CVE-2024-36930 is a vulnerability identified in the Linux kernel's SPI (Serial Peripheral Interface) subsystem, specifically within the spi_sync() function. The issue arises when spi_sync() is called with a non-empty queue and the same spi_message structure is reused without properly clearing the complete callback pointer. The vulnerability is a null pointer dereference triggered during the invocation of the callback from spi_finalize_current_message(). This occurs because the callback pointer remains set while the context it relies on has been cleared, leading to a dereference of a null pointer. The problem is rooted in the failure to reset the message->complete pointer to NULL after the transfer completes. The call stack provided shows the sequence of kernel functions involved, culminating in the callback invocation that triggers the fault. The vulnerability can cause a kernel crash (denial of service) due to the null pointer dereference. The fix involves explicitly setting the message->complete pointer to NULL once the transfer is complete, preventing the callback from being invoked with an invalid context. This vulnerability affects Linux kernel versions identified by the commit hashes provided, and it is relevant to systems using SPI devices, which are common in embedded systems, IoT devices, and some industrial control systems. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the primary impact of CVE-2024-36930 is the potential for denial of service (DoS) on Linux-based systems that utilize SPI devices. This includes embedded systems, industrial automation equipment, networking hardware, and IoT devices that run Linux kernels vulnerable to this issue. A successful exploitation could cause kernel crashes, leading to system reboots or failures, disrupting critical services or industrial processes. While this vulnerability does not directly lead to privilege escalation or remote code execution, the resulting instability can affect availability and operational continuity. Organizations in sectors such as manufacturing, telecommunications, automotive, and critical infrastructure that rely on Linux-based embedded systems are particularly at risk. The disruption could also impact supply chains and operational technology environments, which are prevalent in European industries. Since the vulnerability requires kernel-level interaction with SPI devices, the attack surface is somewhat limited to systems with such hardware interfaces, but the widespread use of Linux in embedded and industrial contexts in Europe means the risk is non-negligible.

1. Apply Kernel Updates: European organizations should prioritize applying the official Linux kernel patches that address CVE-2024-36930 as soon as they become available from their Linux distribution vendors or directly from the Linux kernel source. 2. Audit SPI Device Usage: Conduct an inventory of systems using SPI devices and assess whether they run vulnerable kernel versions. 3. Limit Access to SPI Interfaces: Restrict access to SPI device interfaces to trusted processes and users only, minimizing the risk of malicious or accidental invocation of spi_sync() with problematic parameters. 4. Kernel Hardening: Employ kernel hardening techniques such as kernel lockdown modes, SELinux/AppArmor policies, and secure boot to reduce the risk of exploitation and unauthorized kernel interactions. 5. Monitoring and Logging: Implement enhanced monitoring of kernel logs and system stability metrics to detect abnormal crashes or reboots potentially related to this vulnerability. 6. Test Updates in Controlled Environments: Before wide deployment, test kernel updates in staging environments to ensure compatibility with existing SPI device drivers and applications. 7. Vendor Coordination: For embedded or industrial devices, coordinate with hardware and software vendors to ensure timely firmware and kernel updates are provided and applied.