From 0940e25d0e45a2b57139219a317b7e248e0a5fd9 Mon Sep 17 00:00:00 2001
From: ian woolf <btw515wolf2@gmail.com>
Date: Wed, 19 Aug 2020 21:29:02 +0800
Subject: [PATCH] Clone value when copy fields in processors to avoid crash
 (#20500)

Closes #19206
---
 CHANGELOG.next.asciidoc                       |  1 +
 libbeat/processors/actions/copy_fields.go     | 23 ++++++++++++++++++-
 .../processors/actions/copy_fields_test.go    | 23 +++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.next.asciidoc b/CHANGELOG.next.asciidoc
index 5bc854185af..2112a664a64 100644
--- a/CHANGELOG.next.asciidoc
+++ b/CHANGELOG.next.asciidoc
@@ -244,6 +244,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Fix `cisco` asa and ftd parsing of messages 106102 and 106103. {pull}20469[20469]
 - Improve validation checks for Azure configuration {issue}20369[20369] {pull}20389[20389]
 - Fix event.kind for system/syslog pipeline {issue}20365[20365] {pull}20390[20390]
+- Clone value when copy fields in processors to avoid crash. {issue}19206[19206] {pull}20500[20500]
 
 *Heartbeat*
 
diff --git a/libbeat/processors/actions/copy_fields.go b/libbeat/processors/actions/copy_fields.go
index 44c13f41c8a..43a797e0fd5 100644
--- a/libbeat/processors/actions/copy_fields.go
+++ b/libbeat/processors/actions/copy_fields.go
@@ -104,7 +104,7 @@ func (f *copyFields) copyField(from string, to string, fields common.MapStr) err
 		return fmt.Errorf("could not fetch value for key: %s, Error: %s", from, err)
 	}
 
-	_, err = fields.Put(to, value)
+	_, err = fields.Put(to, cloneValue(value))
 	if err != nil {
 		return fmt.Errorf("could not copy value to %s: %v, %+v", to, value, err)
 	}
@@ -114,3 +114,24 @@ func (f *copyFields) copyField(from string, to string, fields common.MapStr) err
 func (f *copyFields) String() string {
 	return "copy_fields=" + fmt.Sprintf("%+v", f.config.Fields)
 }
+
+// cloneValue returns a shallow copy of a map. All other types are passed
+// through in the return. This should be used when making straight copies of
+// maps without doing any type conversions.
+func cloneValue(value interface{}) interface{} {
+	switch v := value.(type) {
+	case common.MapStr:
+		return v.Clone()
+	case map[string]interface{}:
+		return common.MapStr(v).Clone()
+	case []interface{}:
+		len := len(v)
+		newArr := make([]interface{}, len)
+		for idx, val := range v {
+			newArr[idx] = cloneValue(val)
+		}
+		return newArr
+	default:
+		return value
+	}
+}
diff --git a/libbeat/processors/actions/copy_fields_test.go b/libbeat/processors/actions/copy_fields_test.go
index 2ccbb1187b8..96b382a596a 100644
--- a/libbeat/processors/actions/copy_fields_test.go
+++ b/libbeat/processors/actions/copy_fields_test.go
@@ -122,6 +122,29 @@ func TestCopyFields(t *testing.T) {
 				"message":          42,
 			},
 		},
+		"copy map from nested key message.original to top level field message_copied": {
+			FromTo: fromTo{
+				From: "message.original",
+				To:   "message_copied",
+			},
+			Input: common.MapStr{
+				"message": common.MapStr{
+					"original": common.MapStr{
+						"original": "original",
+					},
+				},
+			},
+			Expected: common.MapStr{
+				"message": common.MapStr{
+					"original": common.MapStr{
+						"original": "original",
+					},
+				},
+				"message_copied": common.MapStr{
+					"original": "original",
+				},
+			},
+		},
 	}
 
 	for name, test := range tests {