struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
{
	struct kern_ipc_perm *out;
	int lid = ipcid_to_idx(id);

	out = idr_find(&ids->ipcs_idr, lid);
	if (!out)
		return ERR_PTR(-EINVAL);

	return out;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.