ALSA: hda: Fix potential access overflow in beep helper

commit 0ad3f0b384d58f3bd1f4fb87d0af5b8f6866f41a upstream.

The beep control helper function blindly stores the values in two
stereo channels no matter whether the actual control is mono or
stereo.  This is practically harmless, but it annoys the recently
introduced sanity check, resulting in an error when the checker is
enabled.

This patch corrects the behavior to store only on the defined array
member.

Fixes: 0401e8548eac ("ALSA: hda - Move beep helper functions to hda_beep.c")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207139
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200407084402.25589-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/pci/hda/hda_beep.c b/sound/pci/hda/hda_beep.c
index 066b5b59c4d7cc50c7c50de2a2f4d20cc07cf166..0224011a240fb620e7387961a7bf5923fb2cc44e 100644 (file)
--- a/sound/pci/hda/hda_beep.c
+++ b/sound/pci/hda/hda_beep.c
@@ -297,8 +297,12 @@ int snd_hda_mixer_amp_switch_get_beep(struct snd_kcontrol *kcontrol,
 {
        struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
        struct hda_beep *beep = codec->beep;
+       int chs = get_amp_channels(kcontrol);
+
        if (beep && (!beep->enabled || !ctl_has_mute(kcontrol))) {
-               ucontrol->value.integer.value[0] =
+               if (chs & 1)
+                       ucontrol->value.integer.value[0] = beep->enabled;
+               if (chs & 2)
                        ucontrol->value.integer.value[1] = beep->enabled;
                return 0;
        }