int ssl3_get_new_session_ticket(SSL *s)
{
    int ok, al, ret = 0, ticklen;
    long n;
    const unsigned char *p;
    unsigned char *d;

    n = s->method->ssl_get_message(s,
                                   SSL3_ST_CR_SESSION_TICKET_A,
                                   SSL3_ST_CR_SESSION_TICKET_B,
                                   SSL3_MT_NEWSESSION_TICKET, 16384, &ok);

    if (!ok)
        return ((int)n);

    if (n < 6) {
        /* need at least ticket_lifetime_hint + ticket length */
        al = SSL_AD_DECODE_ERROR;
        SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, SSL_R_LENGTH_MISMATCH);
        goto f_err;
     }
 
     p = d = (unsigned char *)s->init_msg;
     n2l(p, s->session->tlsext_tick_lifetime_hint);
     n2s(p, ticklen);
     /* ticket_lifetime_hint + ticket_length + ticket */
    if (ticklen + 6 != n) {
        al = SSL_AD_DECODE_ERROR;
        SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, SSL_R_LENGTH_MISMATCH);
        goto f_err;
    }
    OPENSSL_free(s->session->tlsext_tick);
    s->session->tlsext_ticklen = 0;
    s->session->tlsext_tick = OPENSSL_malloc(ticklen);
    if (!s->session->tlsext_tick) {
        SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    memcpy(s->session->tlsext_tick, p, ticklen);
    s->session->tlsext_ticklen = ticklen;
    /*
     * There are two ways to detect a resumed ticket session. One is to set
     * an appropriate session ID and then the server must return a match in
     * ServerHello. This allows the normal client session ID matching to work
     * and we know much earlier that the ticket has been accepted. The
     * other way is to set zero length session ID when the ticket is
     * presented and rely on the handshake to determine session resumption.
     * We choose the former approach because this fits in with assumptions
     * elsewhere in OpenSSL. The session ID is set to the SHA256 (or SHA1 is
     * SHA256 is disabled) hash of the ticket.
     */
    EVP_Digest(p, ticklen,
               s->session->session_id, &s->session->session_id_length,
               EVP_sha256(), NULL);
    ret = 1;
    return (ret);
 f_err:
    ssl3_send_alert(s, SSL3_AL_FATAL, al);
 err:
    s->state = SSL_ST_ERR;
    return (-1);
}

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.