ALSA: Add a reference counter to card instance
For more strict protection for wild disconnections, a refcount is
introduced to the card instance, and let it up/down when an object is
referred via snd_lookup_*() in the open ops.
The free-after-last-close check is also changed to check this refcount
instead of the empty list, too.
Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ebf6e49..7d4f62a 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -379,8 +379,10 @@
if (rmidi == NULL)
return -ENODEV;
- if (!try_module_get(rmidi->card->module))
+ if (!try_module_get(rmidi->card->module)) {
+ snd_card_unref(rmidi->card);
return -ENXIO;
+ }
mutex_lock(&rmidi->open_mutex);
card = rmidi->card;
@@ -440,6 +442,7 @@
#endif
file->private_data = rawmidi_file;
mutex_unlock(&rmidi->open_mutex);
+ snd_card_unref(rmidi->card);
return 0;
__error:
@@ -447,6 +450,7 @@
__error_card:
mutex_unlock(&rmidi->open_mutex);
module_put(rmidi->card->module);
+ snd_card_unref(rmidi->card);
return err;
}