[PATCH 5.10 008/452] ALSA: usb-audio: Cancel pending work at closing a MIDI substream

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit 0125de38122f0f66bf61336158d12a1aabfe6425 upstream.

At closing a USB MIDI output substream, there might be still a pending
work, which would eventually access the rawmidi runtime object that is
being released.  For fixing the race, make sure to cancel the pending
work at closing.

Reported-by: syzbot+6912c9592caca7ca0e7d@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/000000000000e7e75005dfd07cf6@xxxxxxxxxx
Link: https://lore.kernel.org/r/20220525131203.11299-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 sound/usb/midi.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1161,6 +1161,9 @@ static int snd_usbmidi_output_open(struc
 
 static int snd_usbmidi_output_close(struct snd_rawmidi_substream *substream)
 {
+	struct usbmidi_out_port *port = substream->runtime->private_data;
+
+	cancel_work_sync(&port->ep->work);
 	return substream_open(substream, 0, 0);
 }