ALSA: emux: Avoid potential array out-of-bound in snd_emux_xg_control()

snd_emux_xg_control() can be called with an argument 'param' greater
than size of 'control' array. It may lead to accessing 'control'
array at a wrong index.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Artemii Karasev <[e-mail]>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/synth/emux/emux_nrpn.c

···
 snd_emux_xg_control(struct snd_emux_port *port, struct snd_midi_channel *chan,
 		    int param)
 {
+	if (param >= ARRAY_SIZE(chan->control))
+		return -EINVAL;
+
 	return send_converted_effect(xg_effects, ARRAY_SIZE(xg_effects),
 				     port, chan, param,
 				     chan->control[param],