Crash Dump Analysis Patterns (Part 90)

Sometimes we have a managed code exception that was enveloping a handled unmanaged code exception, Mixed (Nested) Exception:

0:000> !analyze -v


EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00000000
   ExceptionCode: 80000003 (Break instruction exception)
  ExceptionFlags: 00000000
NumberParameters: 0

ERROR_CODE: (NTSTATUS) 0x80000003 - {EXCEPTION}  Breakpoint  A breakpoint has been reached.



EXCEPTION_OBJECT: !pe 1f9af1ac
Exception object: 1f9af1ac
Exception type: System.AccessViolationException
Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
InnerException: <none>
StackTrace (generated):
    SP       IP       Function
    0012EF3C 28DD9AF9 DllA!Component.getFirstField()+0×11
    0012EFC8 7B194170 System_Windows_Forms_ni!System.Windows.Forms.Control.OnClick(System.EventArgs)+0×70
    0012EFE0 7B6F74B4 System_Windows_Forms_ni!System.Windows.Forms.Control.WmMouseUp(System.Windows.Forms.Message ByRef, System.Windows.Forms.MouseButtons, Int32)+0×170
    0012F06C 7BA29B66 System_Windows_Forms_ni!System.Windows.Forms.Control.WndProc(System.Windows.Forms.Message ByRef)+0×861516
    0012F0C4 7B1D1D6A System_Windows_Forms_ni!System.Windows.Forms.ScrollableControl.WndProc(System.Windows.Forms.Message ByRef)+0×2a
    0012F0D0 7B1C8640 System_Windows_Forms_ni!System.Windows.Forms.Control+ControlNativeWindow.OnMessage(System.Windows.Forms.Message ByRef)+0×10
    0012F0D8 7B1C85C1 System_Windows_Forms_ni!System.Windows.Forms.Control+ControlNativeWindow.WndProc(System.Windows.Forms.Message ByRef)+0×31
    0012F0EC 7B1C849A System_Windows_Forms_ni!System.Windows.Forms.NativeWindow.Callback(IntPtr, Int32, IntPtr, IntPtr)+0×5a


We see that it was the access violation exception and check the thread with TID cfc:

0:000> kL
ChildEBP RetAddr 
0012db54 77d70dde ntdll!KiFastSystemCallRet
0012db58 7b1d8e48 user32!NtUserWaitMessage+0xc
0012dbec 7b1d8937 System_Windows_Forms_ni+0x208e48
0012dc44 7b1d8781 System_Windows_Forms_ni+0x208937
0012dc74 7b6edd1f System_Windows_Forms_ni+0x208781
0012dc8c 7b72246b System_Windows_Forms_ni+0x71dd1f
0012dd18 7b722683 System_Windows_Forms_ni+0x75246b
0012dd58 7b6f77f6 System_Windows_Forms_ni+0x752683
0012dd64 7b6fa27c System_Windows_Forms_ni+0x7277f6
0012f148 77d6f8d2 System_Windows_Forms_ni+0x72a27c
0012f174 77d6f794 user32!InternalCallWinProc+0x23
0012f1ec 77d70008 user32!UserCallWinProcCheckWow+0x14b
0012f250 77d70060 user32!DispatchMessageWorker+0x322
0012f260 0a1412fa user32!DispatchMessageW+0xf
WARNING: Frame IP not in any known module. Following frames may be wrong.
0012f27c 578439f7 0xa1412fa
0012f2ec 578430c9 WindowsBase_ni+0x939f7
0012f2f8 5784306c WindowsBase_ni+0x930c9
0012f304 55bed46e WindowsBase_ni+0x9306c
0012f310 55bec76f PresentationFramework_ni+0x1cd46e
0012f334 55bd3aa6 PresentationFramework_ni+0x1cc76f

If there was an exception it must be hidden so we inspect the thread raw stack:

0:000> !teb
TEB at 7ffdf000
    ExceptionList:        0012e470
    StackBase:            00130000
    StackLimit:           0011e000

    SubSystemTib:         00000000
    FiberData:            00001e00
    ArbitraryUserPointer: 00000000
    Self:                 7ffdf000
    EnvironmentPointer:   00000000
    ClientId:             00000b6c . 00000cfc
    RpcHandle:            00000000
    Tls Storage:          7ffdf02c
    PEB Address:          7ffd4000
    LastErrorValue:       0
    LastStatusValue:      c0000139
    Count Owned Locks:    0
    HardErrorMode:        0

0:000> dps 0011e000 00130000
0011e000  00000000
0011e004  00000000
0011e008  00000000
0012e72c  00130000
0012e730  0011e000
0012e734  00ee350d
0012e738  0012ea3c
0012e73c  77f299f7 ntdll!KiUserExceptionDispatcher+0xf
0012e740  0012e750
0012e744  0012e76c
0012e748  0012e750
0012e74c  0012e76c
0012e750  c0000005
0012e754  00000000
0012e758  00000000
0012e75c  77f17d89 ntdll!RtlLeaveCriticalSection+0×9
0012e760  00000002
0012e764  00000001
0012e768  00000028
0012e76c  0001003f
0012e770  00000000
0012e774  00000000
0012e778  00000000
0012e77c  00000000

0:000> .cxr 0012e76c
eax=00000020 ebx=09ca1fa0 ecx=781c1b78 edx=00000001 esi=00000020 edi=09ca1ff8
eip=77f17d89 esp=0012ea38 ebp=0012ea3c iopl=0         nv up ei pl nz na po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010202
77f17d89 834608ff        add     dword ptr [esi+8],0FFFFFFFFh ds:0023:00000028=????????

0:000> kL
  *** Stack trace for last set context - .thread/.cxr resets it
ChildEBP RetAddr 
0012ea3c 7813e5b5 ntdll!RtlLeaveCriticalSection+0x9
0012ea44 2071c9ba msvcr80!_unlock_file+0x35
WARNING: Stack unwind information not available. Following frames may be wrong.
0012ea68 2071c31e DllB!getType+0×286a
0012ee34 206bbfbc DllB!getType+0×3eb
0012ee68 206c8abb DllC+0xbfbc
0012ee98 79e71ca7 DllC!getFirstField+0×3b

0012f148 77d6f8d2 mscorwks!NDirectGenericStubReturnFromCall
0012f1ec 77d70008 user32!InternalCallWinProc+0×23
0012f240 77db51b9 user32!DispatchMessageWorker+0×322
0012f4a4 79e95feb user32!_W32ExceptionHandler+0×18
0012f4fc 79e968b0 mscorwks!MetaSig::HasRetBuffArg+0×5
0012f50c 79e9643e mscorwks!MetaSig::MetaSig+0×3a
0012f610 79e96534 mscorwks!MethodDesc::CallDescr+0xaf
0012f62c 79e96552 mscorwks!MethodDesc::CallTargetWorker+0×1f
0012f644 79eefa45 mscorwks!MethodDescCallSite::CallWithValueTypes+0×1a
0012f7a8 79eef965 mscorwks!ClassLoader::RunMain+0×223

Therefore we identified DllB and DllC components as suspicious. If we check exception chain we see that .NET runtime registered custom exception handlers:

0:000> !exchain
0012e470: mscorwks!COMPlusNestedExceptionHandler+0 (79edd6d7)
0012f13c: mscorwks!FastNExportExceptHandler+0 (7a00a2e7)

0012f1dc: user32!_except_handler4+0 (77db51ba)
0012f240: user32!_except_handler4+0 (77db51ba)
0012f46c: mscorwks!COMPlusFrameHandler+0 (79edc3bc)
0012f4c0: mscorwks!_except_handler4+0 (79f908a2)
0012f798: mscorwks!_except_handler4+0 (79f908a2)
0012fa04: mscorwks!GetManagedNameForTypeInfo+a680 (7a328d90)
0012fed4: mscorwks!GetManagedNameForTypeInfo+82c8 (7a325a3a)
0012ff20: mscorwks!_except_handler4+0 (79f908a2)
0012ff6c: mscorwks!GetManagedNameForTypeInfo+a6e (7a319ee4)
0012ffc4: ntdll!_except_handler4+0 (77ed9834)
Invalid exception stack at ffffffff

We check that GetManagedNameForTypeInfo+a6e (7a319ee4) is an exception handler indeed:

0:000> .asm no_code_bytes
Assembly options: no_code_bytes

0:000> uf 7a319ee4
78158aeb push ebp
78158aec mov ebp,esp
78158aee sub esp,8
78158af1 push ebx
78158af2 push esi
78158af3 push edi
78158af4 cld
78158af5 mov dword ptr [ebp-4],eax
78158af8 xor eax,eax
78158afa push eax
78158afb push eax
78158afc push eax
78158afd push dword ptr [ebp-4]
78158b00 push dword ptr [ebp+14h]
78158b03 push dword ptr [ebp+10h]
78158b06 push dword ptr [ebp+0Ch]
78158b09 push dword ptr [ebp+8]
78158b0c call msvcr80!__InternalCxxFrameHandler (7815897e)
78158b11 add esp,20h
78158b14 mov dword ptr [ebp-8],eax
78158b17 pop edi
78158b18 pop esi
78158b19 pop ebx
78158b1a mov eax,dword ptr [ebp-8]
78158b1d mov esp,ebp
78158b1f pop ebp
78158b20 ret

79f5f258 jmp dword ptr [mscorwks!_imp____CxxFrameHandler3 (79e711c4)]

7a319ee4 mov edx,dword ptr [esp+8]
7a319ee8 lea eax,[edx+0Ch]
7a319eeb mov ecx,dword ptr [edx-30h]
7a319eee xor ecx,eax
7a319ef0 call mscorwks!__security_check_cookie (79e72037)
7a319ef5 mov eax,offset mscorwks!_CT??_R0H+0xc14 (7a319f00)
7a319efa jmp mscorwks!__CxxFrameHandler3 (79f5f258)

- Dmitry Vostokov @ -

3 Responses to “Crash Dump Analysis Patterns (Part 90)”

  1. Marc Sherman Says:



    0012e73c 77f299f7 ntdll!KiUserExceptionDispatcher+0xf
    0012e740 0012e750
    0012e744 0012e76c

    Does this correspond to the args for the call to ntdll!RtlDispatchException?

    If so, then 0012e76c is the 2nd arg to ntdll!RtlDispatchException which is the context record?


  2. Dmitry Vostokov Says:

    Yes, it corresponds because it calls it:

    0:000> ub 77f299f7
    77f299e2 ret 0Ch
    77f299e5 lea ecx,[ecx]
    77f299e8 cld
    77f299e9 mov ecx,dword ptr [esp+4]
    77f299ed mov ebx,dword ptr [esp]
    77f299f0 push ecx
    77f299f1 push ebx
    77f299f2 call ntdll!RtlDispatchException (77f0d132)

  3. Dmitry Vostokov Says:

    The other way around, when CLR exception is enveloped by unmanaged exception is possible like in this example:

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