1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/isdn/capi/capidrv.c b/drivers/isdn/capi/capidrv.c
index 2978bdaa6b8..e54e79d4e2c 100644
--- a/drivers/isdn/capi/capidrv.c
+++ b/drivers/isdn/capi/capidrv.c
@@ -1515,8 +1515,13 @@ static int decodeFVteln(char *teln, unsigned long *bmaskp, int *activep)
         while (*s) {
                 int digit1 = 0;
                 int digit2 = 0;
-                if (!isdigit(*s)) return -3;
-                while (isdigit(*s)) { digit1 = digit1*10 + (*s - '0'); s++; }
+                char *endp;
+
+                digit1 = simple_strtoul(s, &endp, 10);
+                if (s == endp)
+                        return -3;
+                s = endp;
+
                 if (digit1 <= 0 || digit1 > 30) return -4;
                 if (*s == 0 || *s == ',' || *s == ' ') {
                         bmask |= (1 << digit1);
@@ -1526,8 +1531,12 @@ static int decodeFVteln(char *teln, unsigned long *bmaskp, int *activep)
                 }
                 if (*s != '-') return -5;
                 s++;
-                if (!isdigit(*s)) return -3;
-                while (isdigit(*s)) { digit2 = digit2*10 + (*s - '0'); s++; }
+
+                digit2 = simple_strtoul(s, &endp, 10);
+                if (s == endp)
+                        return -3;
+                s = endp;
+
                 if (digit2 <= 0 || digit2 > 30) return -4;
                 if (*s == 0 || *s == ',' || *s == ' ') {
                         if (digit1 > digit2)