If the sequencer device outlives the rawmidi device, then
snd_rawmidi_dev_seq_free() will run after release_rawmidi_device() has
freed the snd_rawmidi structure.
This can easily be reproduced with CONFIG_DEBUG_KOBJECT_RELEASE.
Keep a reference to the rawmidi device until the sequencer has been
destroyed in order to avoid this.
Signed-off-by: John Keeping <john@xxxxxxxxxxxx>
---
sound/core/rawmidi.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index 6f30231bdb88..b015f5f69175 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -1860,6 +1860,7 @@ static void snd_rawmidi_dev_seq_free(struct snd_seq_device *device)
struct snd_rawmidi *rmidi = device->private_data;
rmidi->seq_dev = NULL;
+ put_device(&rmidi->dev);
}
#endif
@@ -1936,6 +1937,9 @@ static int snd_rawmidi_dev_register(struct snd_device *device)
#if IS_ENABLED(CONFIG_SND_SEQUENCER)
if (!rmidi->ops || !rmidi->ops->dev_register) { /* own registration mechanism */
if (snd_seq_device_new(rmidi->card, rmidi->device, SNDRV_SEQ_DEV_ID_MIDISYNTH, 0, &rmidi->seq_dev) >= 0) {
+ /* Ensure we outlive the sequencer (see snd_rawmidi_dev_seq_free). */
+ get_device(&rmidi->dev);
+
rmidi->seq_dev->private_data = rmidi;
rmidi->seq_dev->private_free = snd_rawmidi_dev_seq_free;
sprintf(rmidi->seq_dev->name, "MIDI %d-%d", rmidi->card->number, rmidi->device);
--
2.33.0
