fix: More fixes to vuln matching

server/internal/vulndb/match.go

@@ -47,7 +47,7 @@ func Match(src AdvisorySource, os models.OSRelease, pkgs []models.InstalledPacka
 	cache := make(map[string][]Advisory, len(pkgs))
 
 	var out []Result
-	for _, p := range pkgs {
+	for _, p := range newestPerSource(os.Family, pkgs) {
 		// Debian and Ubuntu advisories are keyed on the source package: one
 		// advisory against "openssl" covers libssl3, openssl and libssl-dev.
 		srcName := p.SourceName
@@ -111,6 +111,61 @@ func Match(src AdvisorySource, os models.OSRelease, pkgs []models.InstalledPacka
 	return out, nil
 }
 
+// newestPerSource collapses the installed set to one binary package per source
+// package: the one carrying the highest version.
+//
+// Advisories are keyed on the source, so every binary package of a source asks
+// the same question. Normally they all carry the same version and the answer is
+// the same, so collapsing is free. The kernel is the exception that makes it
+// necessary: Ubuntu encodes the ABI in the binary name, so an upgrade INSTALLS
+// linux-headers-6.8.0-137 beside linux-headers-6.8.0-124 rather than replacing
+// it, and the old one lingers until an autoremove. Matched per binary package,
+// a fully patched host reports every superseded ABI package as vulnerable —
+// which is the noise this exists to stop — and reports it twice over, once for
+// linux-headers-6.8.0-124 and again for its -generic sibling.
+//
+// The version, not the name, decides. There is no kernel special case here: a
+// source's newest installed version is what the fix landed as, whatever the
+// source is.
+//
+// A comparison that cannot be made keeps the incumbent rather than guessing;
+// the loser is dropped either way, and dropping the parseable one would be the
+// false-negative direction.
+func newestPerSource(family string, pkgs []models.InstalledPackage) []models.InstalledPackage {
+	best := make(map[string]models.InstalledPackage, len(pkgs))
+	order := make([]string, 0, len(pkgs))
+
+	for _, p := range pkgs {
+		src := p.SourceName
+		if src == "" {
+			src = p.Name
+		}
+		cur, seen := best[src]
+		if !seen {
+			best[src] = p
+			order = append(order, src)
+			continue
+		}
+		older, err := LessThan(family, cur.Version, p.Version)
+		if err != nil {
+			log.Printf("vulndb: newest for source %s: compare %s vs %s: %v",
+				src, cur.Version, p.Version, err)
+			continue
+		}
+		if older {
+			Debugf("source %s: %s %s supersedes %s %s",
+				src, p.Name, p.Version, cur.Name, cur.Version)
+			best[src] = p
+		}
+	}
+
+	out := make([]models.InstalledPackage, 0, len(order))
+	for _, src := range order {
+		out = append(out, best[src])
+	}
+	return out
+}
+
 // actionable decides whether an advisory with no fixed version is a finding.
 //
 // trivy-db fills Status only when FixedVersion is empty, and Ubuntu publishes a