Fix data race condition, concurrent writes to the err variable, causes Undefined Behavior

.chloggen/fix-ub-proc-helper.yaml

@@ -0,0 +1,20 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: processorhelper
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix data race condition, concurrent writes to the err variable, causes UB
+
+# One or more tracking issues or pull requests related to the change
+issues: [11350]
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

processor/processorhelper/logs.go

@@ -51,13 +51,14 @@ func NewLogs(
 		span.AddEvent("Start processing.", eventOptions)
 		recordsIn := ld.LogRecordCount()
 
-		ld, err = logsFunc(ctx, ld)
+		var errFunc error
+		ld, errFunc = logsFunc(ctx, ld)
 		span.AddEvent("End processing.", eventOptions)
-		if err != nil {
-			if errors.Is(err, ErrSkipProcessingData) {
+		if errFunc != nil {
+			if errors.Is(errFunc, ErrSkipProcessingData) {
 				return nil
 			}
-			return err
+			return errFunc
 		}
 		recordsOut := ld.LogRecordCount()
 		obs.recordInOut(ctx, recordsIn, recordsOut)

processor/processorhelper/logs_test.go

@@ -6,6 +6,7 @@ package processorhelper
 import (
 	"context"
 	"errors"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -70,6 +71,37 @@ func newTestLProcessor(retError error) ProcessLogsFunc {
 	}
 }
 
+func TestLogsConcurrency(t *testing.T) {
+	logsFunc := func(_ context.Context, ld plog.Logs) (plog.Logs, error) {
+		return ld, nil
+	}
+
+	incomingLogs := plog.NewLogs()
+	incomingLogRecords := incomingLogs.ResourceLogs().AppendEmpty().ScopeLogs().AppendEmpty().LogRecords()
+
+	// Add 3 records to the incoming
+	incomingLogRecords.AppendEmpty()
+	incomingLogRecords.AppendEmpty()
+	incomingLogRecords.AppendEmpty()
+
+	lp, err := NewLogs(context.Background(), processortest.NewNopSettings(), &testLogsCfg, consumertest.NewNop(), logsFunc)
+	require.NoError(t, err)
+	assert.NoError(t, lp.Start(context.Background(), componenttest.NewNopHost()))
+
+	var wg sync.WaitGroup
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10000; j++ {
+				assert.NoError(t, lp.ConsumeLogs(context.Background(), incomingLogs))
+			}
+		}()
+	}
+	wg.Wait()
+	assert.NoError(t, lp.Shutdown(context.Background()))
+}
+
 func TestLogs_RecordInOut(t *testing.T) {
 	// Regardless of how many logs are ingested, emit just one
 	mockAggregate := func(_ context.Context, _ plog.Logs) (plog.Logs, error) {

processor/processorhelper/metrics.go

@@ -51,13 +51,14 @@ func NewMetrics(
 		span.AddEvent("Start processing.", eventOptions)
 		pointsIn := md.DataPointCount()
 
-		md, err = metricsFunc(ctx, md)
+		var errFunc error
+		md, errFunc = metricsFunc(ctx, md)
 		span.AddEvent("End processing.", eventOptions)
-		if err != nil {
-			if errors.Is(err, ErrSkipProcessingData) {
+		if errFunc != nil {
+			if errors.Is(errFunc, ErrSkipProcessingData) {
 				return nil
 			}
-			return err
+			return errFunc
 		}
 		pointsOut := md.DataPointCount()
 		obs.recordInOut(ctx, pointsIn, pointsOut)

processor/processorhelper/metrics_test.go

@@ -6,6 +6,7 @@ package processorhelper
 import (
 	"context"
 	"errors"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -70,6 +71,36 @@ func newTestMProcessor(retError error) ProcessMetricsFunc {
 	}
 }
 
+func TestMetricsConcurrency(t *testing.T) {
+	metricsFunc := func(_ context.Context, md pmetric.Metrics) (pmetric.Metrics, error) {
+		return md, nil
+	}
+
+	incomingMetrics := pmetric.NewMetrics()
+	dps := incomingMetrics.ResourceMetrics().AppendEmpty().ScopeMetrics().AppendEmpty().Metrics().AppendEmpty().SetEmptySum().DataPoints()
+
+	// Add 2 data points to the incoming
+	dps.AppendEmpty()
+	dps.AppendEmpty()
+
+	mp, err := NewMetrics(context.Background(), processortest.NewNopSettings(), &testLogsCfg, consumertest.NewNop(), metricsFunc)
+	require.NoError(t, err)
+	assert.NoError(t, mp.Start(context.Background(), componenttest.NewNopHost()))
+
+	var wg sync.WaitGroup
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10000; j++ {
+				assert.NoError(t, mp.ConsumeMetrics(context.Background(), incomingMetrics))
+			}
+		}()
+	}
+	wg.Wait()
+	assert.NoError(t, mp.Shutdown(context.Background()))
+}
+
 func TestMetrics_RecordInOut(t *testing.T) {
 	// Regardless of how many data points are ingested, emit 3
 	mockAggregate := func(_ context.Context, _ pmetric.Metrics) (pmetric.Metrics, error) {

processor/processorhelper/traces.go

@@ -51,13 +51,14 @@ func NewTraces(
 		span.AddEvent("Start processing.", eventOptions)
 		spansIn := td.SpanCount()
 
-		td, err = tracesFunc(ctx, td)
+		var errFunc error
+		td, errFunc = tracesFunc(ctx, td)
 		span.AddEvent("End processing.", eventOptions)
-		if err != nil {
-			if errors.Is(err, ErrSkipProcessingData) {
+		if errFunc != nil {
+			if errors.Is(errFunc, ErrSkipProcessingData) {
 				return nil
 			}
-			return err
+			return errFunc
 		}
 		spansOut := td.SpanCount()
 		obs.recordInOut(ctx, spansIn, spansOut)

processor/processorhelper/traces_test.go

@@ -6,6 +6,7 @@ package processorhelper
 import (
 	"context"
 	"errors"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -70,6 +71,38 @@ func newTestTProcessor(retError error) ProcessTracesFunc {
 	}
 }
 
+func TestTracesConcurrency(t *testing.T) {
+	tracesFunc := func(_ context.Context, td ptrace.Traces) (ptrace.Traces, error) {
+		return td, nil
+	}
+
+	incomingTraces := ptrace.NewTraces()
+	incomingSpans := incomingTraces.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans()
+
+	// Add 4 records to the incoming
+	incomingSpans.AppendEmpty()
+	incomingSpans.AppendEmpty()
+	incomingSpans.AppendEmpty()
+	incomingSpans.AppendEmpty()
+
+	mp, err := NewTraces(context.Background(), processortest.NewNopSettings(), &testLogsCfg, consumertest.NewNop(), tracesFunc)
+	require.NoError(t, err)
+	assert.NoError(t, mp.Start(context.Background(), componenttest.NewNopHost()))
+
+	var wg sync.WaitGroup
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10000; j++ {
+				assert.NoError(t, mp.ConsumeTraces(context.Background(), incomingTraces))
+			}
+		}()
+	}
+	wg.Wait()
+	assert.NoError(t, mp.Shutdown(context.Background()))
+}
+
 func TestTraces_RecordInOut(t *testing.T) {
 	// Regardless of how many spans are ingested, emit just one
 	mockAggregate := func(_ context.Context, _ ptrace.Traces) (ptrace.Traces, error) {