CVE-2025-38404: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability in the Linux kernel's USB Type-C DisplayPort functionality was identified and tracked as CVE-2025-38404. The issue was discovered and reported on July 24, 2025, affecting the USB subsystem's handling of DisplayPort alternate mode operations (Red Hat Portal).

The vulnerability stems from a potential deadlock condition in the USB Type-C DisplayPort subsystem. The deadlock occurs due to a recursive lock acquisition of cros_typec_altmode_data::mutex. The call chain involves crostypecaltmodework() acquiring the mutex, followed by typecaltmodevdm() -> dpaltmodevdm() -> typecaltmodeexit() -> crostypecaltmodeexit(), where the latter attempts to acquire the mutex again. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 with vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (Red Hat Portal).

The vulnerability can result in a system deadlock when specific USB Type-C DisplayPort operations are performed. This could lead to temporary system unavailability, affecting the normal operation of USB DisplayPort functionality (Red Hat Portal).

The issue has been resolved by deferring the typec_altmode_exit() call through scheduling rather than calling it directly from within the mutex-protected context. This prevents the recursive mutex acquisition that leads to the deadlock (Red Hat Portal).