CVE-2024-26785 is a medium-severity vulnerability in the Linux kernel's iommufd subsystem, specifically related to the handling of I/O memory management unit (IOMMU) file descriptors. The vulnerability arises from a race condition in the function iommufd_access_change_ioas(), which sets the access->ioas pointer to NULL during its operation. This can lead to a protection fault due to a null pointer dereference when concurrent access occurs, as the lock protecting this pointer might be released prematurely. The issue was identified by the Syzkaller fuzzing tool, which triggered a general protection fault caused by a non-canonical address access and a null pointer dereference detected by Kernel Address Sanitizer (KASAN). The root cause is a lack of proper sanity checks on the access->ioas pointer in the affected function, unlike other similar functions such as iommufd_access_rw() and iommufd_access_pin_pages() that perform these checks. Exploitation of this vulnerability can cause a denial of service (DoS) by crashing the kernel due to the protection fault, impacting system availability. The vulnerability requires local privileges (PR:L) and does not require user interaction (UI:N), with low attack complexity (AC:L) and local attack vector (AV:L). No confidentiality or integrity impact is expected, but availability is affected. No known exploits are currently reported in the wild. The vulnerability affects Linux kernel versions identified by the commit hash 9227da7816dd1a42e20d41e2244cb63c205477ca and likely other versions containing the vulnerable code before the patch. The fix involves adding proper sanity checks on the access->ioas pointer to prevent dereferencing NULL and ensuring locks are correctly held during concurrent operations.

For European organizations, this vulnerability primarily poses a risk of denial of service on Linux systems that utilize the iommufd subsystem, which is relevant in environments using advanced IOMMU features for device isolation and virtualization. Organizations running Linux servers, especially those in data centers, cloud infrastructure, or with virtualization workloads, may experience kernel crashes leading to service interruptions. While the vulnerability does not expose sensitive data or allow privilege escalation, the availability impact can disrupt critical services, affecting business continuity. Given the local attack vector and requirement for local privileges, the threat is more significant in multi-tenant environments or where untrusted users have shell access. European organizations with strict uptime requirements, such as financial institutions, healthcare providers, and critical infrastructure operators, should prioritize patching to avoid potential operational disruptions. The absence of known exploits reduces immediate risk but does not eliminate the need for mitigation, as attackers could develop exploits given the public disclosure.

1. Apply the official Linux kernel patch that addresses CVE-2024-26785 as soon as it becomes available from trusted sources or Linux distribution vendors. 2. For environments where immediate patching is not feasible, restrict local user access to systems running vulnerable Linux kernel versions, minimizing the risk of local exploitation. 3. Implement strict access controls and monitoring on systems with IOMMU features enabled, especially those exposing iommufd interfaces. 4. Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar issues proactively. 5. Maintain up-to-date inventory of Linux kernel versions deployed across the organization to identify and prioritize vulnerable systems. 6. Use virtualization and container isolation best practices to limit the impact of potential kernel crashes. 7. Monitor system logs for unusual kernel faults or crashes that could indicate exploitation attempts.