Prevent NPE by checking SentryTracer.timer for null again inside synchronized (#2200)

adinauer · web-flow · commit 4eb446a190e7 · 2022-08-03T15:30:42.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Prevent NPE by checking SentryTracer.timer for null again inside synchronized ([#2200](https://github.com/getsentry/sentry-java/pull/2200))
 - `attach-screenshot` set on Manual init. didn't work ([#2186](https://github.com/getsentry/sentry-java/pull/2186))
 - Remove extra space from `spring.factories` causing issues in old versions of Spring Boot ([#2181](https://github.com/getsentry/sentry-java/pull/2181))
 
diff --git a/sentry/src/main/java/io/sentry/SentryTracer.java b/sentry/src/main/java/io/sentry/SentryTracer.java
@@ -64,8 +64,8 @@ public final class SentryTracer implements ITransaction {
    */
   private final @Nullable Long idleTimeout;
 
-  private @Nullable TimerTask timerTask;
-  private @Nullable Timer timer = null;
+  private volatile @Nullable TimerTask timerTask;
+  private volatile @Nullable Timer timer = null;
   private final @NotNull Object timerLock = new Object();
   private final @NotNull SpanByTimestampComparator spanByTimestampComparator =
       new SpanByTimestampComparator();
@@ -344,8 +344,10 @@ public void finish(@Nullable SpanStatus status) {
 
       if (timer != null) {
         synchronized (timerLock) {
-          timer.cancel();
-          timer = null;
+          if (timer != null) {
+            timer.cancel();
+            timer = null;
+          }
         }
       }
 
