CVE-2025-38105: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-38105 is a vulnerability discovered in the Linux kernel affecting the USB-audio MIDI code. The vulnerability was disclosed on July 3, 2025, and involves a timer initialization issue in the ALSA USB-audio subsystem (NVD, CVE).

The vulnerability occurs when the USB-audio MIDI code initializes a timer, but in rare cases, the driver might be freed without the disconnect call. This leaves the timer in an active state while the assigned object is released via snd_usbmidi_free(), resulting in a kernel warning when debug configuration is enabled. The issue was initially spotted by a fuzzer (NVD).

The vulnerability affects multiple Ubuntu releases including 25.04 plucky, 24.04 LTS noble, and 22.04 LTS jammy, as well as various kernel packages such as linux-aws, linux-azure, and linux-gcp. The issue primarily impacts systems with USB-audio MIDI devices (Ubuntu).

The fix involves implementing timer_shutdown_sync() at snd_usbmidi_free() to ensure proper timer cleanup. Additionally, the existing timer_delete_sync() at the disconnect callback has been replaced with timer_shutdown_sync() for consistency (NVD).