CVE-2024-50006 is a vulnerability identified in the Linux kernel's ext4 filesystem implementation, specifically related to the ext4_ind_migrate() function. The issue arises from an incorrect unlock order of the i_data_sem semaphore, which can lead to a potential deadlock scenario involving the journaling layer (jbd2). The vulnerability is triggered when the EXT4_IOC_MIGRATE ioctl is invoked with synchronous updates required (i.e., the file descriptor is opened with the O_SYNC flag). Under these conditions, the jbd2_journal_stop() function may call jbd2_might_wait_for_commit(), which attempts to lock the jbd2_handle while i_data_sem is already held. This lock ordering conflict can cause a deadlock if the EXT4_IOC_MIGRATE ioctl races with a concurrent write(2) system call. Notably, this problem only manifests when the kernel is compiled with CONFIG_PROVE_LOCKING enabled, a debugging feature that enforces strict lock dependency checks. The vulnerability was discovered through fuzz testing by the Linux Verification Center using syzkaller. Although no known exploits are currently reported in the wild, the issue represents a kernel-level synchronization flaw that could impact system stability and availability. The affected versions are identified by a specific commit hash, indicating the vulnerability is present in certain recent kernel builds prior to the fix. No CVSS score has been assigned yet.

For European organizations, this vulnerability primarily threatens system availability and stability rather than confidentiality or integrity. Systems running Linux kernels compiled with CONFIG_PROVE_LOCKING enabled and using ext4 filesystems with synchronous IO operations are at risk of deadlocks, which can cause processes to hang or the system to become unresponsive. This is particularly critical for servers and infrastructure handling high IO workloads or synchronous file operations, such as database servers, file servers, and critical application hosts. In environments where uptime and reliability are paramount—such as financial institutions, healthcare providers, and public sector organizations—such deadlocks could lead to service disruptions, operational delays, and potential data loss if processes are forcibly terminated. Although exploitation requires specific conditions (CONFIG_PROVE_LOCKING enabled, use of EXT4_IOC_MIGRATE ioctl with O_SYNC), the presence of this vulnerability in Linux kernels used widely across European data centers and enterprises means that unpatched systems could face stability risks. The lack of known exploits reduces immediate threat but does not eliminate the risk of future exploitation or accidental triggering in complex workloads.

1. Apply Kernel Updates: European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched. Monitoring vendor advisories and Linux kernel mailing lists for official patches is essential. 2. Review Kernel Configuration: Since the vulnerability only manifests when CONFIG_PROVE_LOCKING is enabled, organizations that do not require this debugging feature should consider disabling it in their kernel builds to reduce exposure. 3. Limit Use of EXT4_IOC_MIGRATE ioctl with O_SYNC: Evaluate and restrict the use of the EXT4_IOC_MIGRATE ioctl with synchronous flags in production environments, especially on critical systems. 4. Implement Robust Monitoring: Deploy monitoring solutions to detect unusual process hangs or deadlocks related to ext4 filesystem operations, enabling rapid response to potential incidents. 5. Test Updates in Staging: Before deploying kernel updates broadly, conduct thorough testing in staging environments to ensure compatibility and stability, particularly for workloads involving synchronous IO and ext4 migrations. 6. Backup Critical Data: Maintain up-to-date backups to mitigate risks associated with forced reboots or system crashes resulting from deadlocks. 7. Engage with Vendors: For commercial Linux distributions, coordinate with vendors for timely patches and support tailored to specific kernel versions in use.