CVE-2024-56621 is a vulnerability identified in the Linux kernel's SCSI UFS (Universal Flash Storage) core driver. The issue arises because the Real-Time Clock (RTC) work queue is not properly cancelled during the removal of the UFS host controller driver (ufshcd_remove()). While RTC work cancellation occurs during the suspend operation (__ufshcd_wl_suspend()), it is omitted during the removal process. This omission can lead to a use-after-free or NULL pointer dereference when the RTC work queue attempts to access internal ufshcd structures that have already been freed or invalidated. The kernel logs indicate a NULL pointer dereference at a low virtual address (0x2a4), which causes a kernel panic or crash. The call trace shows the fault occurring in the ufshcd_rtc_work function, triggered by the workqueue system. Since the RTC work accesses internal data structures of the ufshcd driver, failing to cancel this work during removal leads to unsafe memory access. The fix involves cancelling the RTC work explicitly in the ufshcd_remove() function, aligning with the initialization and suspend order to ensure safe cleanup. This vulnerability affects specific Linux kernel versions identified by commit hashes, and no known exploits have been reported in the wild as of the publication date (December 27, 2024). No CVSS score has been assigned yet.

For European organizations, this vulnerability primarily poses a risk of denial of service (DoS) through kernel crashes on systems using affected Linux kernel versions with UFS storage devices. The kernel panic caused by the NULL pointer dereference can lead to system instability, unexpected reboots, and potential data loss if critical processes are interrupted. This is particularly relevant for enterprises relying on embedded Linux systems, mobile devices, or servers that utilize UFS storage technology. Although this vulnerability does not directly expose confidentiality or integrity risks, the availability impact can disrupt business operations, especially in environments requiring high uptime such as telecommunications, industrial control systems, and cloud infrastructure providers. The absence of known exploits reduces immediate threat levels, but unpatched systems remain vulnerable to accidental or targeted triggering of the flaw. Organizations in Europe with Linux-based infrastructure should be aware of this risk, especially those deploying custom or older kernel versions where backported fixes may not yet be applied.

European organizations should prioritize updating their Linux kernel to versions that include the patch for CVE-2024-56621. Since the vulnerability involves kernel-level code, applying vendor-provided kernel updates or mainline Linux kernel patches is the most effective mitigation. For environments where immediate patching is not feasible, administrators should consider disabling or limiting the use of UFS devices or the ufshcd driver if possible, to reduce exposure. Monitoring kernel logs for messages related to ufshcd_rtc_work or kernel NULL pointer dereferences can help detect attempts to trigger the vulnerability. Additionally, implementing robust system monitoring and automated reboot mechanisms can mitigate downtime caused by unexpected crashes. For embedded or specialized systems, coordinate with hardware and OS vendors to obtain timely patches. Finally, ensure that system backups and recovery procedures are tested and in place to minimize data loss from potential crashes.