int ssl3_send_cert_status(SSL *s)
{
    if (s->state == SSL3_ST_SW_CERT_STATUS_A) {
        unsigned char *p;
        /*-
         * Grow buffer if need be: the length calculation is as
         * follows 1 (message type) + 3 (message length) +
         * 1 (ocsp response type) + 3 (ocsp response length)
         * + (ocsp response)
         */
        if (!BUF_MEM_grow(s->init_buf, 8 + s->tlsext_ocsp_resplen)) {
            s->state = SSL_ST_ERR;
            return -1;
        }

        p = (unsigned char *)s->init_buf->data;

        /* do the header */
        *(p++) = SSL3_MT_CERTIFICATE_STATUS;
        /* message length */
        l2n3(s->tlsext_ocsp_resplen + 4, p);
        /* status type */
        *(p++) = s->tlsext_status_type;
        /* length of OCSP response */
        l2n3(s->tlsext_ocsp_resplen, p);
        /* actual response */
        memcpy(p, s->tlsext_ocsp_resp, s->tlsext_ocsp_resplen);
        /* number of bytes to write */
        s->init_num = 8 + s->tlsext_ocsp_resplen;
        s->state = SSL3_ST_SW_CERT_STATUS_B;
        s->init_off = 0;
    }

    /* SSL3_ST_SW_CERT_STATUS_B */
    return (ssl3_do_write(s, SSL3_RT_HANDSHAKE));
}

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.