ALSA: usb-audio: Bound MIDI 2.0 endpoint descriptor scans

In the Linux kernel, the following vulnerability has been resolved:

ALSA: usb-audio: Bound MIDI 2.0 endpoint descriptor scans

The USB MIDI 2.0 endpoint parser has the same descriptor walking pattern as the legacy MIDI parser. It validates bLength against bNumGrpTrmBlock before reading baAssoGrpTrmBlkID[], but not against the remaining bytes in the endpoint-extra scan.

A malformed device can therefore make later baAssoGrpTrmBlkID[] reads consume bytes past the walked descriptor.

Reject zero-length and overlong descriptors while walking endpoint extras.