static ssize_t ucma_query_path(struct ucma_context *ctx,
			       void __user *response, int out_len)
{
	struct rdma_ucm_query_path_resp *resp;
	int i, ret = 0;

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

	resp = kzalloc(out_len, GFP_KERNEL);
	if (!resp)
		return -ENOMEM;

	resp->num_paths = ctx->cm_id->route.num_paths;
	for (i = 0, out_len -= sizeof(*resp);
	     i < resp->num_paths && out_len > sizeof(struct ib_path_rec_data);
	     i++, out_len -= sizeof(struct ib_path_rec_data)) {
		struct sa_path_rec *rec = &ctx->cm_id->route.path_rec[i];

		resp->path_data[i].flags = IB_PATH_GMP | IB_PATH_PRIMARY |
					   IB_PATH_BIDIRECTIONAL;
		if (rec->rec_type == SA_PATH_REC_TYPE_OPA) {
			struct sa_path_rec ib;

			sa_convert_path_opa_to_ib(&ib, rec);
			ib_sa_pack_path(&ib, &resp->path_data[i].path_rec);

		} else {
			ib_sa_pack_path(rec, &resp->path_data[i].path_rec);
		}
	}

	if (copy_to_user(response, resp,
			 sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))))
		ret = -EFAULT;

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.