CVE-2025-21835

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

usb: gadget: f_midi: fix MIDI Streaming descriptor lengths

While the MIDI jacks are configured correctly, and the MIDIStreaming endpoint descriptors are filled with the correct information, bNumEmbMIDIJack and bLength are set incorrectly in these descriptors.

This does not matter when the numbers of in and out ports are equal, but when they differ the host will receive broken descriptors with uninitialized stack memory leaking into the descriptor for whichever value is smaller.

The precise meaning of "in" and "out" in the port counts is not clearly defined and can be confusing. But elsewhere the driver consistently uses this to match the USB meaning of IN and OUT viewed from the host, so that "in" ports send data to the host and "out" ports receive data from it.