ALSA: hda/realtek - Fix Oops in alc_mux_select()

commit cce4aa378a049f4275416ee6302dd24f37b289df upstream.

When no imux is available (e.g. a single capture source),
alc_auto_init_input_src() may trigger an Oops due to the access to -1.
Add a proper zero-check to avoid it.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
[PG: in mainline, 21268961d3 rewrites and creates alc_mux_select, but the
code that needed the check still existed prior to that in alc_mux_enum_put]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
index 94f1a80b3cd954cfea1e908d7300925d6930c70a..28118fd195a22fb32ffe42a9096bb7af372d368d 100644 (file)
--- a/sound/pci/hda/patch_realtek.c
+++ b/sound/pci/hda/patch_realtek.c
@@ -444,6 +444,8 @@ static int alc_mux_enum_put(struct snd_kcontrol *kcontrol,
        imux = &spec->input_mux[mux_idx];
        if (!imux->num_items && mux_idx > 0)
                imux = &spec->input_mux[0];
+       if (!imux->num_items)
+               return 0;
 
        type = get_wcaps_type(get_wcaps(codec, nid));
        if (type == AC_WID_AUD_MIX) {