ALSA: hda: generic: Check potential mixer name string truncation

add_control_with_pfx() constructs a mixer name element with the fixed
size, and it got compile warnings with -Wformat-truncation.

Although the size overflow is very unlikely, let's have a sanity check
of the string size and returns the error if it really doesn't fit
instead of silent truncation.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: tiwai

sound/pci/hda/hda_generic.c

@@ -998,7 +998,11 @@ static int add_control_with_pfx(struct hda_gen_spec *spec, int type,
 				const char *sfx, int cidx, unsigned long val)
 {
 	char name[SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
-	snprintf(name, sizeof(name), "%s %s %s", pfx, dir, sfx);
+	int len;
+
+	len = snprintf(name, sizeof(name), "%s %s %s", pfx, dir, sfx);
+	if (snd_BUG_ON(len >= sizeof(name)))
+		return -EINVAL;
 	if (!add_control(spec, type, name, cidx, val))
 		return -ENOMEM;
 	return 0;