CVE-2026-74387 ALSA: seq: midi: Serialize output teardown with event_input

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: midi: Serialize output teardown with eventinput eventprocessmidi borrows msynth-outputrfile.output and then passes the substream to dumpmidi and sndrawmidikernelwrite without synchronizing with the output open/close...