ALSA: synth: missing check for possible NULL after the call to kstrdup

commit d159037abb upstream.

If kcalloc() return NULL due to memory starvation, it is possible for
kstrdup() to return NULL in similar case. So add null check after the call
to kstrdup() is made.

[ minor coding-style fix by tiwai ]

Signed-off-by: Austin Kim <austin.kim@lge.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211109003742.GA5423@raspberrypi
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sound/synth/emux/emux.c

@@ -88,7 +88,7 @@ int snd_emux_register(struct snd_emux *emu, struct snd_card *card, int index, ch
 	emu->name = kstrdup(name, GFP_KERNEL);
 	emu->voices = kcalloc(emu->max_voices, sizeof(struct snd_emux_voice),
 			      GFP_KERNEL);
-	if (emu->voices == NULL)
+	if (emu->name == NULL || emu->voices == NULL)
 		return -ENOMEM;
 
 	/* create soundfont list */