diff --git a/services/core/java/com/android/server/notification/PreferencesHelper.java b/services/core/java/com/android/server/notification/PreferencesHelper.java
index 92ac1d48d7848..d580bd6f0a11f 100644
--- a/services/core/java/com/android/server/notification/PreferencesHelper.java
+++ b/services/core/java/com/android/server/notification/PreferencesHelper.java
@@ -73,6 +73,9 @@ public class PreferencesHelper implements RankingConfig {
     private static final int UNKNOWN_UID = UserHandle.USER_NULL;
     private static final String NON_BLOCKABLE_CHANNEL_DELIM = ":";
 
+    @VisibleForTesting
+    static final int NOTIFICATION_CHANNEL_COUNT_LIMIT = 5000;
+
     @VisibleForTesting
     static final String TAG_RANKING = "ranking";
     private static final String TAG_PACKAGE = "package";
@@ -180,6 +183,7 @@ public class PreferencesHelper implements RankingConfig {
                                     // noop
                                 }
                             }
+                            boolean skipWarningLogged = false;
 
                             PackagePreferences r = getOrCreatePackagePreferencesLocked(name, uid,
                                     XmlUtils.readIntAttribute(
@@ -226,6 +230,14 @@ public class PreferencesHelper implements RankingConfig {
                                 }
                                 // Channels
                                 if (TAG_CHANNEL.equals(tagName)) {
+                                    if (r.channels.size() >= NOTIFICATION_CHANNEL_COUNT_LIMIT) {
+                                        if (!skipWarningLogged) {
+                                            Slog.w(TAG, "Skipping further channels for " + r.pkg
+                                                    + "; app has too many");
+                                            skipWarningLogged = true;
+                                        }
+                                        continue;
+                                    }
                                     String id = parser.getAttributeValue(null, ATT_ID);
                                     String channelName = parser.getAttributeValue(null, ATT_NAME);
                                     int channelImportance = XmlUtils.readIntAttribute(
@@ -696,6 +708,10 @@ public class PreferencesHelper implements RankingConfig {
                 return needsPolicyFileChange;
             }
 
+            if (r.channels.size() >= NOTIFICATION_CHANNEL_COUNT_LIMIT) {
+                throw new IllegalStateException("Limit exceed; cannot create more channels");
+            }
+
             needsPolicyFileChange = true;
 
             if (channel.getImportance() < IMPORTANCE_NONE
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java b/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
index 8f8b746b59d49..365cd80c88c70 100644
--- a/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
@@ -22,6 +22,8 @@ import static android.app.NotificationManager.IMPORTANCE_MAX;
 import static android.app.NotificationManager.IMPORTANCE_NONE;
 import static android.app.NotificationManager.IMPORTANCE_UNSPECIFIED;
 
+import static com.android.server.notification.PreferencesHelper.NOTIFICATION_CHANNEL_COUNT_LIMIT;
+
 import static junit.framework.Assert.assertNull;
 import static junit.framework.Assert.fail;
 
@@ -2690,4 +2692,51 @@ public class PreferencesHelperTest extends UiServiceTestCase {
         assertFalse(mHelper.areBubblesAllowed(PKG_O, UID_O));
         verify(mHandler, times(1)).requestSort();
     }
+
+    @Test
+    public void testTooManyChannels() {
+        for (int i = 0; i < NOTIFICATION_CHANNEL_COUNT_LIMIT; i++) {
+            NotificationChannel channel = new NotificationChannel(String.valueOf(i),
+                    String.valueOf(i), NotificationManager.IMPORTANCE_HIGH);
+            mHelper.createNotificationChannel(PKG_O, UID_O, channel, true, true);
+        }
+        try {
+            NotificationChannel channel = new NotificationChannel(
+                    String.valueOf(NOTIFICATION_CHANNEL_COUNT_LIMIT),
+                    String.valueOf(NOTIFICATION_CHANNEL_COUNT_LIMIT),
+                    NotificationManager.IMPORTANCE_HIGH);
+            mHelper.createNotificationChannel(PKG_O, UID_O, channel, true, true);
+            fail("Allowed to create too many notification channels");
+        } catch (IllegalStateException e) {
+            // great
+        }
+    }
+
+    @Test
+    public void testTooManyChannels_xml() throws Exception {
+        String extraChannel = "EXTRA";
+        String extraChannel1 = "EXTRA1";
+
+        // create first... many... directly so we don't need a big xml blob in this test
+        for (int i = 0; i < NOTIFICATION_CHANNEL_COUNT_LIMIT; i++) {
+            NotificationChannel channel = new NotificationChannel(String.valueOf(i),
+                    String.valueOf(i), NotificationManager.IMPORTANCE_HIGH);
+            mHelper.createNotificationChannel(PKG_O, UID_O, channel, true, true);
+        }
+
+        final String xml = "<ranking version=\"1\">\n"
+                + "<package name=\"" + PKG_O + "\" uid=\"" + UID_O + "\" >\n"
+                + "<channel id=\"" + extraChannel + "\" name=\"hi\" importance=\"3\"/>"
+                + "<channel id=\"" + extraChannel1 + "\" name=\"hi\" importance=\"3\"/>"
+                + "</package>"
+                + "</ranking>";
+        XmlPullParser parser = Xml.newPullParser();
+        parser.setInput(new BufferedInputStream(new ByteArrayInputStream(xml.getBytes())),
+                null);
+        parser.nextTag();
+        mHelper.readXml(parser, false, UserHandle.USER_ALL);
+
+        assertNull(mHelper.getNotificationChannel(PKG_O, UID_O, extraChannel, true));
+        assertNull(mHelper.getNotificationChannel(PKG_O, UID_O, extraChannel1, true));
+    }
 }