CVE-2024-46851 is a race condition vulnerability identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the AMD display driver code (dcn10_set_drr and dc_state_destruct functions). The vulnerability arises due to a timing issue between the dc_state_destruct() function, which nullifies the resource context of the display controller (DC) state, and the dcn10_set_drr() function, which accesses members of this resource context during interrupt request (IRQ) processing. If dc_state_destruct() is invoked concurrently with IRQ processing, dcn10_set_drr() may attempt to access already nulled function callback fields of the stream_resource structure, leading to use-after-null pointer dereferences. The existing mitigation in dcn10_set_drr() checks if the timing generator (tg) pointer is NULL before use, but a race condition can still occur if the pointer is nulled immediately after this check and before subsequent accesses. The fix involves copying the tg pointer to a local variable before use, ensuring consistent access during the function execution, assuming the resource pool containing the timing generators is not freed concurrently. This vulnerability is rooted in improper synchronization and concurrent access handling in the AMD display driver code within the Linux kernel. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects specific Linux kernel versions identified by commit hashes, and the patch has been integrated into the kernel source to prevent this race condition.

For European organizations relying on Linux-based systems with AMD graphics hardware, this vulnerability could lead to system instability or crashes due to the race condition in the display driver. Although no direct remote code execution or privilege escalation is indicated, the use-after-null pointer dereference could be exploited to cause denial of service (DoS) by crashing the kernel or triggering unexpected behavior in the display subsystem. This may impact critical infrastructure, enterprise servers, or workstations running Linux with AMD GPUs, especially in sectors like finance, manufacturing, or government where Linux is prevalent. The vulnerability's impact on confidentiality and integrity appears limited, but availability could be affected due to potential system crashes or hangs. Since the flaw occurs during IRQ handling, it could be triggered by local processes or drivers interacting with the display hardware, requiring local access or user interaction. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to maintain system stability and prevent potential escalation by attackers combining this flaw with other vulnerabilities.

European organizations should promptly apply the official Linux kernel patches that address CVE-2024-46851 once available in their distribution updates. Specifically, updating to the latest stable kernel versions containing the fix is critical. For environments where immediate patching is not feasible, organizations can mitigate risk by limiting untrusted local user access and restricting the use of AMD GPU features that trigger the vulnerable code paths, if possible. Monitoring system logs for kernel errors related to DRM or AMD display drivers can help detect exploitation attempts or instability. Additionally, organizations should ensure that kernel modules and drivers are sourced from trusted repositories and verify kernel integrity using tools like Linux Integrity Measurement Architecture (IMA). For critical systems, consider isolating or sandboxing graphical workloads to minimize impact. Regularly reviewing vendor advisories and subscribing to security mailing lists for Linux kernel updates will help maintain timely awareness of patches and related vulnerabilities.