sanitize do_i2c_smbus_ioctl()

		unsigned int cmd, struct i2c_smbus_ioctl_data32   __user *udata)

{

	struct i2c_smbus_ioctl_data	__user *tdata;

	compat_caddr_t			datap;

	union {

		/* beginnings of those have identical layouts */

		struct i2c_smbus_ioctl_data32	data32;

		struct i2c_smbus_ioctl_data	data;

	} v;

	tdata = compat_alloc_user_space(sizeof(*tdata));

	if (tdata == NULL)

		return -ENOMEM;

	if (!access_ok(VERIFY_WRITE, tdata, sizeof(*tdata)))

		return -EFAULT;

	if (!access_ok(VERIFY_READ, udata, sizeof(*udata)))

	memset(&v, 0, sizeof(v));

	if (copy_from_user(&v.data32, udata, sizeof(v.data32)))

		return -EFAULT;

	v.data.data = compat_ptr(v.data32.data);

	if (__copy_in_user(&tdata->read_write, &udata->read_write, 2 * sizeof(u8)))

		return -EFAULT;

	if (__copy_in_user(&tdata->size, &udata->size, 2 * sizeof(u32)))

		return -EFAULT;

	if (__get_user(datap, &udata->data) ||

	    __put_user(compat_ptr(datap), &tdata->data))

	if (copy_to_user(tdata, &v.data, sizeof(v.data)))

		return -EFAULT;

	return do_ioctl(file, cmd, (unsigned long)tdata);