[permission] Debugging access state concurrency

Add a fail fast check to ensure that we aren't accidentally mutating an
an object which is reachable from old state. This shouldn't happen, but
we are getting ConcurrentException in ArrayMap.

Bug: 401768134
Test: boot
Flag: EXEMPT debugging
Change-Id: I00c122200d48bd18197745e7c80e7d729361215d

1 files changed, 7 insertions, 0 deletions

diff --git a/services/permission/java/com/android/server/permission/access/permission/AppIdPermissionPolicy.kt b/services/permission/java/com/android/server/permission/access/permission/AppIdPermissionPolicy.kt
index 232bb83fdf9f..5a140d53a4d8 100644
--- a/services/permission/java/com/android/server/permission/access/permission/AppIdPermissionPolicy.kt
+++ b/services/permission/java/com/android/server/permission/access/permission/AppIdPermissionPolicy.kt
@@ -1753,6 +1753,13 @@ class AppIdPermissionPolicy : SchemePolicy() {
         }
         val appIdPermissionFlags = newState.mutateUserState(userId)!!.mutateAppIdPermissionFlags()
         val permissionFlags = appIdPermissionFlags.mutateOrPut(appId) { MutableIndexedMap() }
+        // for debugging possible races TODO(b/401768134)
+        oldState.userStates[userId]?.appIdPermissionFlags[appId]?.map?.let {
+            if (permissionFlags.map === it) {
+                throw IllegalStateException("Unexpected sharing between old/new state")
+            }
+        }
+
         permissionFlags.putWithDefault(permissionName, newFlags, 0)
         if (permissionFlags.isEmpty()) {
             appIdPermissionFlags -= appId