CVE-2024-50269 is a vulnerability identified in the Linux kernel specifically affecting the USB subsystem implementation for the musb (Mentor USB) controller on sunxi platforms. The root cause lies in improper handling of the USB PHY (physical layer) resource lifecycle. The vulnerability emerged due to a commit (6ed05c68cbca) that explicitly released the USB PHY resource during the driver exit routine (sunxi_musb_exit) by calling devm_usb_put_phy(). This release caused a use-after-free condition when the musb driver was re-registered and attempted to use the USB PHY that had already been released. The sequence of events is as follows: first, the platform driver sunxi_musb_driver registers and obtains the USB PHY resource via devm_usb_get_phy(). Then, the musb_driver registers and initializes the PHY for use. Upon removal, the musb_driver releases the PHY resource. However, when the musb_driver is registered again, it attempts to use the PHY which has already been released, leading to an invalid memory access. This use-after-free can cause kernel instability, crashes, or potentially allow attackers to execute arbitrary code or escalate privileges if exploited. The fix involved reverting the problematic commit and removing the call to devm_usb_put_phy() from the exit routine, ensuring the PHY resource is not prematurely released. This vulnerability affects specific Linux kernel versions containing the faulty commit and impacts systems using the musb USB controller on sunxi-based hardware platforms, which are common in embedded devices and some ARM-based systems.

For European organizations, the impact of CVE-2024-50269 depends largely on their deployment of Linux systems running on sunxi-based hardware with the musb USB controller. Such platforms are often found in embedded systems, IoT devices, industrial control systems, and specialized ARM-based servers or appliances. Exploitation of this vulnerability could lead to kernel crashes causing denial of service, or in worst cases, privilege escalation or arbitrary code execution within the kernel context. This could compromise the confidentiality, integrity, and availability of affected systems. Critical infrastructure operators, manufacturing, telecommunications, and enterprises using embedded Linux devices in Europe could face operational disruptions or security breaches. Given the kernel-level nature of the flaw, successful exploitation could allow attackers to bypass security controls, persist on devices, or pivot within networks. Although no known exploits are reported in the wild yet, the vulnerability’s presence in the Linux kernel source code means attackers with sufficient access or local privileges could develop exploits. The impact is particularly relevant for organizations relying on embedded Linux devices in sensitive environments or with regulatory compliance obligations under GDPR and NIS Directive.

1. Immediate patching: European organizations should update their Linux kernel to versions where the problematic commit has been reverted or patched. This involves applying the latest stable kernel releases or vendor-specific patches that address CVE-2024-50269. 2. Inventory and assessment: Identify all systems running Linux kernels with the affected musb driver on sunxi platforms, including embedded devices, IoT, and ARM-based servers. 3. Restrict access: Limit local user access to affected systems to reduce the risk of local exploitation, as this vulnerability requires local code execution or privileged access to trigger. 4. Monitor logs and behavior: Implement enhanced monitoring for kernel crashes, USB subsystem errors, or unusual device behavior that could indicate exploitation attempts. 5. Vendor coordination: Work with hardware and Linux distribution vendors to obtain timely patches and guidance for embedded devices that may not receive regular updates. 6. Network segmentation: Isolate vulnerable embedded devices from critical network segments to contain potential compromise. 7. Disable unused USB ports or controllers on affected devices where feasible to reduce attack surface. 8. For custom or in-house Linux builds, review kernel configuration and driver usage to avoid loading the vulnerable musb driver if not required.