[alsa-devel] [patch] oss/sb_audio: prevent divide by zero bug

18 Aug 2012

Speed comes from get_user() in audio_ioctl().  We use it to set the "s"
variable before clamping it to valid values so it could lead to a divide
by zero bug.
Signed-off-by: Dan Carpenter dan.carpenter@oracle.com

diff --git a/sound/oss/sb_audio.c b/sound/oss/sb_audio.c
index 733b014..b2b3c01 100644
--- a/sound/oss/sb_audio.c
+++ b/sound/oss/sb_audio.c
@@ -575,13 +575,15 @@ static int jazz16_audio_set_speed(int dev, int speed)
    if (speed > 0)
    {
    	int tmp;
-		int s = speed * devc->channels;
+		int s;
if (speed < 5000)
    		speed = 5000;
    	if (speed > 44100)
    		speed = 44100;
+		s = speed * devc->channels;
+
    	devc->tconst = (256 - ((1000000 + s / 2) / s)) & 0xff;
tmp = 256 - devc->tconst;

    