static ssize_t ucma_init_qp_attr(struct ucma_file *file,
				 const char __user *inbuf,
				 int in_len, int out_len)
{
	struct rdma_ucm_init_qp_attr cmd;
	struct ib_uverbs_qp_attr resp;
	struct ucma_context *ctx;
	struct ib_qp_attr qp_attr;
	int ret;

	if (out_len < sizeof(resp))
		return -ENOSPC;

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

	if (cmd.qp_state > IB_QPS_ERR)
		return -EINVAL;

	ctx = ucma_get_ctx_dev(file, cmd.id);
	if (IS_ERR(ctx))
		return PTR_ERR(ctx);

	resp.qp_attr_mask = 0;
	memset(&qp_attr, 0, sizeof qp_attr);
	qp_attr.qp_state = cmd.qp_state;
	ret = rdma_init_qp_attr(ctx->cm_id, &qp_attr, &resp.qp_attr_mask);
	if (ret)
		goto out;

	ib_copy_qp_attr_to_user(ctx->cm_id->device, &resp, &qp_attr);
	if (copy_to_user(u64_to_user_ptr(cmd.response),
			 &resp, sizeof(resp)))
		ret = -EFAULT;

out:
	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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.