Invalid handle, stack trace collection, multiple exceptions, invalid pointer, data alignment on page boundary, dynamic memory corruption and not my version: pattern cooperation

Here we can look at one process dump with many patterns seen inside. Default WinDbg analysis command !analyze -v points to invalid handle exception perhaps at DLL initialization time during thread attach to DllA module:

0296fa68 7c90eb93 ntdll!KiRaiseUserExceptionDispatcher+0x37
0296fa7c 10001252 ntdll!KiFastSystemCallRet+0x4
WARNING: Stack unwind information not available. Following frames may be wrong.
0296faa8 771215f8 DllA!DllMain+0×202
0296fbec 100014b0 OLEAUT32!DllMain+0×2c
0296fc0c 7c9011a7 DllA!DllMain+0×460
0296fc2c 7c918f65 ntdll!LdrpCallInitRoutine+0×14
0296fca0 7c918dde ntdll!LdrpInitializeThread+0xc0
0296fd18 7c90eac7 ntdll!_LdrpInitialize+0×219
00000000 00000000 ntdll!KiUserApcDispatcher+0×7

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 7c90eb74 (ntdll!KiRaiseUserExceptionDispatcher+0x00000037)
   ExceptionCode: c0000008 (Invalid handle)
  ExceptionFlags: 00000000
NumberParameters: 0
Thread tried to close a handle that was invalid or illegal to close

We may stop here after applying lmv command to DllA and recommending to upgrade / remove that component. But let’s look a bit deeper inside that crash dump. If we list all thread stacks (stack trace collection) we would see another thread with unhandled exception processing stack:

0:000> ~*kL

.  0  Id: a1c.e78 Suspend: 1 Teb: 7ffdf000 Unfrozen
ChildEBP RetAddr 
0012da34 7c90e9ab ntdll!KiFastSystemCallRet
0012da38 7c86372c ntdll!ZwWaitForMultipleObjects+0xc
0012e1a8 77c32f0f kernel32!UnhandledExceptionFilter+0×8e4
0012e1c4 0041808b msvcrt!_XcptFilter+0×161

0012ffc0 7c816fd7 Application!WinMainCRTStartup+0×14f
0012fff0 00000000 kernel32!BaseProcessStart+0×23

   1  Id: a1c.2ec Suspend: 1 Teb: 7ffdc000 Unfrozen
ChildEBP RetAddr 
02faff84 7c90e9ab ntdll!KiFastSystemCallRet
02faff88 5b890f8c ntdll!ZwWaitForMultipleObjects+0xc
02faffb4 7c80b683 NETAPI32!NetbiosWaiter+0x73
02faffec 00000000 kernel32!BaseThreadStart+0x37

   2  Id: a1c.c14 Suspend: 1 Teb: 7ffdb000 Unfrozen
ChildEBP RetAddr 
036afe1c 7c90e9ab ntdll!KiFastSystemCallRet
036afe20 7c8094e2 ntdll!ZwWaitForMultipleObjects+0xc
036afebc 7e4195f9 kernel32!WaitForMultipleObjectsEx+0x12c
036aff18 7e4196a8 USER32!RealMsgWaitForMultipleObjectsEx+0x13e
036aff34 00450d91 USER32!MsgWaitForMultipleObjects+0x1f
036aff80 77c3a3b0 Application!ThreadProc+0x61
036affb4 7c80b683 msvcrt!_endthreadex+0xa9
036affec 00000000 kernel32!BaseThreadStart+0x37

   3  Id: a1c.15c Suspend: 1 Teb: 7ffda000 Unfrozen
ChildEBP RetAddr 
0417ff78 7c90e31b ntdll!KiFastSystemCallRet
0417ff7c 71a5d320 ntdll!ZwRemoveIoCompletion+0xc
0417ffb4 7c80b683 mswsock!SockAsyncThread+0x5a
0417ffec 00000000 kernel32!BaseThreadStart+0x37

#  4  Id: a1c.96c Suspend: 1 Teb: 7ffde000 Unfrozen
ChildEBP RetAddr 
0296fa68 7c90eb93 ntdll!KiRaiseUserExceptionDispatcher+0x37
0296fa7c 10001252 ntdll!KiFastSystemCallRet+0x4
WARNING: Stack unwind information not available. Following frames may be wrong.
0296faa8 771215f8 DllA!DllMain+0x202
0296fbec 100014b0 OLEAUT32!DllMain+0x2c
0296fc0c 7c9011a7 DllA!DllMain+0x460
0296fc2c 7c918f65 ntdll!LdrpCallInitRoutine+0x14
0296fca0 7c918dde ntdll!LdrpInitializeThread+0xc0
0296fd18 7c90eac7 ntdll!_LdrpInitialize+0x219
00000000 00000000 ntdll!KiUserApcDispatcher+0x7

Seems we have multiple exceptions here. Let’s extract thread 0 exception:

0:000> kv
ChildEBP RetAddr  Args to Child             
0012da34 7c90e9ab 7c86372c 00000002 0012dbac ntdll!KiFastSystemCallRet
0012da38 7c86372c 00000002 0012dbac 00000001 ntdll!ZwWaitForMultipleObjects+0xc
0012e1a8 77c32f0f 0012e1f0 00000000 00000000 kernel32!UnhandledExceptionFilter+0×8e4
0012e1c4 0041808b 00000000 0012e1f0 77c35cf5 msvcrt!_XcptFilter+0×161
0012ffc0 7c816fd7 00160000 001ae3c6 7ffdd000 Application!WinMainCRTStartup+0×14f
0012fff0 00000000 00417f3c 00000000 78746341 kernel32!BaseProcessStart+0×23

0:000> .exptr 0012e1f0

----- Exception record at 0012e2e4:
ExceptionAddress: 77c47fd4 (msvcrt!wcslen+0x00000008)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 04649000
Attempt to read from address 04649000

----- Context record at 0012e300:
eax=04649000 ebx=00000000 ecx=0464006c edx=04648fb4 esi=04648fd0 edi=00000000
eip=77c47fd4 esp=0012e5cc ebp=0012e5cc iopl=0  nv up ei pl nz na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000  efl=00010206
77c47fd4 668b08          mov     cx,word ptr [eax]        ds:0023:04649000=????

0:000> kv
  *** Stack trace for last set context - .thread/.cxr resets it
ChildEBP RetAddr  Args to Child             
0012e5cc 7301561a 04648fd0 00000030 00000018 msvcrt!wcslen+0×8
0012e5f0 73016c32 04648fd0 04afefe8 00000000 DllB!UnicodeToAnsiString+0×105

We see invalid pointer access violation while calculating string length. If we look at invalid address we see that UNICODE string crosses page boundary into a reserved page:

0:000> dd 04648fd0
04648fd0  0060004d 00620066 00680072 0020006f
04648fe0  00200034 00630022 007100ea 00710060
04648ff0  00200073 0060006e 0076006f 006d0066

04649000  ???????? ???????? ???????? ????????
04649010  ???????? ???????? ???????? ????????
04649020  ???????? ???????? ???????? ????????
04649030  ???????? ???????? ???????? ????????
04649040  ???????? ???????? ???????? ????????

0:000> !address 04648fd0
    04648000 : 04648000 - 00001000
                    Type     00020000 MEM_PRIVATE
                    Protect  00000004 PAGE_READWRITE
                    State    00001000 MEM_COMMIT
                    Usage    RegionUsageIsVAD

0:000> !address 04649000
    045e0000 : 04649000 - 00001000
                    Type     00040000 MEM_MAPPED
                    State    00002000 MEM_RESERVE
                    Usage    RegionUsageIsVAD

And we also notice full page heap enabled to catch possible heap corruption (dynamic memory corruption):

0:000> !gflag
Current NtGlobalFlag contents: 0x02000000
    hpa - Place heap allocations at ends of pages

This explains why we see invalid handle exception which is normally ignored by runtime unless we enable Application Verifier. Looking at DllB version data we see that it is the old component that needs to be upgraded.

- Dmitry Vostokov @ -

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