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Commit acd43218 authored by Mike Lockwood's avatar Mike Lockwood
Browse files

MidiDeviceServer: Fix race condition in setting device server's mDeviceInfo 

This made it unsafe to open ports on a device from the MidiManager onDeviceOpened callback

Bug: 21760692
Change-Id: I536acdf574a3ccecdb66a8fde87089538e8bb1ef
parent 6d5a0f91

media/java/android/media/midi/IMidiDeviceServer.aidl

+1 −0
Original line number Diff line number Diff line
@@ -31,4 +31,5 @@ interface IMidiDeviceServer 
    void connectPorts(IBinder token, in ParcelFileDescriptor pfd, int outputPortNumber);



    MidiDeviceInfo getDeviceInfo();

    void setDeviceInfo(in MidiDeviceInfo deviceInfo);

}

media/java/android/media/midi/MidiDeviceServer.java

+19 −7
Original line number Diff line number Diff line
@@ -269,8 +269,20 @@ public final class MidiDeviceServer implements Closeable { 
        public MidiDeviceInfo getDeviceInfo() {

            return mDeviceInfo;

        }



        @Override

        public void setDeviceInfo(MidiDeviceInfo deviceInfo) {

            if (Binder.getCallingUid() != Process.SYSTEM_UID) {

                throw new SecurityException("setDeviceInfo should only be called by MidiService");

            }

            if (mDeviceInfo != null) {

                throw new IllegalStateException("setDeviceInfo should only be called once");

            }

            mDeviceInfo = deviceInfo;

        }

    };



    // Constructor for MidiManager.createDeviceServer()

    /* package */ MidiDeviceServer(IMidiManager midiManager, MidiReceiver[] inputPortReceivers,

            int numOutputPorts, Callback callback) {

        mMidiManager = midiManager;
@@ -292,6 +304,13 @@ public final class MidiDeviceServer implements Closeable { 
        mGuard.open("close");

    }



    // Constructor for MidiDeviceService.onCreate()

    /* package */ MidiDeviceServer(IMidiManager midiManager, MidiReceiver[] inputPortReceivers,

           MidiDeviceInfo deviceInfo, Callback callback) {

        this(midiManager, inputPortReceivers, deviceInfo.getOutputPortCount(), callback);

        mDeviceInfo = deviceInfo;

    }



    /* package */ IMidiDeviceServer getBinderInterface() {

        return mServer;

    }
@@ -300,13 +319,6 @@ public final class MidiDeviceServer implements Closeable { 
        return mServer.asBinder();

    }



    /* package */ void setDeviceInfo(MidiDeviceInfo deviceInfo) {

        if (mDeviceInfo != null) {

            throw new IllegalStateException("setDeviceInfo should only be called once");

        }

        mDeviceInfo = deviceInfo;

    }



    private void updateDeviceStatus() {

        // clear calling identity, since we may be in a Binder call from one of our clients

        long identityToken = Binder.clearCallingIdentity();

media/java/android/media/midi/MidiDeviceService.java

+1 −3
Original line number Diff line number Diff line
@@ -83,9 +83,7 @@ abstract public class MidiDeviceService extends Service { 
            if (inputPortReceivers == null) {

                inputPortReceivers = new MidiReceiver[0];

            }

            server = new MidiDeviceServer(mMidiManager, inputPortReceivers,

                    deviceInfo.getOutputPortCount(), mCallback);

            server.setDeviceInfo(deviceInfo);

            server = new MidiDeviceServer(mMidiManager, inputPortReceivers, deviceInfo, mCallback);

        } catch (RemoteException e) {

            Log.e(TAG, "RemoteException in IMidiManager.getServiceDeviceInfo");

            server = null;

media/java/android/media/midi/MidiManager.java

+0 −1
Original line number Diff line number Diff line
@@ -318,7 +318,6 @@ public final class MidiManager { 
                Log.e(TAG, "registerVirtualDevice failed");

                return null;

            }

            server.setDeviceInfo(deviceInfo);

            return server;

        } catch (RemoteException e) {

            Log.e(TAG, "RemoteException in createVirtualDevice");

services/midi/java/com/android/server/midi/MidiService.java

+9 −0
Original line number Diff line number Diff line
@@ -741,6 +741,15 @@ public class MidiService extends IMidiManager.Stub { 
        MidiDeviceInfo deviceInfo = new MidiDeviceInfo(type, id, numInputPorts, numOutputPorts,

                inputPortNames, outputPortNames, properties, isPrivate);



        if (server != null) {

            try {

                server.setDeviceInfo(deviceInfo);

            } catch (RemoteException e) {

                Log.e(TAG, "RemoteException in setDeviceInfo()");

                return null;

            }

        }



        Device device = null;

        BluetoothDevice bluetoothDevice = null;

        if (type == MidiDeviceInfo.TYPE_BLUETOOTH) {