ProcEstablishConnection(ClientPtr client)
{
    const char *reason;
    char *auth_proto, *auth_string;
    xConnClientPrefix *prefix;

    REQUEST(xReq);

    prefix = (xConnClientPrefix *) ((char *) stuff + sz_xReq);
    auth_proto = (char *) prefix + sz_xConnClientPrefix;
    auth_string = auth_proto + pad_to_int32(prefix->nbytesAuthProto);
    if ((prefix->majorVersion != X_PROTOCOL) ||
        (prefix->minorVersion != X_PROTOCOL_REVISION))
        reason = "Protocol version mismatch";
    else
        reason = ClientAuthorized(client,
                                  (unsigned short) prefix->nbytesAuthProto,
                                  auth_proto,
                                  (unsigned short) prefix->nbytesAuthString,
                                  auth_string);

    return (SendConnSetup(client, reason));
}

The product divides a value by zero.