Use microcode as CPU firmware

audit/internal/collector/cpu_test.go

@@ -1,6 +1,8 @@
 package collector
 
 import (
+	"os"
+	"path/filepath"
 	"testing"
 )
 
@@ -63,6 +65,39 @@ func TestParseCPUs_unpopulated_skipped(t *testing.T) {
 	}
 }
 
+func TestCollectCPUsSetsFirmwareFromMicrocode(t *testing.T) {
+	tmp := t.TempDir()
+	origBase := cpuSysBaseDir
+	cpuSysBaseDir = tmp
+	t.Cleanup(func() { cpuSysBaseDir = origBase })
+
+	if err := os.MkdirAll(filepath.Join(tmp, "cpu0", "microcode"), 0755); err != nil {
+		t.Fatalf("mkdir microcode dir: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(tmp, "cpu0", "microcode", "version"), []byte("0x2b000643\n"), 0644); err != nil {
+		t.Fatalf("write microcode version: %v", err)
+	}
+
+	origRun := execDmidecode
+	execDmidecode = func(typeNum string) (string, error) {
+		if typeNum != "4" {
+			t.Fatalf("unexpected dmidecode type: %s", typeNum)
+		}
+		return mustReadFile(t, "testdata/dmidecode_type4.txt"), nil
+	}
+	t.Cleanup(func() { execDmidecode = origRun })
+
+	cpus := collectCPUs("CAR315KA0803B90")
+	if len(cpus) != 2 {
+		t.Fatalf("expected 2 CPUs, got %d", len(cpus))
+	}
+	for i, cpu := range cpus {
+		if cpu.Firmware == nil || *cpu.Firmware != "0x2b000643" {
+			t.Fatalf("cpu[%d] firmware=%v want microcode", i, cpu.Firmware)
+		}
+	}
+}
+
 func TestParseCPUStatus(t *testing.T) {
 	tests := []struct {
 		input string