CVE-2024-42149 is a vulnerability identified in the Linux kernel's filesystem block device freeze and thaw operations. The issue arises from a race condition involving concurrent operations on a block device that is frozen but not yet claimed by a filesystem. Specifically, the vulnerability occurs when one process (P1) suspends the device by freezing it (incrementing the freeze count) before the filesystem claims it, while another process (P2) attempts to mount the frozen block device and temporarily claims it. Concurrently, a third process (P3) resumes the device and calls the thaw operation. Due to the timing and state management, P3 may take a passive reference to the filesystem, find it not ready, and sleep waiting for readiness. Meanwhile, P2 may release the last active reference and mark the filesystem as dying. When P3 wakes, it finds the filesystem dying, causing get_bdev_super() to fail. This sequence can lead to misleading warnings during thaw operations and potentially unstable filesystem states. Although the description does not explicitly mention direct exploitation or data corruption, the race condition and improper state handling could cause mount failures, filesystem unavailability, or unexpected behavior during device freeze/thaw cycles. The vulnerability affects Linux kernel versions identified by the commit hash 49ef8832fb1a9e0da0020eb17480fd286433bc13. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability could impact systems relying on Linux kernels with the affected versions, particularly those using block device freeze and thaw operations in environments with dynamic device management, such as virtualized infrastructures, container platforms, or storage appliances. The potential impact includes temporary filesystem unavailability, failed mount operations, or system instability during device suspension and resumption cycles. This could disrupt critical services, especially in data centers or cloud environments where Linux is prevalent. While no direct data corruption or privilege escalation is indicated, the failure to mount filesystems or unexpected filesystem states could lead to operational downtime, affecting business continuity. Organizations with automated device management or complex storage setups might experience increased risk of service interruptions. The absence of known exploits reduces immediate risk, but the complexity of the issue warrants timely patching to prevent future exploitation or operational issues.

To mitigate this vulnerability, European organizations should: 1) Identify and inventory Linux systems running kernel versions including or derived from the affected commit (49ef8832fb1a9e0da0020eb17480fd286433bc13). 2) Apply the official Linux kernel patches that address this race condition as soon as they become available from trusted sources or distributions. 3) In environments where immediate patching is not feasible, minimize concurrent freeze/thaw and mount operations on block devices, especially during device suspension or resumption workflows. 4) Implement monitoring to detect unusual mount failures or filesystem state warnings that could indicate triggering of this issue. 5) For critical systems, consider testing patches in staging environments to ensure stability before production deployment. 6) Coordinate with Linux distribution vendors for backported fixes and security advisories. 7) Review and harden device management automation scripts to avoid overlapping freeze/thaw and mount operations that could trigger the race condition.