Memory leak on HostApduService

[iPartha]

I see cumulative memory leak when app is communicating with hardware reader via NFC. I see this leak when app is running on foreground and background. I verified this leak using Leak Canary lib. I see the issue on Android 11 and 12, both are [Samsung.]

LeakTrace information

┬───
    │ GC Root: Global variable in native code
    │
    ├─ android.os.Handler$MessengerImpl instance
    │    Leaking: UNKNOWN
    │    Retaining 2.0 kB in 12 objects
    │    ↓ Handler$MessengerImpl.this$0
    │                            ~~~~~~
    ├─ android.nfc.cardemulation.HostApduService$MsgHandler instance
    │    Leaking: UNKNOWN
    │    Retaining 1.4 kB in 11 objects
    │    this$0 instance of com.example.myapplication.MyHostApduService
    │    ↓ HostApduService$MsgHandler.this$0
    │                                 ~~~~~~
    ╰→ com.example.myapplication.MyHostApduService instance
    ​     Leaking: YES (ObjectWatcher was watching this because com.example.myapplication.MyHostApduService received
    ​     Service#onDestroy() callback and Service not held by ActivityThread)
    ​     Retaining 1.4 kB in 10 objects
    ​     key = 973e5c36-af36-44a5-9f2e-9304be9a989b
    ​     watchDurationMillis = 5178
    ​     retainedDurationMillis = 174
    ​     mApplication instance of android.app.Application
    ​     mBase instance of android.app.ContextImpl
   
    METADATA
   
    Build.VERSION.SDK_INT: 29
    Build.MANUFACTURER: samsung
    LeakCanary version: 2.9.1
    App process name: com.example.myapplication
    Class count: 12221
    Instance count: 115035
    Primitive array count: 83235
    Object array count: 15185
    Thread count: 22
    Heap total bytes: 14196604
    Bitmap count: 5
    Bitmap total bytes: 79173
    Large bitmap count: 0
    Large bitmap total bytes: 0
    Db 1: open /data/user/0/com.example.myapplication/databases/leaks.db
    Stats: LruCache[maxSize=3000,hits=30041,misses=74443,hitRate=28%]
    RandomAccess[bytes=3534436,reads=74443,travel=19649182613,range=17538120,size=22508266]
    Analysis duration: 26083 ms

[pyricau]

This looks like a proper leak in the Android Framework itself. Can you file an issue on the official Android bug tracker?

HostApduService.MsgHandler is a non static inner handler class that keeps a ref to its outer class (a service) as long as the handler is alive.

https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/java/android/nfc/cardemulation/HostApduService.java;l=245;drc=a8cec413b65bfc3ea23575b34eb983c20944491b

[pyricau]

Could you repro with API 33 and then file a bug on the Google bug tracker?

[pyricau]

Going forward this leak will be reported by LeakCanary as a known library leak.