CVE-2024-56766 is a vulnerability identified in the Linux kernel's Memory Technology Device (MTD) subsystem, specifically within the raw NAND driver for Atmel devices (atmel_pmecc). The flaw arises from improper memory management where a 'user' pointer, originally allocated with kzalloc(), was changed to be allocated using devm_kzalloc(). The devm_kzalloc() function is managed by the device's lifecycle and automatically frees the allocated memory when the device is detached or the driver is unloaded. However, the code still explicitly calls kfree(user), which leads to a double free condition. A double free occurs when the same memory is freed more than once, which can corrupt the kernel's memory allocator state. This corruption can potentially be exploited by an attacker to execute arbitrary code with kernel privileges, cause a denial of service (system crash), or escalate privileges. The vulnerability affects multiple Linux kernel versions identified by specific commit hashes, indicating it is present in various recent kernel builds. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability was publicly disclosed on January 6, 2025, and the fix involves correcting the memory allocation and deallocation logic to prevent the double free scenario.

For European organizations, the impact of CVE-2024-56766 can be significant, especially for those relying on Linux-based systems in critical infrastructure, embedded devices, or servers that utilize the affected raw NAND driver. Exploitation could allow attackers to gain kernel-level code execution, leading to full system compromise, data breaches, or persistent malware installation. This is particularly concerning for sectors such as telecommunications, manufacturing, automotive, and IoT device manufacturers, where Atmel NAND flash memory might be used. Additionally, denial of service attacks could disrupt services and operations, impacting business continuity. Since Linux is widely deployed across Europe in enterprise, government, and industrial environments, the vulnerability poses a broad risk. However, the absence of known exploits and the requirement for specific hardware and kernel configurations may limit immediate widespread exploitation. Still, proactive patching is critical to prevent potential future attacks.

1. Immediate application of the official Linux kernel patches that address the double free in atmel_pmecc_create_user() is essential. Organizations should track kernel updates from their Linux distribution vendors and apply them promptly. 2. For embedded and IoT devices using custom or older Linux kernels, vendors should backport the fix or upgrade the kernel to a secure version. 3. Conduct an inventory of systems using Atmel raw NAND devices and assess exposure to this vulnerability. 4. Implement kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Kernel Page Table Isolation (KPTI) to reduce exploitation risk. 5. Employ runtime security monitoring tools that can detect anomalous kernel memory operations or crashes indicative of exploitation attempts. 6. Restrict access to systems with vulnerable kernels, especially limiting untrusted user access and network exposure. 7. Engage in regular security audits and penetration testing focusing on kernel vulnerabilities to identify potential exploitation paths. 8. Maintain robust backup and recovery procedures to mitigate impact in case of successful exploitation.