Bluetooth: bnep: fix buffer overflow

commit 43629f8f upstream.

Struct ca is copied from userspace.  It is not checked whether the "device"
field is NULL terminated.  This potentially leads to BUG() inside of
alloc_netdev_mqs() and/or information leak by creating a device with a name
made of contents of kernel stack.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/bluetooth/bnep/sock.c

@@ -88,6 +88,7 @@ static int bnep_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long
 			sockfd_put(nsock);
 			return -EBADFD;
 		}
+		ca.device[sizeof(ca.device)-1] = 0;
 
 		err = bnep_add_connection(&ca, nsock);
 		if (!err) {