CVE-2022-49379 is a vulnerability in the Linux kernel related to the handling of deferred device probing during system boot. The issue arises from the interaction between the wait_for_device_probe() function and the deferred_probe_timeout mechanism. Deferred probing is a kernel feature that delays the initialization of certain devices until required resources or conditions are met, often to allow userspace modules to load. The vulnerability manifests when mounting an NFS root filesystem times out due to ip_auto_config() waiting indefinitely for network interfaces to become available. This happens because wait_for_device_probe() does not properly wait for the deferred_probe_timeout to expire, causing a deadlock or prolonged blocking in the kernel_init() context. A prior fix attempted to ensure wait_for_device_probe() waits for the deferred_probe_timeout, but this introduced two critical issues: if called before deferred_probe_initcall(), it causes a boot hang due to deadlock; if called after, it blocks kernel_init() until the timeout expires, defeating the purpose of deferred probing. Consequently, the problematic changes were reverted, leaving the underlying timing and synchronization issues unresolved. This vulnerability can cause system boot failures or significant delays, particularly when using network-based root filesystems like NFS. Although no known exploits are reported, the flaw affects the core Linux kernel driver initialization process and can impact system availability during boot.

For European organizations relying on Linux-based infrastructure, especially those using network booting or NFS root filesystems, this vulnerability can lead to system boot failures or extended downtime. Critical systems such as servers, embedded devices, or network appliances that depend on deferred probing for device initialization may experience hangs or delays, impacting availability and operational continuity. This is particularly relevant for industries with stringent uptime requirements like telecommunications, finance, healthcare, and manufacturing. The inability to boot or delayed boot processes can disrupt services, delay deployments, and increase operational costs. While confidentiality and integrity are not directly impacted, the availability degradation during boot can have cascading effects on business-critical applications and services. Since the vulnerability affects the Linux kernel itself, it has a broad potential impact across various distributions and hardware platforms used in Europe.

Organizations should monitor Linux kernel updates and apply patches once a stable fix addressing this deferred probe timing issue is released. In the interim, system administrators can mitigate risk by avoiding configurations that rely on deferred probing with non-zero deferred_probe_timeout values, particularly for network root filesystems like NFS. Testing boot sequences in controlled environments before deployment can help identify if the issue affects specific hardware or kernel versions. Additionally, consider alternative boot methods that do not depend on deferred probing or adjust kernel parameters to minimize deferred_probe_timeout delays. Collaborating with Linux distribution maintainers to track backported fixes and applying vendor-specific patches promptly is critical. For embedded or specialized devices, firmware or kernel customization may be necessary to circumvent the problematic code paths. Maintaining robust backup and recovery procedures ensures rapid restoration if boot failures occur.