Welcome to an in-depth analysis of CVE-2024-42085, a cybersecurity issue that impacts the Linux kernel's USB driver subsystem. Our aim is to provide clarity on what this issue means, how it affects your systems, and explain the technical measures taken to resolve it. Whether you are an IT professional, a developer, or just someone keen on understanding cyber vulnerabilities, you'll find this information critical.
CVE-2024-42085 is a deadlock vulnerability discovered within the DesignWare Core SuperSpeed (DWC3) USB 3.0 gadget driver in the Linux kernel. This particular issue was flagged with a 'MEDIUM' severity rating and a CVSS (Common Vulnerability Scoring System) score of 5.5. The vulnerability pertains to the improper handling of locks during the suspend/resume process of the USB gadget, specifically when the system configuration allows the USB DWC3 driver to operate in a dual-role mode.
The primary issue involves a certain operational condition where, upon executing a system suspension, the driver attempts to secure a lock that has been previously secured, resulting in a deadlock. This essentially freezes the impacted processes of the kernel, leading to potential denial of service conditions from the affected subsystem. Here’s a simplified view of the deadlock:
dwc3_suspend_common()
spin_lock_irqsave(&dwc->lock, flags); <-- 1st
dwc3_gadget_suspend(dwc);
dwc3_gadget_soft_disconnect(dwc);
spin_lock_irqsave(&dwc->lock, flags); <-- 2ndThe deadlock occurs because the lock acquired in the dwc3_suspend_common function is not released before re-attempting to acquire the same lock inside the dwc3_gadget_suspend function. This issue was inadvertently introduced in a recent code update aimed at correcting a different bug, which led to this unfortunate complication.
Upon identification of the problem, quick steps were taken to correct the deadlock issue. This was primarily achieved by removing the redundant locking mechanism during the USB gadget suspend/resume phases. This correction not only resolves the deadlock condition but also ensures that similar lock acquisition errors are avoided in the future within the same subsystem.
Linux users who potentially might be running affected versions of the kernel are strongly advised to update to the latest kernel version where this patch has been applied. Keeping your system updated is one of the simplest yet most effective ways to protect against vulnerabilities like CVE-2024-42085.
CVE-2024-42085 serves as a reminder of the intricacies involved in software and hardware integration, particularly in complex systems like the Linux kernel. While the severity rating is moderate, prompt attention and resolution are crucial to prevent potential disruptions. As always, adhering to proactive patch management and system updates is recommended to maintain security and functionality of your systems.
Stay secure and make sure to check back with us for more updates on cybersecurity and how to keep your systems safe!