mISDN: Fix division by zero

If DTMF debug is set and tresh goes under 100, the printk will cause
a division by zero.

Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/isdn/mISDN/dsp_dtmf.c b/drivers/isdn/mISDN/dsp_dtmf.c
index 887860bdc63b..642f30be5ce2 100644
--- a/drivers/isdn/mISDN/dsp_dtmf.c
+++ b/drivers/isdn/mISDN/dsp_dtmf.c
@@ -222,16 +222,25 @@ coefficients:
                 goto storedigit;
         }
 
-        if (dsp_debug & DEBUG_DSP_DTMFCOEFF)
+        if (dsp_debug & DEBUG_DSP_DTMFCOEFF) {
+                s32 tresh_100 = tresh/100;
+
+                if (tresh_100 == 0) {
+                        tresh_100 = 1;
+                        printk(KERN_DEBUG
+                                "tresh(%d) too small set tresh/100 to 1\n",
+                                tresh);
+                }
                 printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d"
                        " tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n",
                        result[0] / 10000, result[1] / 10000, result[2] / 10000,
                        result[3] / 10000, result[4] / 10000, result[5] / 10000,
                        result[6] / 10000, result[7] / 10000, tresh / 10000,
-                       result[0] / (tresh / 100), result[1] / (tresh / 100),
-                       result[2] / (tresh / 100), result[3] / (tresh / 100),
-                       result[4] / (tresh / 100), result[5] / (tresh / 100),
-                       result[6] / (tresh / 100), result[7] / (tresh / 100));
+                       result[0] / (tresh_100), result[1] / (tresh_100),
+                       result[2] / (tresh_100), result[3] / (tresh_100),
+                       result[4] / (tresh_100), result[5] / (tresh_100),
+                       result[6] / (tresh_100), result[7] / (tresh_100));
+        }
 
         /* calc digit (lowgroup/highgroup) */
         lowgroup = -1;