ALSA: usb-audio: Add check return value for usb_string()

commit 89b89d121ffcf8d9546633b98ded9d18b8f75891 upstream.

snd_usb_copy_string_desc() returns zero if usb_string() fails.
In case of failure, we need to check the snd_usb_copy_string_desc()'s
return value and add an exception case

Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 4e10164..883c54c 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1928,12 +1928,14 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid, void
        if (len)
                ;
        else if (nameid)
        if (len)
                ;
        else if (nameid)

-               snd_usb_copy_string_desc(state, nameid, kctl->id.name, sizeof(kctl->id.name));
-       else {
+               len = snd_usb_copy_string_desc(state, nameid, kctl->id.name,
+                                        sizeof(kctl->id.name));
+       else

                len = get_term_name(state, &state->oterm,
                                    kctl->id.name, sizeof(kctl->id.name), 0);
                len = get_term_name(state, &state->oterm,
                                    kctl->id.name, sizeof(kctl->id.name), 0);

-               if (! len)
-                       strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
+
+       if (!len) {
+               strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));

 
                if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
                        append_ctl_name(kctl, " Clock Source");
 
                if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
                        append_ctl_name(kctl, " Clock Source");