CVE-2024-40967 is a vulnerability identified in the Linux kernel specifically affecting the serial driver for the i.MX platform. The issue arises from the handling of the transmitter empty state (USR2_TXDC) in the serial communication driver. Previously, the kernel code would wait indefinitely for the transmitter to signal that it was empty before proceeding, which could lead to a deadlock situation if the signal was never set. The fix introduces a timeout mechanism, waiting at most one second for the USR2_TXDC flag to be set. If the timeout expires without the flag being set, the driver ignores the transmitter state and continues operation optimistically. This change prevents the system from hanging due to the deadlock but may result in some loss of transmission state accuracy. The vulnerability is rooted in the kernel's serial communication subsystem for i.MX devices, which are commonly used in embedded systems and specialized hardware. No known exploits are currently reported in the wild, and the fix involves a relatively straightforward timeout addition to the driver code. The vulnerability does not have an assigned CVSS score yet, and the affected versions are identified by specific git commit hashes, indicating it affects certain recent kernel builds incorporating the vulnerable serial driver code.

For European organizations, the impact of this vulnerability depends largely on the deployment of Linux systems running on i.MX hardware platforms. These platforms are often found in embedded devices, industrial control systems, IoT devices, and specialized communication equipment. A deadlock in the serial driver could cause system hangs or unresponsiveness, potentially disrupting critical operations in industrial environments, manufacturing plants, or network infrastructure relying on such devices. While this vulnerability does not directly lead to privilege escalation or data leakage, the availability impact could be significant in operational technology (OT) environments where uptime is critical. The optimistic continuation after timeout may also cause subtle communication errors, potentially affecting data integrity in serial communications. Since no known exploits exist yet, the immediate risk is low, but organizations using affected hardware should prioritize patching to avoid potential denial-of-service conditions that could be exploited or triggered inadvertently.

European organizations should take the following specific steps: 1) Identify all Linux systems running on i.MX platforms or using the affected serial driver. This includes embedded devices, industrial controllers, and IoT equipment. 2) Apply the kernel patch that introduces the timeout mechanism as soon as it becomes available in their Linux distribution or vendor firmware updates. 3) For devices where patching is not immediately feasible, implement monitoring to detect serial communication hangs or system unresponsiveness that could indicate triggering of this vulnerability. 4) Engage with hardware and software vendors to confirm the presence of the fix in firmware or kernel updates. 5) Where possible, isolate critical embedded systems from public or untrusted networks to reduce the risk of remote triggering of the deadlock. 6) Conduct thorough testing after patching to ensure that the timeout does not introduce unexpected communication errors in critical systems.