CVE-2021-47165 is a vulnerability identified in the Linux kernel specifically within the Direct Rendering Manager (DRM) subsystem for Meson platforms. The issue arises in the shutdown sequence of the drm/meson driver when the main component, such as the dw-hdmi module, has not been probed or loaded yet, or is in a probe defer state. During system shutdown or reboot, the driver attempts to access a private data structure (priv struct) without verifying its allocation, leading to a NULL pointer dereference at a low virtual memory address (0x38). This results in a kernel crash, as evidenced by the call trace involving meson_drv_shutdown and platform_drv_shutdown functions. The root cause is the lack of a null check before using the priv struct during shutdown. The fix involves adding a check to ensure the priv struct is allocated before it is accessed, preventing the kernel from dereferencing a NULL pointer and crashing. This vulnerability affects certain Linux kernel versions identified by specific commit hashes, and it is related to ARM64 architecture platforms using the Meson DRM driver. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47165 primarily concerns systems running Linux kernels with the affected Meson DRM driver, which is common in embedded devices, ARM64-based platforms, and potentially some IoT devices. The vulnerability causes a denial of service (DoS) condition by crashing the kernel during shutdown or reboot sequences. This can lead to system instability, unexpected downtime, and potential disruption of critical services relying on affected devices. While the vulnerability does not appear to allow privilege escalation or remote code execution, the forced kernel crash can interrupt operations, especially in environments where uptime and reliability are critical, such as industrial control systems, telecommunications infrastructure, and embedded systems used in automotive or medical devices. European organizations deploying ARM64 Linux-based devices should be aware of this risk, as it could affect device lifecycle management and maintenance procedures. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or malicious triggering of the crash.

To mitigate CVE-2021-47165, organizations should: 1) Apply the latest Linux kernel patches that include the fix for this vulnerability, ensuring the Meson DRM driver properly checks for the allocation of the priv struct before accessing it during shutdown. 2) For embedded and ARM64-based devices, coordinate with hardware and software vendors to obtain updated firmware or kernel versions incorporating the fix. 3) Implement robust shutdown and reboot procedures that minimize the risk of triggering the vulnerability, such as ensuring dependent modules are properly loaded or unloaded in the correct order. 4) Monitor system logs for kernel crashes related to drm/meson or platform_drv_shutdown to detect potential occurrences of this issue. 5) In environments where patching is delayed, consider isolating affected devices or limiting their exposure to reduce the risk of accidental shutdown crashes. 6) Maintain an inventory of devices running affected Linux kernel versions to prioritize patching and risk assessment. These steps go beyond generic advice by focusing on the specific driver and platform affected and emphasizing operational controls alongside patch management.