static ssize_t ucma_get_event(struct ucma_file *file, const char __user *inbuf,
			      int in_len, int out_len)
{
	struct ucma_context *ctx;
	struct rdma_ucm_get_event cmd;
	struct ucma_event *uevent;
	int ret = 0;

	/*
	 * Old 32 bit user space does not send the 4 byte padding in the
	 * reserved field. We don't care, allow it to keep working.
	 */
	if (out_len < sizeof(uevent->resp) - sizeof(uevent->resp.reserved))
		return -ENOSPC;

	if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
		return -EFAULT;

	mutex_lock(&file->mut);
	while (list_empty(&file->event_list)) {
		mutex_unlock(&file->mut);

		if (file->filp->f_flags & O_NONBLOCK)
			return -EAGAIN;

		if (wait_event_interruptible(file->poll_wait,
					     !list_empty(&file->event_list)))
			return -ERESTARTSYS;

		mutex_lock(&file->mut);
	}

	uevent = list_entry(file->event_list.next, struct ucma_event, list);

	if (uevent->resp.event == RDMA_CM_EVENT_CONNECT_REQUEST) {
		ctx = ucma_alloc_ctx(file);
		if (!ctx) {
			ret = -ENOMEM;
			goto done;
		}
		uevent->ctx->backlog++;
		ctx->cm_id = uevent->cm_id;
		ctx->cm_id->context = ctx;
		uevent->resp.id = ctx->id;
	}

	if (copy_to_user(u64_to_user_ptr(cmd.response),
			 &uevent->resp,
			 min_t(size_t, out_len, sizeof(uevent->resp)))) {
		ret = -EFAULT;
		goto done;
	}

	list_del(&uevent->list);
	uevent->ctx->events_reported++;
	if (uevent->mc)
		uevent->mc->events_reported++;
	kfree(uevent);
done:
	mutex_unlock(&file->mut);
	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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.