From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 23 Mar 2015 09:41:31 +0000
Subject: [patch] ALSA: echoaudio: read past end of array
Message-Id: <20150323094131.GE558@mwanda>
List-Id: <kernel-janitors.vger.kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>, alsa-devel@alsa-project.org, kernel-janitors@vger.kernel.org, Sudip Mukherjee <sudipm.mukherjee@gmail.com>, Sachin Kamat <sachin.kamat@samsung.com>

We need to cap "ucontrol->id.index / num_busses_in(chip)" so the we
don't read beyond the end of the array.

I also adding a check on "in" and changing the type in
snd_echo_mixer_put() from short to unsigned int. Those changes are done
for symmetry and are cosmetic.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
index a962de0..862db9a 100644
--- a/sound/pci/echoaudio/echoaudio.c
+++ b/sound/pci/echoaudio/echoaudio.c
@@ -1283,12 +1283,14 @@ static int snd_echo_mixer_info(struct snd_kcontrol *kcontrol,
 static int snd_echo_mixer_get(struct snd_kcontrol *kcontrol,
 			      struct snd_ctl_elem_value *ucontrol)
 {
-	struct echoaudio *chip;
+	struct echoaudio *chip = snd_kcontrol_chip(kcontrol);
+	unsigned int out = ucontrol->id.index / num_busses_in(chip);
+	unsigned int in = ucontrol->id.index % num_busses_in(chip);
 
-	chip = snd_kcontrol_chip(kcontrol);
-	ucontrol->value.integer.value[0] -		chip->monitor_gain[ucontrol->id.index / num_busses_in(chip)]
-			[ucontrol->id.index % num_busses_in(chip)];
+	if (out >= ECHO_MAXAUDIOOUTPUTS || in >= ECHO_MAXAUDIOINPUTS)
+		return -EINVAL;
+
+	ucontrol->value.integer.value[0] = chip->monitor_gain[out][in];
 	return 0;
 }
 
@@ -1297,12 +1299,14 @@ static int snd_echo_mixer_put(struct snd_kcontrol *kcontrol,
 {
 	struct echoaudio *chip;
 	int changed,  gain;
-	short out, in;
+	unsigned int out, in;
 
 	changed = 0;
 	chip = snd_kcontrol_chip(kcontrol);
 	out = ucontrol->id.index / num_busses_in(chip);
 	in = ucontrol->id.index % num_busses_in(chip);
+	if (out >= ECHO_MAXAUDIOOUTPUTS || in >= ECHO_MAXAUDIOINPUTS)
+		return -EINVAL;
 	gain = ucontrol->value.integer.value[0];
 	if (gain < ECHOGAIN_MINOUT || gain > ECHOGAIN_MAXOUT)
 		return -EINVAL;