Bug Fix: Slice out of bound in filterOfflineCpus (prometheus#534)

Signed-off-by: taherk <[email protected]>

Author: taherkk

sysfs/system_cpu.go

@@ -170,19 +170,20 @@ func binSearch(elem uint16, elemSlice *[]uint16) bool {
 	return false
 }
 
-func filterOfflineCPUs(offlineCpus *[]uint16, cpus *[]string) error {
-	for i, cpu := range *cpus {
+func filterOfflineCPUs(offlineCpus *[]uint16, cpus *[]string) ([]string, error) {
+	var filteredCPUs []string
+	for _, cpu := range *cpus {
 		cpuName := strings.TrimPrefix(filepath.Base(cpu), "cpu")
 		cpuNameUint16, err := strconv.Atoi(cpuName)
 		if err != nil {
-			return err
+			return nil, err
 		}
-		if binSearch(uint16(cpuNameUint16), offlineCpus) {
-			*cpus = append((*cpus)[:i], (*cpus)[i+1:]...)
+		if !binSearch(uint16(cpuNameUint16), offlineCpus) {
+			filteredCPUs = append(filteredCPUs, cpu)
 		}
 	}
 
-	return nil
+	return filteredCPUs, nil
 }
 
 // SystemCpufreq returns CPU frequency metrics for all CPUs.
@@ -206,7 +207,7 @@ func (fs FS) SystemCpufreq() ([]SystemCPUCpufreqStats, error) {
 		}
 
 		if len(offlineCPUs) > 0 {
-			err = filterOfflineCPUs(&offlineCPUs, &cpus)
+			cpus, err = filterOfflineCPUs(&offlineCPUs, &cpus)
 			if err != nil {
 				return nil, err
 			}

sysfs/system_cpu_test.go

@@ -35,7 +35,7 @@ func TestCPUTopology(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if want, have := 2, len(cpus); want != have {
+	if want, have := 3, len(cpus); want != have {
 		t.Errorf("incorrect number of CPUs, have %v, want %v", want, have)
 	}
 	if want, have := "0", cpus[0].Number(); want != have {
@@ -72,7 +72,7 @@ func TestCPUThermalThrottle(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if want, have := 2, len(cpus); want != have {
+	if want, have := 3, len(cpus); want != have {
 		t.Errorf("incorrect number of CPUs, have %v, want %v", want, have)
 	}
 	cpu0Throttle, err := cpus[0].ThermalThrottle()

testdata/fixtures.ttar

@@ -13152,6 +13152,9 @@ Lines: 1
 1,5
 Mode: 444
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/devices/system/cpu/cpu2
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/sys/devices/system/cpu/cpufreq
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -13228,7 +13231,7 @@ Mode: 664
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Path: fixtures/sys/devices/system/cpu/offline
 Lines: 1
-2,12-15
+2
 Mode: 664
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/sys/devices/system/node