isdn: icn: buffer overflow in icn_command()

This buffer over was detected using static analysis:

	drivers/isdn/icn/icn.c:1325 icn_command()
	error: format string overflow. buf_size: 60 length: 98

The calculation for the length of the string is off because it assumes
that the dial[] buffer holds a 50 character string, but actually it is
at most 31 characters and NUL.  I have removed the dial[] buffer because
it isn't needed.

The maximum length of the string is actually 79 characters and a NUL.  I
have made the cbuf[] array large enough to hold it and changed the
sprintf() to an snprintf() as a further safety enhancement.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/isdn/icn/icn.c b/drivers/isdn/icn/icn.c
index 53d487f0c79d..6a7447c304ac 100644
--- a/drivers/isdn/icn/icn.c
+++ b/drivers/isdn/icn/icn.c
@@ -1155,7 +1155,7 @@ icn_command(isdn_ctrl *c, icn_card *card)
         ulong a;
         ulong flags;
         int i;
-        char cbuf[60];
+        char cbuf[80];
         isdn_ctrl cmd;
         icn_cdef cdef;
         char __user *arg;
@@ -1309,7 +1309,6 @@ icn_command(isdn_ctrl *c, icn_card *card)
                         break;
                 if ((c->arg & 255) < ICN_BCH) {
                         char *p;
-                        char dial[50];
                         char dcode[4];
 
                         a = c->arg;
@@ -1321,10 +1320,10 @@ icn_command(isdn_ctrl *c, icn_card *card)
                         } else
                                 /* Normal Dial */
                                 strcpy(dcode, "CAL");
-                        strcpy(dial, p);
-                        sprintf(cbuf, "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
-                                dcode, dial, c->parm.setup.si1,
-                                c->parm.setup.si2, c->parm.setup.eazmsn);
+                        snprintf(cbuf, sizeof(cbuf),
+                                 "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
+                                 dcode, p, c->parm.setup.si1,
+                                 c->parm.setup.si2, c->parm.setup.eazmsn);
                         i = icn_writecmd(cbuf, strlen(cbuf), 0, card);
                 }
                 break;