bridge: netfilter: fix information leak

Struct tmp is copied from userspace.  It is not checked whether the "name"
field is NULL terminated.  This may lead to buffer overflow and passing
contents of kernel stack as a module name to try_then_request_module() and,
consequently, to modprobe commandline.  It would be seen by all userspace
processes.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
    const char *base, char __user *ubase)
{
	char __user *hlp = ubase + ((char *)w - base);
	if (copy_to_user(hlp , w->u.watcher->name, EBT_FUNCTION_MAXNAMELEN))
		return -EFAULT;
	return 0;
}

static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
    const char *base, char __user *ubase)
{
	char __user *hlp = ubase + ((char *)w - base);
	if (copy_to_user(hlp , w->u.watcher->name, EBT_FUNCTION_MAXNAMELEN))
		return -EFAULT;
	return 0;
}
