Executive brief
A Linux kernel audio driver for Focusrite Scarlett2 USB audio interfaces mismanages USB communication buffers, potentially leading to memory corruption or system crashes when the device is initialized or resumed from suspend. This affects users of these professional audio interfaces on Linux systems.
Technical details
The ALSA Scarlett2 driver incorrectly reused a shared URB (USB Request Block) managed by the USB mixer core for the notification endpoint. When a device had a UAC2 status interrupt endpoint, the shared URB would be flagged as "already in use," causing the driver to skip notification URB submission while leaving the completion semaphore uninitialized. This led to a null pointer dereference during wait_for_completion_timeout() in scarlett2_usb_init(). The fix allocates a private URB for scarlett2, initializes the completion semaphore in scarlett2_init_private(), and implements proper cleanup and resume callbacks to manage URB lifecycle. Additional fixes include proper error handling for failed buffer allocations and usb_submit_urb() failures, and use of reinit_completion() to prevent stale completion counts.
Affected products
- Linux Linux kernel <UNKNOWN>
Timeline
- 2026-09-04: patched