[metricbeat/prometheus] Add panic recovery for Prometheus textparser

metricbeat/helper/prometheus/textparse.go

@@ -310,7 +310,7 @@ func (m *MetricFamily) GetName() string {
 	return ""
 }
 func (m *MetricFamily) GetUnit() string {
-	if m != nil && *m.Unit != "" {
+	if m != nil && m.Unit != nil && *m.Unit != "" {
 		return *m.Unit
 	}
 	return ""
@@ -506,6 +506,37 @@ func ParseMetricFamilies(b []byte, contentType string, ts time.Time, logger *log
 		metricTypes = make(map[string]model.MetricType)
 	)
 
+	safeExemplar := func(e *exemplar.Exemplar) bool {
+		var hasExemplar bool
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					if logger != nil {
+						logger.Debugf("Recovered from panic while parsing exemplar: %v", r)
+					}
+				}
+			}()
+			hasExemplar = parser.Exemplar(e)
+		}()
+		return hasExemplar
+	}
+
+	safeLabels := func(lset *labels.Labels) bool {
+		var labelsRecovered bool
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					labelsRecovered = true
+					if logger != nil {
+						logger.Debugf("Recovered from panic while parsing labels: %v", r)
+					}
+				}
+			}()
+			parser.Labels(lset)
+		}()
+		return !labelsRecovered
+	}
+
 	for {
 		var (
 			et textparse.Entry
@@ -580,7 +611,9 @@ func ParseMetricFamilies(b []byte, contentType string, ts time.Time, logger *log
 		_, tp, v := parser.Series()
 
 		var lset labels.Labels
-		parser.Labels(&lset)
+		if !safeLabels(&lset) {
+			continue
+		}
 		metadata := schema.NewMetadataFromLabels(lset)
 		metricName := metadata.Name
 
@@ -683,7 +716,7 @@ func ParseMetricFamilies(b []byte, contentType string, ts time.Time, logger *log
 				continue
 			}
 		case model.MetricTypeHistogram:
-			if hasExemplar := parser.Exemplar(&e); hasExemplar {
+			if hasExemplar := safeExemplar(&e); hasExemplar {
 				exm = &e
 			}
 			lookupMetricName, metric = histogramMetricName(metricName, v, qv, lbls.String(), &t, false, exm, histogramsByName)
@@ -696,7 +729,7 @@ func ParseMetricFamilies(b []byte, contentType string, ts time.Time, logger *log
 				continue
 			}
 		case model.MetricTypeGaugeHistogram:
-			if hasExemplar := parser.Exemplar(&e); hasExemplar {
+			if hasExemplar := safeExemplar(&e); hasExemplar {
 				exm = &e
 			}
 			lookupMetricName, metric = histogramMetricName(metricName, v, qv, lbls.String(), &t, true, exm, histogramsByName)
@@ -733,7 +766,7 @@ func ParseMetricFamilies(b []byte, contentType string, ts time.Time, logger *log
 			}
 		}
 
-		if hasExemplar := parser.Exemplar(&e); hasExemplar && mt != model.MetricTypeHistogram && metric != nil {
+		if hasExemplar := safeExemplar(&e); hasExemplar && mt != model.MetricTypeHistogram && metric != nil {
 			if !e.HasTs {
 				e.Ts = t
 			}

metricbeat/helper/prometheus/textparse_fuzz_test.go

@@ -0,0 +1,127 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package prometheus
+
+import (
+	"testing"
+	"time"
+
+	"github.com/elastic/elastic-agent-libs/logp"
+)
+
+func FuzzParseMetricFamilies(f *testing.F) {
+	seeds := [][]byte{
+		// Valid metrics
+		[]byte("# TYPE http_requests counter\nhttp_requests 100\n"),
+		[]byte("# TYPE http_requests_total counter\nhttp_requests_total 100\n"),
+		[]byte("# TYPE temperature gauge\ntemperature 23.5\n"),
+		[]byte("# TYPE temperature gauge\ntemperature{location=\"room1\"} 23.5\n"),
+		[]byte(`# TYPE http_duration histogram
+http_duration_bucket{le="0.1"} 10
+http_duration_bucket{le="0.5"} 50
+http_duration_bucket{le="+Inf"} 100
+http_duration_sum 35.5
+http_duration_count 100
+`),
+		[]byte(`# TYPE rpc_duration summary
+rpc_duration{quantile="0.5"} 0.05
+rpc_duration{quantile="0.9"} 0.08
+rpc_duration{quantile="0.99"} 0.1
+rpc_duration_sum 17.5
+rpc_duration_count 200
+`),
+		[]byte("# TYPE custom_metric unknown\ncustom_metric 42\n"),
+		[]byte("metric_without_type 42\n"),
+
+		// OpenMetrics
+		[]byte("# TYPE http_requests counter\nhttp_requests_total 100\nhttp_requests_created 1234567890\n# EOF\n"),
+		[]byte("# TYPE build info\nbuild_info{version=\"1.0\",commit=\"abc123\"} 1\n# EOF\n"),
+		[]byte("# TYPE feature stateset\nfeature{feature=\"a\"} 1\nfeature{feature=\"b\"} 0\n# EOF\n"),
+		[]byte(`# TYPE request_size gaugehistogram
+request_size_gcount 100
+request_size_gsum 12345
+request_size_bucket{le="100"} 10
+request_size_bucket{le="+Inf"} 100
+# EOF
+`),
+
+		// Exemplars
+		[]byte("# TYPE http_requests counter\nhttp_requests_total 100 # {trace_id=\"abc\"} 1.0\n# EOF\n"),
+		[]byte("# TYPE http_requests counter\nhttp_requests_total 100 # {trace_id=\"abc\",span_id=\"def\"} 1.0 123456\n# EOF\n"),
+		[]byte("# TYPE http_duration histogram\nhttp_duration_bucket{le=\"1\"} 10 # {trace_id=\"xyz\"} 0.9\n# EOF\n"),
+
+		// Metadata
+		[]byte("# HELP http_requests Total HTTP requests\n# TYPE http_requests counter\nhttp_requests 100\n"),
+		[]byte("# TYPE temperature gauge\n# UNIT temperature celsius\ntemperature 23.5\n# EOF\n"),
+
+		// Timestamps and labels
+		[]byte("metric_with_ts 100 1234567890\n"),
+		[]byte("metric_with_ts{label=\"value\"} 100 1234567890\n"),
+		[]byte("metric{a=\"1\",b=\"2\",c=\"3\",d=\"4\"} 100\n"),
+
+		// Special values
+		[]byte("metric_nan NaN\n"),
+		[]byte("metric_inf +Inf\n"),
+		[]byte("metric_neginf -Inf\n"),
+
+		// Edge cases
+		nil,
+		{},
+		[]byte("\n"),
+
+		// Malformed labels
+		[]byte("metric{"),
+		[]byte("metric{label}"),
+		[]byte("metric{label=}"),
+		[]byte("metric{label=\""),
+
+		// Known crash inputs
+		[]byte("{A}0"),
+		[]byte("{A}00"),
+		[]byte("{A}000"),
+		[]byte("{A}0000"),
+		[]byte("{A} 1"),
+		[]byte("{A} 1\n"),
+		[]byte("{A}0\n"),
+		[]byte("{A}0 1"),
+		[]byte("{A}0 1\n"),
+		[]byte("{A}0\n000"),
+		[]byte("{A}00\n"),
+		[]byte("{A}00000"),
+		[]byte("{A}00 1"),
+		[]byte("{A}00 1\n"),
+		[]byte("{A}00\n000"),
+
+		// Malformed exemplars
+		[]byte("# TYPE c counter\nc_total 10 # {}\n# EOF\n"),
+		[]byte("# TYPE c counter\nc_total 10 # {\n# EOF\n"),
+		[]byte("# TYPE c counter\nc_total 10 # {a=}\n# EOF\n"),
+	}
+
+	for _, seed := range seeds {
+		f.Add(seed)
+	}
+
+	logger := logp.NewLogger("fuzz")
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		_, _ = ParseMetricFamilies(data, ContentTypeTextFormat, time.Now(), logger)
+		_, _ = ParseMetricFamilies(data, OpenMetricsType, time.Now(), logger)
+		_, _ = ParseMetricFamilies(data, "", time.Now(), logger)
+	})
+}