CVE-2024-57913 is a vulnerability in the Linux kernel's USB gadget subsystem, specifically within the FunctionFS (functionfs) driver. The issue arises from the use of WARN_ON in the functionfs_bind() function, which can trigger a kernel panic when the kernel parameter panic_on_warn is enabled. The root cause is a race condition between two paths: one involving adb_write operations invoked by the adbd daemon, and another involving UDC (USB Device Controller) writes via configfs. These two paths attempt to bind the USB function concurrently, leading to a state where WARN_ON triggers due to an unexpected functionfs state (ffs->state != FFS_ACTIVE). This results in a kernel panic with the message "kernel panic - not syncing: kernel: panic_on_warn set ..." and a call trace pointing to the functionfs_bind and related USB gadget driver functions. The vulnerability does not appear to allow direct code execution or privilege escalation but causes a denial of service (DoS) by crashing the kernel. The patch removes the unnecessary WARN_ON to prevent the panic, addressing the race condition. The affected versions are identified by a specific commit hash, indicating the issue is present in certain Linux kernel versions prior to the fix. No known exploits are reported in the wild as of the publication date.

For European organizations, this vulnerability primarily poses a risk of denial of service on Linux systems that utilize the USB gadget FunctionFS driver, particularly in environments where panic_on_warn is enabled (often in development, embedded, or specialized systems). Systems that rely on USB gadget functionality for device emulation, testing, or embedded USB device roles could experience unexpected kernel panics, leading to system crashes and potential downtime. This can disrupt critical services, especially in industrial control systems, telecommunications, or IoT deployments common in sectors like manufacturing, healthcare, and transportation across Europe. While the vulnerability does not directly expose data or allow remote code execution, the resulting instability could be exploited to cause operational disruptions. Organizations with Linux-based embedded devices or servers that handle USB gadget configurations should be particularly vigilant. The impact is more pronounced in environments where system availability is critical and where kernel panic recovery is not automated or rapid.

To mitigate this vulnerability, European organizations should: 1) Apply the official Linux kernel patches that remove the WARN_ON in functionfs_bind as soon as they are available and tested. 2) Review and update Linux kernel versions to those that include the fix for CVE-2024-57913. 3) Disable or avoid enabling panic_on_warn in production environments unless necessary, as this setting exacerbates the impact of this issue. 4) Monitor USB gadget usage and configurations, especially those involving FunctionFS and configfs, to detect unusual or concurrent binding attempts that could trigger the race condition. 5) Implement robust system monitoring and automated recovery mechanisms to handle unexpected kernel panics, minimizing downtime. 6) For embedded and IoT devices, coordinate with vendors to ensure firmware/kernel updates include this fix. 7) Conduct thorough testing of USB gadget functionality after patching to confirm stability and absence of regressions. These steps go beyond generic advice by focusing on configuration management, kernel version control, and operational readiness specific to the USB gadget subsystem.