diff --git a/services/core/java/com/android/server/connectivity/Vpn.java b/services/core/java/com/android/server/connectivity/Vpn.java
index c9bdcf1..2fda08e 100644
--- a/services/core/java/com/android/server/connectivity/Vpn.java
+++ b/services/core/java/com/android/server/connectivity/Vpn.java
@@ -151,6 +151,13 @@
                 .multiply(BigInteger.valueOf(howManyPercentIsMost))
                 .divide(BigInteger.valueOf(100));
     }
+    // How many routes to evaluate before bailing and declaring this Vpn should provide
+    // the INTERNET capability. This is necessary because computing the adress space is
+    // O(n²) and this is running in the system service, so a limit is needed to alleviate
+    // the risk of attack.
+    // This is taken as a total of IPv4 + IPV6 routes for simplicity, but the algorithm
+    // is actually O(n²)+O(n²).
+    private static final int MAX_ROUTES_TO_EVALUATE = 150;
 
     // TODO: create separate trackers for each unique VPN to support
     // automated reconnection
@@ -862,10 +869,12 @@
      */
     @VisibleForTesting
     static boolean providesRoutesToMostDestinations(LinkProperties lp) {
+        final List<RouteInfo> routes = lp.getAllRoutes();
+        if (routes.size() > MAX_ROUTES_TO_EVALUATE) return true;
         final Comparator<IpPrefix> prefixLengthComparator = IpPrefix.lengthComparator();
         TreeSet<IpPrefix> ipv4Prefixes = new TreeSet<>(prefixLengthComparator);
         TreeSet<IpPrefix> ipv6Prefixes = new TreeSet<>(prefixLengthComparator);
-        for (final RouteInfo route : lp.getAllRoutes()) {
+        for (final RouteInfo route : routes) {
             IpPrefix destination = route.getDestination();
             if (destination.isIPv4()) {
                 ipv4Prefixes.add(destination);
diff --git a/tests/net/java/com/android/server/connectivity/VpnTest.java b/tests/net/java/com/android/server/connectivity/VpnTest.java
index f59850d..e377a47 100644
--- a/tests/net/java/com/android/server/connectivity/VpnTest.java
+++ b/tests/net/java/com/android/server/connectivity/VpnTest.java
@@ -70,6 +70,7 @@
 import android.os.Bundle;
 import android.os.INetworkManagementService;
 import android.os.Looper;
+import android.os.SystemClock;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.support.test.filters.SmallTest;
@@ -88,6 +89,8 @@
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import java.net.Inet4Address;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -639,4 +642,32 @@
         lp.addRoute(new RouteInfo(new IpPrefix("::/1")));
         assertTrue(Vpn.providesRoutesToMostDestinations(lp));
     }
+
+    @Test
+    public void testDoesNotLockUpWithTooManyRoutes() {
+        final LinkProperties lp = new LinkProperties();
+        final byte[] ad = new byte[4];
+        // Actually evaluating this many routes under 1500ms is impossible on
+        // current hardware and for some time, as the algorithm is O(n²).
+        // Make sure the system has a safeguard against this and does not
+        // lock up.
+        final int MAX_ROUTES = 4000;
+        final long MAX_ALLOWED_TIME_MS = 1500;
+        for (int i = 0; i < MAX_ROUTES; ++i) {
+            ad[0] = (byte)((i >> 24) & 0xFF);
+            ad[1] = (byte)((i >> 16) & 0xFF);
+            ad[2] = (byte)((i >> 8) & 0xFF);
+            ad[3] = (byte)(i & 0xFF);
+            try {
+                lp.addRoute(new RouteInfo(new IpPrefix(Inet4Address.getByAddress(ad), 32)));
+            } catch (UnknownHostException e) {
+                // UnknownHostException is only thrown for an address of illegal length,
+                // which can't happen in the case above.
+            }
+        }
+        final long start = SystemClock.currentThreadTimeMillis();
+        assertTrue(Vpn.providesRoutesToMostDestinations(lp));
+        final long end = SystemClock.currentThreadTimeMillis();
+        assertTrue(end - start < MAX_ALLOWED_TIME_MS);
+    }
 }