In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Serialize UMP output teardown with event_input seq_ump_process_event() borrows client->out_rfile.output without synchr…

Summary

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Serialize UMP output teardown with event_input seq_ump_process_event() borrows client->out_rfile.output without synchronizing with the first-open and last-close transition in seq_ump_client_open() and seq_ump_client_close(). The last output unuse can therefore drop opened[STR_OUT] to zero and release the rawmidi file while an in-flight event_input callback is still inside snd_rawmidi_kernel_write(). That leaves th…