CVE-2024-42090 is a vulnerability identified in the Linux kernel's pinctrl subsystem, specifically within the create_pinctrl() function. The issue arises due to improper mutex handling that can lead to a deadlock condition. In detail, create_pinctrl() acquires the pinctrl_maps_mutex before invoking add_setting(). If add_setting() returns the error code -EPROBE_DEFER, which signals that a device driver probe should be deferred, create_pinctrl() subsequently calls pinctrl_free() to clean up. However, pinctrl_free() also attempts to acquire the same pinctrl_maps_mutex that is already held by create_pinctrl(), resulting in a deadlock scenario where the mutex cannot be acquired again, and the kernel thread is blocked indefinitely. This deadlock can halt the progress of kernel initialization or device probing processes that rely on pinctrl, potentially causing system instability or hangs. The vulnerability was discovered and fixed through static analysis using Coverity SAST by Synopsys, which identified the mutex acquisition order flaw. The patch resolves the issue by ensuring that pinctrl_maps_mutex is released before calling pinctrl_free(), thereby preventing the deadlock. The vulnerability affects multiple versions of the Linux kernel as indicated by the repeated commit hashes, and no known exploits have been reported in the wild as of the publication date (July 29, 2024). No CVSS score has been assigned yet, and the vulnerability does not require user interaction or authentication but involves kernel-level code execution paths during device initialization.

For European organizations, the impact of CVE-2024-42090 primarily concerns system stability and availability. Since the vulnerability can cause deadlocks in the Linux kernel's pinctrl subsystem, affected systems may experience hangs or freezes during device initialization or driver probing phases. This can lead to denial of service conditions, especially in environments where Linux is used in embedded systems, industrial control, telecommunications infrastructure, or data centers. Organizations relying on Linux-based servers, IoT devices, or network equipment that utilize the affected kernel versions may face operational disruptions. Although the vulnerability does not directly expose confidentiality or integrity risks, the resulting system unavailability could impact critical services, leading to downtime and potential financial losses. The absence of known exploits reduces immediate risk, but the vulnerability's presence in widely deployed Linux kernels means that timely patching is essential to maintain system reliability. European sectors such as manufacturing, energy, and telecommunications, which often use Linux in embedded or specialized hardware, may be particularly sensitive to this issue.

To mitigate CVE-2024-42090, European organizations should prioritize updating their Linux kernel to the patched version that includes the fix for the pinctrl deadlock. This involves: 1) Identifying all systems running affected Linux kernel versions, especially those involved in device initialization or embedded use cases. 2) Applying vendor-supplied kernel updates or patches that address this specific deadlock issue. 3) For custom or in-house kernel builds, integrating the patch that releases pinctrl_maps_mutex before calling pinctrl_free(). 4) Testing updated kernels in staging environments to ensure stability and compatibility before production deployment. 5) Monitoring system logs for signs of deadlocks or hangs related to pinctrl or device probing to detect potential exploitation or manifestation of the vulnerability. 6) Implementing robust system monitoring and automated recovery mechanisms to minimize downtime if a deadlock occurs. 7) Engaging with hardware and software vendors to confirm that their Linux-based products have incorporated the fix. These steps go beyond generic advice by focusing on kernel-level patch management, targeted monitoring, and vendor coordination specific to this deadlock vulnerability.