CVE-2024-42085 is a vulnerability in the Linux kernel's USB subsystem, specifically within the DesignWare Core USB3 (dwc3) driver when configured with CONFIG_USB_DWC3_DUAL_ROLE. The issue arises during system suspend/resume operations triggered by echoing 'mem' to /sys/power/state, which causes the system to enter suspend mode. The vulnerability is a deadlock condition caused by improper locking behavior in the dwc3 driver. The root cause stems from a previous commit (5265397f9442) that removed locking during gadget suspend/resume but failed to remove the lock related to OTG (On-The-Go) mode. This results in nested spinlock acquisitions on the same lock (dwc->lock) within the suspend path: dwc3_suspend_common() acquires the lock first, then dwc3_gadget_suspend() calls dwc3_gadget_soft_disconnect(), which attempts to acquire the same lock again, causing a deadlock. The deadlock prevents the system from properly suspending or resuming USB gadget functionality, potentially freezing the system or causing USB device malfunction. This vulnerability was introduced by a commit that removed a NULL pointer check on dwc->gadget_driver, which exposed the deadlock scenario. The fix involves removing the redundant OTG mode lock during gadget suspend/resume to prevent the deadlock. This vulnerability affects Linux kernel versions containing the specified commits and configurations enabling dual-role USB functionality in the dwc3 driver. No known exploits are reported in the wild as of now.

For European organizations, this vulnerability primarily impacts systems running Linux kernels with the affected dwc3 USB driver configuration, especially embedded devices, IoT devices, or servers using USB dual-role functionality. The deadlock can cause system hangs or failures during suspend/resume cycles, leading to availability issues. This can disrupt critical operations in environments relying on USB devices for connectivity or data transfer, such as industrial control systems, telecommunications infrastructure, or enterprise servers. Organizations using Linux-based devices in mobile or power-saving modes may experience increased system instability or downtime. Although the vulnerability does not directly expose confidentiality or integrity risks, the availability impact can be significant, especially in environments requiring high uptime or remote management. The lack of known exploits reduces immediate risk, but the vulnerability could be leveraged in targeted attacks to cause denial of service or disrupt device operations.

To mitigate this vulnerability, European organizations should: 1) Apply the official Linux kernel patches that remove the redundant OTG mode lock during gadget suspend/resume as soon as they become available from trusted sources or Linux distributions. 2) Review and audit kernel configurations to identify systems using CONFIG_USB_DWC3_DUAL_ROLE and assess their exposure. 3) For embedded or IoT devices, coordinate with device vendors to ensure firmware/kernel updates include the fix. 4) Temporarily disable USB dual-role functionality if feasible to avoid triggering the deadlock during suspend/resume cycles. 5) Implement monitoring for system hangs or USB subsystem failures that could indicate deadlock conditions. 6) Test suspend/resume operations in controlled environments after patching to confirm resolution. 7) Maintain up-to-date backups and recovery procedures to minimize downtime impact in case of system hangs. These steps go beyond generic advice by focusing on configuration auditing, vendor coordination, and operational monitoring specific to the affected USB subsystem.