-specific identification, patch application, and operational monitoring tailored to the nature of this kernel memory leak.