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Commit 213049e6 authored by Fabian Kozynski's avatar Fabian Kozynski
Browse files

Ensure that maps are only accessed in BG thread 

If the maps are accessed from main thread (as well as bg thread), they
could be in an inconsistent state. In particular they could have nulls
for non-nullable types.

This CL asserts that createFilter is only called in BG thread. It also
makes sure that only non-nulls are passed to IntentFilter#addAction.

Test: atest UserBroadcastDispatcherTest
Fixes: 144039089
Change-Id: I58e66bc9a861c70c830fcbd4476d6dfc991c4ad0
parent 98e9bbdb

packages/SystemUI/src/com/android/systemui/broadcast/UserBroadcastDispatcher.kt

+51 −23
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ import android.os.UserHandle 
import android.util.ArrayMap

import android.util.ArraySet

import android.util.Log

import androidx.annotation.MainThread

import com.android.internal.util.Preconditions

import com.android.systemui.Dumpable

import java.io.FileDescriptor

import java.io.PrintWriter
@@ -72,7 +74,14 @@ class UserBroadcastDispatcher( 


    internal fun isRegistered() = registered.get()



    private val registerReceiver = Runnable {

    // Only modify in BG thread

    private val actionsToReceivers = ArrayMap<String, MutableSet<ReceiverData>>()

    private val receiverToReceiverData = ArrayMap<BroadcastReceiver, MutableSet<ReceiverData>>()



    // Only call on BG thread as it reads from the maps

    private fun createFilter(): IntentFilter {

        Preconditions.checkState(bgHandler.looper.isCurrentThread,

                "This method should only be called from BG thread")

        val categories = mutableSetOf<String>()

        receiverToReceiverData.values.flatten().forEach {

            it.filter.categoriesIterator()?.asSequence()?.let {
@@ -80,30 +89,13 @@ class UserBroadcastDispatcher( 
            }

        }

        val intentFilter = IntentFilter().apply {

            actionsToReceivers.keys.forEach { addAction(it) }

            // The keys of the arrayMap are of type String! so null check is needed

            actionsToReceivers.keys.forEach { if (it != null) addAction(it) else Unit }

            categories.forEach { addCategory(it) }

        }



        if (registered.get()) {

            context.unregisterReceiver(this)

            registered.set(false)

        }

        // Short interval without receiver, this can be problematic

        if (intentFilter.countActions() > 0 && !registered.get()) {

            context.registerReceiverAsUser(

                    this,

                    UserHandle.of(userId),

                    intentFilter,

                    null,

                    bgHandler)

            registered.set(true)

        }

        return intentFilter

    }



    // Only modify in BG thread

    private val actionsToReceivers = ArrayMap<String, MutableSet<ReceiverData>>()

    private val receiverToReceiverData = ArrayMap<BroadcastReceiver, MutableSet<ReceiverData>>()



    override fun onReceive(context: Context, intent: Intent) {

        val id = if (DEBUG) index.getAndIncrement() else 0

        if (DEBUG) Log.w(TAG, "[$id] Received $intent")
@@ -126,6 +118,8 @@ class UserBroadcastDispatcher( 
    }



    private fun handleRegisterReceiver(receiverData: ReceiverData) {

        Preconditions.checkState(bgHandler.looper.isCurrentThread,

                "This method should only be called from BG thread")

        if (DEBUG) Log.w(TAG, "Register receiver: ${receiverData.receiver}")

        receiverToReceiverData.getOrPut(receiverData.receiver, { ArraySet() }).add(receiverData)

        var changed = false
@@ -138,11 +132,13 @@ class UserBroadcastDispatcher( 
            }.add(receiverData)

        }

        if (changed) {

            mainHandler.post(registerReceiver)

            createFilterAndRegisterReceiverBG()

        }

    }



    private fun handleUnregisterReceiver(receiver: BroadcastReceiver) {

        Preconditions.checkState(bgHandler.looper.isCurrentThread,

                "This method should only be called from BG thread")

        if (DEBUG) Log.w(TAG, "Unregister receiver: $receiver")

        val actions = receiverToReceiverData.getOrElse(receiver) { return }

                .flatMap { it.filter.actionsIterator().asSequence().asIterable() }.toSet()
@@ -156,10 +152,16 @@ class UserBroadcastDispatcher( 
            }

        }

        if (changed) {

            mainHandler.post(registerReceiver)

            createFilterAndRegisterReceiverBG()

        }

    }



    // Only call this from a BG thread

    private fun createFilterAndRegisterReceiverBG() {

        val intentFilter = createFilter()

        mainHandler.post(RegisterReceiverRunnable(intentFilter))

    }



    override fun dump(fd: FileDescriptor, pw: PrintWriter, args: Array<out String>) {

        pw.println("  Registered=${registered.get()}")

        actionsToReceivers.forEach { (action, list) ->
@@ -191,4 +193,30 @@ class UserBroadcastDispatcher( 
                    }

        }

    }



    private inner class RegisterReceiverRunnable(val intentFilter: IntentFilter) : Runnable {



        /*

         * Registers and unregisters the BroadcastReceiver

         *

         * Must be called from Main Thread

         */

        @MainThread

        override fun run() {

            if (registered.get()) {

                context.unregisterReceiver(this@UserBroadcastDispatcher)

                registered.set(false)

            }

            // Short interval without receiver, this can be problematic

            if (intentFilter.countActions() > 0 && !registered.get()) {

                context.registerReceiverAsUser(

                        this@UserBroadcastDispatcher,

                        UserHandle.of(userId),

                        intentFilter,

                        null,

                        bgHandler)

                registered.set(true)

            }

        }

    }

}