From d557f547fa93a7fa52e588917ec5186a050b3da3 Mon Sep 17 00:00:00 2001
From: kezhenxu94 <kezhenxu94@apache.org>
Date: Thu, 2 Dec 2021 22:08:40 +0800
Subject: [PATCH] Fix potential NPE in OAL string match and a bug when
 right-hand-side variable includes double quotes (#8234)

---
 CHANGES.md                                                  | 1 +
 .../core/analysis/metrics/expression/StringMatch.java       | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index ea23d75eb0..1c943af606 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -10,6 +10,7 @@ Release Notes.
 
 #### OAP Server
 
+* Fix potential NPE in OAL string match and a bug when right-hand-side variable includes double quotes.
 
 #### UI
 
diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/metrics/expression/StringMatch.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/metrics/expression/StringMatch.java
index d0b6b01825..9f931fb625 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/metrics/expression/StringMatch.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/metrics/expression/StringMatch.java
@@ -25,12 +25,12 @@ import org.apache.skywalking.oap.server.core.analysis.metrics.annotation.FilterM
 public class StringMatch {
 
     public boolean match(String left, String right) {
-        if (left.startsWith("\"") && left.endsWith("\"")) {
+        if (left != null && left.startsWith("\"") && left.endsWith("\"")) {
             left = left.substring(1, left.length() - 1);
         }
 
-        if (right.startsWith("\"") && right.endsWith("\"")) {
-            right = left.substring(1, right.length() - 1);
+        if (right != null && right.startsWith("\"") && right.endsWith("\"")) {
+            right = right.substring(1, right.length() - 1);
         }
 
         return Objects.equals(left, right);