static struct kioctx *lookup_ioctx(unsigned long ctx_id)
{
	struct mm_struct *mm = current->mm;
	struct kioctx *ctx, *ret = NULL;
	struct hlist_node *n;

	rcu_read_lock();

	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
		/*
		 * RCU protects us against accessing freed memory but
		 * we have to be careful not to get a reference when the
		 * reference count already dropped to 0 (ctx->dead test
		 * is unreliable because of races).
		 */
		if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
			ret = ctx;
			break;
		}
	}

	rcu_read_unlock();
	return ret;
}

This vulnerability category highlights issues in resource management where failures to properly release memory, file handles, or other resources can degrade system performance or enable denial-of-service conditions.