CVE-2024-39484 is a vulnerability identified in the Linux kernel specifically affecting the MMC (MultiMediaCard) driver for the DaVinci platform. The root cause lies in the improper use of the __exit macro on the driver's remove function. When the driver is built into the kernel (CONFIG_MMC_DAVINCI=y), the remove callback function is discarded during compilation because __exit marks functions to be discarded after initialization. Consequently, if the device is unbound dynamically (for example, via sysfs or hotplug mechanisms), the driver is removed without executing its cleanup routine. This leads to resource leaks such as unreleased memory or hardware resources. Additionally, this issue causes a section mismatch warning during module post-processing (modpost), indicating a code/data section inconsistency. The fix involves compiling the remove callback unconditionally, ensuring that the cleanup code is always present regardless of whether the driver is built-in or modular. This vulnerability does not appear to allow direct code execution or privilege escalation but can degrade system stability and reliability by leaking resources during device unbinding. No known exploits are reported in the wild at this time.

For European organizations, the impact of CVE-2024-39484 primarily concerns systems running Linux kernels with the DaVinci MMC driver built-in, which are typically embedded or specialized industrial devices rather than general-purpose servers or desktops. Resource leaks caused by the missing cleanup can accumulate over time, potentially leading to degraded device performance, system instability, or crashes. This can affect critical infrastructure or industrial control systems that rely on embedded Linux devices with MMC storage interfaces. While the vulnerability does not directly compromise confidentiality or integrity, availability may be impacted due to resource exhaustion or device malfunction. Organizations with embedded Linux deployments in sectors such as manufacturing, telecommunications, or transportation should be particularly attentive. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to maintain system reliability and prevent potential cascading failures in complex environments.

To mitigate this vulnerability, organizations should apply the official Linux kernel patch that removes the __exit annotation from the remove function in the DaVinci MMC driver, ensuring the cleanup code is always executed. This requires updating the kernel to a version that includes the fix or backporting the patch to custom kernel builds. For embedded systems where kernel updates are challenging, thorough testing and validation of updated firmware images are essential before deployment. Additionally, monitoring device logs for resource leak symptoms or abnormal device unbinding events can help detect potential issues early. Organizations should also review their device management procedures to minimize unnecessary unbinding of MMC devices and consider implementing watchdog mechanisms to recover from device failures. Maintaining an inventory of devices using the affected driver and their kernel versions will aid in prioritizing remediation efforts.