CVE-2024-45028 is a vulnerability identified in the Linux kernel's MMC (MultiMediaCard) subsystem, specifically within the mmc_test module. The issue arises from improper handling of memory allocation failures. When the function alloc_pages() fails to allocate memory and returns NULL, the subsequent call to __free_pages() attempts to free this NULL pointer, leading to a NULL pointer dereference. This can cause a kernel panic or system crash, resulting in a denial of service (DoS) condition. Additionally, the error handling was flawed as it returned success instead of the appropriate -ENOMEM error code, which could mislead error detection mechanisms. The vulnerability is rooted in a lack of proper validation after memory allocation failure, which is a common programming oversight but critical in kernel space due to the potential for system-wide impact. The issue has been resolved by adding proper NULL checks before freeing memory and correcting the error code returned on allocation failure. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet. The vulnerability affects multiple versions of the Linux kernel as indicated by the repeated commit hashes, suggesting a widespread impact across kernel builds that include the vulnerable mmc_test code.

For European organizations, the primary impact of CVE-2024-45028 is the risk of denial of service due to kernel crashes triggered by the NULL pointer dereference. This can affect any Linux-based system utilizing the MMC subsystem, including servers, embedded devices, and workstations. Critical infrastructure sectors such as telecommunications, manufacturing, and public services that rely on Linux systems with MMC hardware could experience service interruptions. While this vulnerability does not directly lead to privilege escalation or remote code execution, the resulting instability can disrupt operations, cause data loss, or trigger failover mechanisms unnecessarily. Organizations using Linux distributions with kernels containing this vulnerability may face increased downtime and operational risk, especially if the MMC subsystem is actively used. The lack of known exploits reduces immediate risk, but the vulnerability's presence in kernel code means that attackers with local access could intentionally trigger crashes to disrupt services. This is particularly relevant for multi-tenant environments or systems exposed to untrusted users.

To mitigate CVE-2024-45028, European organizations should prioritize updating Linux kernels to versions where the patch fixing the NULL dereference in the mmc_test module has been applied. Kernel updates should be sourced from trusted distribution maintainers or directly from the Linux kernel mainline if custom kernels are used. Organizations should audit their systems to identify those running vulnerable kernel versions, especially those with MMC hardware or testing modules enabled. For systems where immediate patching is not feasible, disabling or unloading the mmc_test module can reduce exposure, although this may impact testing capabilities. Additionally, implementing robust monitoring for kernel panics and system crashes can help detect exploitation attempts or instability caused by this vulnerability. Security teams should also review access controls to limit local user privileges, reducing the risk of intentional triggering of the vulnerability. Finally, organizations should maintain regular backups and ensure failover systems are tested to minimize operational impact from potential crashes.