CVE-2024-47709 addresses a vulnerability in the Linux kernel's CAN (Controller Area Network) BCM (Broadcast Manager) subsystem. The issue arises from improper handling of the bcm_proc_read pointer after the removal of a proc filesystem entry via remove_proc_entry(). Specifically, a previous fix intended to address warnings triggered when a connect() call is issued again on a socket whose connected device has been unregistered inadvertently introduced a new problem. If the socket is closed without a second connect() call, the bcm_proc_read pointer remains uncleared, causing an unnecessary invocation of remove_proc_entry() during bcm_release(). This can lead to a kernel warning or potentially undefined behavior due to double removal or use-after-free conditions in the proc filesystem interface. The vulnerability was reported by syzbot, an automated kernel fuzzer, which detected warnings during bcm_release(). The fix involves explicitly clearing the bcm_proc_read pointer after remove_proc_entry() in the bcm_notify() function to prevent repeated removal attempts. This vulnerability affects multiple Linux kernel versions, including recent mainline releases, as indicated by the affected commit hashes. While no known exploits are reported in the wild, the flaw could cause kernel instability or denial of service (DoS) through kernel warnings or crashes triggered by socket operations on CAN BCM sockets. The vulnerability does not appear to allow privilege escalation or arbitrary code execution directly but may impact system availability and reliability, especially on systems utilizing CAN BCM sockets for communication.

For European organizations, the impact of CVE-2024-47709 primarily concerns systems that use Linux kernels with CAN BCM support, which is common in embedded systems, automotive, industrial control, and IoT devices. Organizations in sectors such as automotive manufacturing, industrial automation, transportation, and critical infrastructure may be affected if their Linux-based systems rely on CAN BCM sockets. The vulnerability could lead to kernel warnings or crashes, resulting in denial of service conditions that disrupt operations or degrade system reliability. In safety-critical environments, such as automotive or industrial control systems, unexpected kernel faults could have cascading effects on operational safety and availability. Although no direct exploitation for privilege escalation is known, the potential for system instability necessitates prompt patching to maintain operational continuity. European organizations with Linux-based infrastructure, especially those deploying custom or embedded Linux kernels with CAN support, should assess their exposure and prioritize remediation to avoid service interruptions or safety risks.

1. Apply the official Linux kernel patches that address CVE-2024-47709 as soon as they become available from trusted sources or Linux distribution vendors. 2. For embedded or custom Linux systems, rebuild and deploy updated kernel versions incorporating the fix. 3. Audit systems using CAN BCM sockets to identify those potentially affected, focusing on automotive, industrial, and IoT devices. 4. Implement monitoring for kernel warnings or unusual socket behavior related to CAN BCM to detect potential exploitation or instability. 5. Limit access to CAN BCM socket interfaces to trusted processes and users to reduce the risk of triggering the vulnerability. 6. In environments where patching is delayed, consider temporary mitigations such as disabling CAN BCM socket usage if feasible, or isolating affected systems to minimize impact. 7. Maintain up-to-date kernel versions and subscribe to security advisories from Linux kernel maintainers and distribution vendors to promptly address similar vulnerabilities.