[CDM] Validate component name length before requesting notification access.

Bug: 295335110
Test: Test app with long component name
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:618767b6bf71b872399b57eb89c6724041258f45)
Merged-In: I7ea5d5c1f78858db9865f3310d1e0aff9c8b5579
Change-Id: I7ea5d5c1f78858db9865f3310d1e0aff9c8b5579

Author: Raphael Kim

services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java

@@ -126,6 +126,7 @@ public class CompanionDeviceManagerService extends SystemService {
             "debug.cdm.cdmservice.removal_time_window";
 
     private static final long ASSOCIATION_REMOVAL_TIME_WINDOW_DEFAULT = DAYS.toMillis(90);
+    private static final int MAX_CN_LENGTH = 500;
 
     private PersistentDataStore mPersistentStore;
     private final PersistUserStateHandler mUserPersistenceHandler;
@@ -541,6 +542,9 @@ public PendingIntent requestNotificationAccess(ComponentName component, int user
             String callingPackage = component.getPackageName();
             checkCanCallNotificationApi(callingPackage);
             // TODO: check userId.
+            if (component.flattenToString().length() > MAX_CN_LENGTH) {
+                throw new IllegalArgumentException("Component name is too long.");
+            }
             final long identity = Binder.clearCallingIdentity();
             try {
                 return PendingIntent.getActivityAsUser(getContext(),