My team uses a broadly used WinRT API. Basically, all apps that have a device-related scenario use it. This means buggy apps that crash will sometimes have our component featured in their Watson dumps. Based on certain metrics, Watson will turn buckets turn into code bugs, so we have to triage them. Aside: in case you were wondering, bugs from WER (Windows Error Reporting) service and dumps, do generate bugs and get fixed, so WER is useful.
A number of AV crash bugs we see are related to our device watcher calling back into the app's handlers for the device events, which almost always means a lifetime management bug in the app.
You can check the memory allocations to see if they are busy or free. This applies more to the component that owns the object's memory. I think I covered that before. That will let you know if the object has already been released. A lot of times you can still see the object's state after it has been freed, but the important part is that it has been released/freed already, so the object is not being ref counted correctly. AppVerif has a handy COM set of checks which might help if you think you may have this problem in your code. With smart pointers, it can be a little harder to see what is happening with the object's references. If the object model is not too complicated, you can just find the bug with code inspection.
A super common reason for AVs like this is the DLL is unloaded. COM aggressively unloads DLLs not being used by calling DllCanUnloadNow. If the implementation has a bug, the DLL will get unloaded while objects and other COM operations are in flight. Eventually, when COM tries to CoUnitialize an object that belongs to that DLL, it will AV. This also applies to other COM things like when COM tries to marshal between apartments, etc.
We see crashes like this fairly often:
0:049> .excr rax=00007ff8f305cf70 rbx=0000026dfc5cc900 rcx=0000026dfc5cc900 rdx=0000000000012f06 rsi=0000026dfa091b00 rdi=0000026dfa091ae0 rip=00007ff990c9094d rsp=000000b92deff490 rbp=00000000800401fd r8=00007ff970a0b370 r9=000000b92deff5d0 r10=dee01e7974d59970 r11=000000b92deff5e0 r12=0000000000012f06 r13=00007ff970a0b370 r14=000000b92deff5d0 r15=00007ff8f305cf70 iopl=0 nv up ei pl nz na pe nc cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202 combase!CGIPTable::GetRequestedInterface+0x22 [inlined in combase!CGIPTable::GetInterfaceFromGlobal+0x1ed]: 00007ff9`90c9094d 488b00 mov rax,qword ptr [rax] ds:00007ff8`f305cf70=???????????????? 0:049> k *** Stack trace for last set context - .thread/.cxr resets it # Child-SP RetAddr Call Site 00 (Inline Function) --------`-------- combase!CGIPTable::GetRequestedInterface+0x22 [onecore\com\combase\dcomrem\giptbl.cxx @ 1615] 01 000000b9`2deff490 00007ff9`7097515b combase!CGIPTable::GetInterfaceFromGlobal+0x1ed [onecore\com\combase\dcomrem\giptbl.cxx @ 1660] 02 000000b9`2deff560 00007ff9`70977823 Windows_Devices_Enumeration!Gip<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *> >::Localize+0x6b [onecore\private\base\inc\devices\Git.h @ 167] 03 (Inline Function) --------`-------- Windows_Devices_Enumeration!GitDelegate2<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *>,Windows::Devices::Enumeration::IDeviceWatcher *,Windows::Devices::Enumeration::IDeviceInformation *>::GetHandler+0x11 [onecoreuap\base\devices\rtenum\dllsrv\GitDelegate.h @ 254] 04 000000b9`2deff5a0 00007ff9`70976d95 Windows_Devices_Enumeration!GitDelegate2<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *>,Windows::Devices::Enumeration::IDeviceWatcher *,Windows::Devices::Enumeration::IDeviceInformation *>::Invoke+0x23 [onecoreuap\base\devices\rtenum\dllsrv\GitDelegate.h @ 303] 05 (Inline Function) --------`-------- Windows_Devices_Enumeration!Microsoft::WRL::EventSource<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *>,Microsoft::WRL::InvokeModeOptions<-2> >::InvokeAll::__l2::<lambda_00d1300cb6cb75d6b2b5344e37267964>::operator()+0x36 [onecore\external\sdk\inc\wrl\event.h @ 964] 06 000000b9`2deff5d0 00007ff9`70976cf4 Windows_Devices_Enumeration!Microsoft::WRL::InvokeTraits<-2>::InvokeDelegates<<lambda_00d1300cb6cb75d6b2b5344e37267964>,Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *> >+0x79 [onecore\internal\sdk\inc\wrl\internalevent.h @ 121] 07 000000b9`2deff630 00007ff9`70981d3d Windows_Devices_Enumeration!Microsoft::WRL::EventSource<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *>,Microsoft::WRL::InvokeModeOptions<-2> >::DoInvoke<<lambda_00d1300cb6cb75d6b2b5344e37267964> >+0x78 [onecore\external\sdk\inc\wrl\event.h @ 954] 08 (Inline Function) --------`-------- Windows_Devices_Enumeration!Microsoft::WRL::EventSource<Windows::Foundation::ITypedEventHandler<Windows::Devices::Enumeration::DeviceWatcher *,Windows::Devices::Enumeration::DeviceInformation *>,Microsoft::WRL::InvokeModeOptions<-2> >::InvokeAll+0x19 [onecore\external\sdk\inc\wrl\event.h @ 964] 09 000000b9`2deff670 00007ff9`8ee2d946 Windows_Devices_Enumeration!Watcher<Windows::Devices::Enumeration::DeviceWatcher,Windows::Devices::Enumeration::IDeviceWatcher,Windows::Devices::Enumeration::IDeviceWatcher2,Windows::Devices::Enumeration::DeviceInformation,Windows::Devices::Enumeration::IDeviceInformation,Windows::Devices::Enumeration::IDeviceInformation2,DeviceInformationServer,Windows::Devices::Enumeration::DeviceInformationUpdate,Windows::Devices::Enumeration::IDeviceInformationUpdate,DeviceInformationUpdateServer,&RuntimeClass_Windows_Devices_Enumeration_DeviceWatcher>::Impl::DevQueryCallback+0x3ad [onecoreuap\base\devices\rtenum\dllsrv\Watcher.h @ 889] 0a 000000b9`2deff710 00007ff9`91b9b0ea cfgmgr32!TQuery::ServiceActionQueue+0xe2 [onecore\base\pnp\devquery\lib\query.cpp @ 245] 0b 000000b9`2deff7a0 00007ff9`91b3ec06 ntdll!TppWorkpExecuteCallback+0x13a [minkernel\threadpool\ntdll\work.c @ 671] 0c 000000b9`2deff7f0 00007ff9`8ff94ede ntdll!TppWorkerThread+0x686 [minkernel\threadpool\ntdll\worker.c @ 1109] 0d 000000b9`2deffae0 00007ff9`91b87c6b kernel32!BaseThreadInitThunk+0x1e [clientcore\base\win32\client\thread.c @ 70] 0e 000000b9`2deffb10 00000000`00000000 ntdll!RtlUserThreadStart+0x2b [minkernel\ntdll\rtlstrt.c @ 1152] 0:049> .frame 0n0;dv /t /v 00 (Inline Function) --------`-------- combase!CGIPTable::GetRequestedInterface+0x22 [onecore\com\combase\dcomrem\giptbl.cxx @ 1615] @rbx struct IUnknown * pUnk = 0x0000026d`fc5cc900 @r15 void * pVtableAddress = 0x00007ff8`f305cf70 <unavailable> HRESULT hr = <value unavailable> 0:049> dps 0x0000026d`fc5cc900 0000026d`fc5cc900 00007ff8`f305cf70 <Unloaded_xxxxxxxxx.dll>+0xc2cf70 0000026d`fc5cc908 00000001`00000000 0000026d`fc5cc910 0000026d`fbdc9af0 0000026d`fc5cc918 00080000`00000000 0000026d`fc5cc920 00000000`00000008 0000026d`fc5cc928 00000008`4d454d4c 0000026d`fc5cc930 0000026d`fc4d3bf8
You can see that the handler's dll is already unloaded.
// or another example ///
:000> k combase!CStdMarshal::DisconnectSrvIPIDs::__l29::<lambda_2a3a7b5175b0a5e47c77e1d8eff078e5>::operator()+0x7 combase!ObjectMethodExceptionHandlingAction<<lambda_2a3a7b5175b0a5e47c77e1d8eff078e5> >+0x24 combase!CStdMarshal::DisconnectSrvIPIDs+0x30d combase!CStdMarshal::DisconnectWorker_ReleasesLock+0x2d7 combase!CStdMarshal::DisconnectSwitch_ReleasesLock+0x1c combase!CStdMarshal::DisconnectAndReleaseWorker_ReleasesLock+0x32 combase!COIDTable::ThreadCleanup+0x117 combase!FinishShutdown::__l2::<lambda_3d4acc620ec77839d81caec938b15158>::operator()+0x5 combase!ObjectMethodExceptionHandlingAction<<lambda_3d4acc620ec77839d81caec938b15158> >+0x9 combase!FinishShutdown+0x78 combase!ApartmentUninitialize+0xc9 combase!wCoUninitialize+0x17d combase!CoUninitialize+0xea wuaueng!UHRunRemoteHandlerServer+0x25e ...
0:000> .exr -1 ExceptionAddress: 00007ffe8571a510 (combase!CStdMarshal::DisconnectSrvIPIDs::__l29::<lambda_2a3a7b5175b0a5e47c77e1d8eff078e5>::operator()+0x0000000000000007) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Attempt to read from address 00007ffe59d74ee8 0:000> ln 00007ffe59d74ee8 (00007ffe`59d74ee8) <Unloaded_xxxxxxxxxxx.dll>+0x1b4ee8
