static int check_trust(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
    return 1;
#else
    int i, ok;
    X509 *x;
    int (*cb) (int xok, X509_STORE_CTX *xctx);
    cb = ctx->verify_cb;
/* For now just check the last certificate in the chain */
    i = sk_X509_num(ctx->chain) - 1;
    x = sk_X509_value(ctx->chain, i);
    ok = X509_check_trust(x, ctx->param->trust, 0);
    if (ok == X509_TRUST_TRUSTED)
        return 1;
    ctx->error_depth = i;
    ctx->current_cert = x;
    if (ok == X509_TRUST_REJECTED)
        ctx->error = X509_V_ERR_CERT_REJECTED;
    else
        ctx->error = X509_V_ERR_CERT_UNTRUSTED;
    ok = cb(0, ctx);
    return ok;
#endif
}

This label identifies security gaps where expected security features are missing or only partially implemented, reducing protection against unauthorized access or manipulation.