static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	struct ion_client *client = filp->private_data;
	struct ion_device *dev = client->dev;
	struct ion_handle *cleanup_handle = NULL;
	int ret = 0;
	unsigned int dir;

	union {
		struct ion_fd_data fd;
		struct ion_allocation_data allocation;
		struct ion_handle_data handle;
		struct ion_custom_data custom;
	} data;

	dir = ion_ioctl_dir(cmd);

	if (_IOC_SIZE(cmd) > sizeof(data))
		return -EINVAL;

	if (dir & _IOC_WRITE)
		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
			return -EFAULT;

	switch (cmd) {
	case ION_IOC_ALLOC:
	{
		struct ion_handle *handle;

		handle = ion_alloc(client, data.allocation.len,
						data.allocation.align,
						data.allocation.heap_id_mask,
						data.allocation.flags);
		if (IS_ERR(handle))
			return PTR_ERR(handle);

		data.allocation.handle = handle->id;

		cleanup_handle = handle;
		break;
	}
	case ION_IOC_FREE:
 	{
 		struct ion_handle *handle;
 
		handle = ion_handle_get_by_id(client, data.handle.handle);
		if (IS_ERR(handle))
 			return PTR_ERR(handle);
		ion_free(client, handle);
		ion_handle_put(handle);
 		break;
 	}
 	case ION_IOC_SHARE:
	case ION_IOC_MAP:
	{
		struct ion_handle *handle;

		handle = ion_handle_get_by_id(client, data.handle.handle);
		if (IS_ERR(handle))
			return PTR_ERR(handle);
		data.fd.fd = ion_share_dma_buf_fd(client, handle);
		ion_handle_put(handle);
		if (data.fd.fd < 0)
			ret = data.fd.fd;
		break;
	}
	case ION_IOC_IMPORT:
	{
		struct ion_handle *handle;

		handle = ion_import_dma_buf_fd(client, data.fd.fd);
		if (IS_ERR(handle))
			ret = PTR_ERR(handle);
		else
			data.handle.handle = handle->id;
		break;
	}
	case ION_IOC_SYNC:
	{
		ret = ion_sync_for_device(client, data.fd.fd);
		break;
	}
	case ION_IOC_CUSTOM:
	{
		if (!dev->custom_ioctl)
			return -ENOTTY;
		ret = dev->custom_ioctl(client, data.custom.cmd,
						data.custom.arg);
		break;
	}
	default:
		return -ENOTTY;
	}

	if (dir & _IOC_READ) {
		if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd))) {
			if (cleanup_handle)
				ion_free(client, cleanup_handle);
			return -EFAULT;
		}
	}
	return ret;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.