ALSA: line6: Fix memory leak at line6_init_pcm() error path

BugLink: https://bugs.launchpad.net/bugs/1860681

commit 1bc8d18c upstream.

I forgot to release the allocated object at the early error path in
line6_init_pcm().  For addressing it, slightly shuffle the code so
that the PCM destructor (pcm->private_free) is assigned properly
before all error paths.

Fixes: 34501219 ("ALSA: line6: Fix write on zero-sized buffer")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

sound/usb/line6/pcm.c

@@ -523,6 +523,15 @@ int line6_init_pcm(struct usb_line6 *line6,
 	line6pcm->volume_monitor = 255;
 	line6pcm->line6 = line6;
 
+	spin_lock_init(&line6pcm->out.lock);
+	spin_lock_init(&line6pcm->in.lock);
+	line6pcm->impulse_period = LINE6_IMPULSE_DEFAULT_PERIOD;
+
+	line6->line6pcm = line6pcm;
+
+	pcm->private_data = line6pcm;
+	pcm->private_free = line6_cleanup_pcm;
+
 	/* Read and write buffers are sized identically, so choose minimum */
 	line6pcm->max_packet_size = min(
 			usb_maxpacket(line6->usbdev,
@@ -535,15 +544,6 @@ int line6_init_pcm(struct usb_line6 *line6,
 		return -EINVAL;
 	}
 
-	spin_lock_init(&line6pcm->out.lock);
-	spin_lock_init(&line6pcm->in.lock);
-	line6pcm->impulse_period = LINE6_IMPULSE_DEFAULT_PERIOD;
-
-	line6->line6pcm = line6pcm;
-
-	pcm->private_data = line6pcm;
-	pcm->private_free = line6_cleanup_pcm;
-
 	err = line6_create_audio_out_urbs(line6pcm);
 	if (err < 0)
 		return err;