can-bcm: fix minor heap overflow

On 64-bit platforms the ASCII representation of a pointer may be up to 17
bytes long. This patch increases the length of the buffer accordingly.

http://marc.info/?l=linux-netdev&m=128872251418192&w=2

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
CC: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/can/bcm.c

@@ -125,7 +125,7 @@ struct bcm_sock {
 	struct list_head tx_ops;
 	unsigned long dropped_usr_msgs;
 	struct proc_dir_entry *bcm_proc_read;
-	char procname [9]; /* pointer printed in ASCII with \0 */
+	char procname [20]; /* pointer printed in ASCII with \0 */
 };
 
 static inline struct bcm_sock *bcm_sk(const struct sock *sk)