DO NOT MERGE. No direct Uri grants from system. am: b61338ecb3

am: 30a4388481

Change-Id: I8b612304980150f522b0424e564f3bedf030c2b9

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -8203,7 +8203,12 @@ public final class ActivityManagerService extends ActivityManagerNative
 
         // Third...  does the caller itself have permission to access
         // this uri?
-        if (UserHandle.getAppId(callingUid) != Process.SYSTEM_UID) {
+        final int callingAppId = UserHandle.getAppId(callingUid);
+        if ((callingAppId == Process.SYSTEM_UID) || (callingAppId == Process.ROOT_UID)) {
+            Slog.w(TAG, "For security reasons, the system cannot issue a Uri permission"
+                    + " grant to " + grantUri + "; use startActivityAsCaller() instead");
+            return -1;
+        } else {
             if (!checkHoldingPermissionsLocked(pm, pi, grantUri, callingUid, modeFlags)) {
                 // Require they hold a strong enough Uri permission
                 if (!checkUriPermissionLocked(grantUri, callingUid, modeFlags)) {