static ssize_t ucma_query(struct ucma_file *file,
			  const char __user *inbuf,
			  int in_len, int out_len)
{
	struct rdma_ucm_query cmd;
	struct ucma_context *ctx;
	void __user *response;
	int ret;

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

	response = u64_to_user_ptr(cmd.response);
	ctx = ucma_get_ctx(file, cmd.id);
	if (IS_ERR(ctx))
		return PTR_ERR(ctx);

	switch (cmd.option) {
	case RDMA_USER_CM_QUERY_ADDR:
		ret = ucma_query_addr(ctx, response, out_len);
		break;
	case RDMA_USER_CM_QUERY_PATH:
		ret = ucma_query_path(ctx, response, out_len);
		break;
	case RDMA_USER_CM_QUERY_GID:
		ret = ucma_query_gid(ctx, response, out_len);
		break;
	default:
		ret = -ENOSYS;
		break;
	}

	ucma_put_ctx(ctx);
	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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.