ALSA: usb-audio: avoid freeing umidi object twice

commit 07d86ca9 upstream.

The 'umidi' object will be free'd on the error path by snd_usbmidi_free()
when tearing down the rawmidi interface. So we shouldn't try to free it
in snd_usbmidi_create() after having registered the rawmidi interface.

Found by KASAN.
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[wt: file is sound/midi/usbmidi.c in 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>

sound/usb/usbmidi.c

@@ -1947,7 +1947,6 @@ int snd_usb_create_midi_interface(struct snd_usb_audio* chip,
 	else
 		err = snd_usbmidi_create_endpoints(umidi, endpoints);
 	if (err < 0) {
-		snd_usbmidi_free(umidi);
 		return err;
 	}