The Year That Didn't Fit in an Int — Java Bug Hunt

Briefing

Modelled on Microsoft Exchange's "Y2K22" bug (1 January 2022): on-premises Exchange servers stopped delivering email at midnight on New Year's Day. The version of the malware-scanning engine's updates encodes a date as yyMMddHHmm, and it was being stored in a signed 32-bit integer; the first update of 2022, 2201010001, is larger than 2,147,483,647, so the conversion failed, the scanning engine could not load, and mail sat in the transport queues.

EngineVersion.java parses and compares those version stamps; MalwareFilter.java is the transport's gate.

Fix EngineVersion so every yyMMddHHmm version parses and compares correctly.

Bug report

BUG-Y2K22 · Priority: Critical (mail flow stopped) · Reported by: messaging ops

Engine versions are 10-digit strings "yyMMddHHmm".

• parse(v) returns the numeric value for every 10-digit version, including versions from 2022 onwards ("2201010001" -> 2201010001); anything that is not exactly 10 digits throws an IllegalArgumentException
• isNewer(a, b) is true when a's value is greater than b's
• latest(list) returns the newest version string in the list
• MalwareFilter.route(v) (locked) returns "DELIVER" for a loadable version, "QUEUED" otherwise

Observed: at 00:00 on 2022-01-01 the new engine version "2201010001" failed to load and every message stayed in the queue.

Logs

[FIPFS] Cannot convert "2201010001" to long.
[FIPFS] The FIP-FS Scan Process failed initialization.
[Transport] 18,402 messages in submission queue

The code as shipped

src/filter/EngineVersion.java (editable)

class EngineVersion {
    static int parse(String version) {
        if (version == null || version.length() != 10) {
            throw new IllegalArgumentException("bad engine version: " + version);
        }
        return Integer.parseInt(version);
    }

    static boolean isNewer(String candidate, String current) {
        return parse(candidate) > parse(current);
    }

    static String latest(List<String> versions) {
        String best = null;
        for (String v : versions) {
            if (best == null || isNewer(v, best)) best = v;
        }
        return best;
    }
}

Read-only context: src/filter/MalwareFilter.java.