CVE-2023-53084 is a vulnerability identified in the Linux kernel, specifically within the Direct Rendering Manager (DRM) subsystem's shared memory helper code. The flaw arises in the drm_gem_shmem_mmap() function, which handles memory mapping of shared memory GEM (Graphics Execution Manager) objects used for DMA-buf (Direct Memory Access buffer) operations. The vulnerability is due to an erroneous reference count decrement (put) in an error handling path, which causes the shared memory GEM object to be prematurely freed. This premature freeing leads to a use-after-free condition, where subsequent operations may access memory that has already been released. Such use-after-free bugs can lead to undefined behavior including system crashes, data corruption, or potentially arbitrary code execution if exploited. The issue was caused by a missing ownership of the reference in the error code path, and the fix involved removing the errant put call to ensure proper reference counting and memory management. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in recent kernel builds prior to the patch. No known exploits are reported in the wild as of the publication date. The vulnerability does not have an assigned CVSS score yet, and no additional CWE identifiers or patch links were provided.

For European organizations, this vulnerability poses a risk primarily to systems running affected Linux kernel versions with the DRM subsystem enabled, which is common in servers, desktops, and embedded devices that utilize GPU acceleration or graphics-related operations. Exploitation could lead to system instability or crashes, impacting availability of critical services. In more severe scenarios, attackers might leverage the use-after-free to execute arbitrary code with kernel privileges, compromising confidentiality and integrity of data and systems. This is particularly concerning for organizations relying on Linux-based infrastructure for sensitive workloads, including cloud providers, financial institutions, research centers, and government agencies. The lack of known exploits reduces immediate risk, but the vulnerability's presence in widely deployed Linux kernels means that targeted attacks could emerge. Additionally, the complexity of exploiting kernel use-after-free bugs may limit widespread exploitation but does not eliminate risk for high-value targets. The vulnerability could also affect embedded Linux devices used in industrial control systems or telecommunications, which are critical for European infrastructure.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched. Since the vulnerability is related to specific commits, applying the latest stable kernel releases from trusted sources or vendor-provided security updates is essential. For environments where immediate patching is not feasible, organizations should restrict access to systems running vulnerable kernels, especially limiting untrusted user access and network exposure. Monitoring kernel logs for unusual crashes or memory errors related to DRM or GEM subsystems can help detect exploitation attempts. Employing kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR), Control Flow Integrity (CFI), and enabling security modules like SELinux or AppArmor can reduce exploitation likelihood. For embedded devices, coordinate with vendors to obtain firmware updates or mitigations. Finally, maintain an inventory of Linux systems and their kernel versions to ensure timely patch management and vulnerability tracking.