Crash Dump Analysis Patterns (Part 39)

As mentioned in Early Crash Dump pattern saving crash dumps on first-chance exceptions helps to diagnose components that might have caused corruption and later crashes, hangs or CPU spikes by ignoring abnormal exceptions like access violation. In such cases we need to know whether an application installs its own Custom Exception Handler or several of them. If it uses only default handlers provided by runtime or windows subsystem then most likely a first-chance access violation exception will result in a last-chance exception and a postmortem dump. To check a chain of exception handlers we can use WinDbg !exchain extention command. For example:

0:000> !exchain
0017f9d8: TestDefaultDebugger!AfxWinMain+3f5 (00420aa9)
0017fa60: TestDefaultDebugger!AfxWinMain+34c (00420a00)
0017fb20: user32!_except_handler4+0 (770780eb)
0017fcc0: user32!_except_handler4+0 (770780eb)
0017fd24: user32!_except_handler4+0 (770780eb)
0017fe40: TestDefaultDebugger!AfxWinMain+16e (00420822)
0017feec: TestDefaultDebugger!AfxWinMain+797 (00420e4b)
0017ff90: TestDefaultDebugger!_except_handler4+0 (00410e00)
0017ffdc: ntdll!_except_handler4+0 (77961c78)

We see that TestDefaultDebugger doesn’t have its own exception handlers except ones provided by MFC and C/C++ runtime libraries which were linked statically. Here is another example. It was reported that a 3rd-party application was hanging and spiking CPU (Spiking Thread pattern) so a user dump was saved using command line userdump.exe:

0:000> vertarget
Windows Server 2003 Version 3790 (Service Pack 2) MP (4 procs) Free x86 compatible
Product: Server, suite: TerminalServer
kernel32.dll version: 5.2.3790.4062 (srv03_sp2_gdr.070417-0203)
Debug session time: Thu Nov 22 12:45:59.000 2007 (GMT+0)
System Uptime: 0 days 10:43:07.667
Process Uptime: 0 days 4:51:32.000 
Kernel time: 0 days 0:08:04.000 
User time: 0 days 0:23:09.000

0:000> !runaway 3 
User Mode Time 
Thread Time  
0:1c1c      0 days 0:08:04.218  
1:2e04      0 days 0:00:00.015
Kernel Mode Time 
Thread Time  
0:1c1c      0 days 0:23:09.156  
1:2e04      0 days 0:00:00.031

0:000> kL
ChildEBP RetAddr 
0012fb80 7739bf53 ntdll!KiFastSystemCallRet
0012fbb4 05ca73b0 user32!NtUserWaitMessage+0xc
WARNING: Stack unwind information not available. Following frames may be wrong.
0012fd20 05c8be3f 3rdPartyDLL+0x573b0
0012fd50 05c9e9ea 3rdPartyDLL+0x3be3f
0012fd68 7739b6e3 3rdPartyDLL+0x4e9ea
0012fd94 7739b874 user32!InternalCallWinProc+0x28
0012fe0c 7739c8b8 user32!UserCallWinProcCheckWow+0x151
0012fe68 7739c9c6 user32!DispatchClientMessage+0xd9
0012fe90 7c828536 user32!__fnDWORD+0x24
0012febc 7739d1ec ntdll!KiUserCallbackDispatcher+0x2e
0012fef8 7738cee9 user32!NtUserMessageCall+0xc
0012ff18 0050aea9 user32!SendMessageA+0x7f
0012ff70 00452ae4 3rdPartyApp+0x10aea9
0012ffac 00511941 3rdPartyApp+0x52ae4
0012ffc0 77e6f23b 3rdPartyApp+0x111941
0012fff0 00000000 kernel32!BaseProcessStart+0x23

Exception chain showed custom exception handlers:

0:000> !exchain
0012fb8c: 3rdPartyDLL+57acb (05ca7acb)
0012fd28: 3rdPartyDLL+3be57 (05c8be57)
0012fd34: 3rdPartyDLL+3be68 (05c8be68)

0012fdfc: user32!_except_handler3+0 (773aaf18)
  CRT scope  0, func:   user32!UserCallWinProcCheckWow+156 (773ba9ad)
0012fe58: user32!_except_handler3+0 (773aaf18)
0012fea0: ntdll!KiUserCallbackExceptionHandler+0 (7c8284e8)
0012ff3c: 3rdPartyApp+53310 (00453310)
0012ff48: 3rdPartyApp+5334b (0045334b)
0012ff9c: 3rdPartyApp+52d06 (00452d06)
0012ffb4: 3rdPartyApp+38d4 (004038d4)

0012ffe0: kernel32!_except_handler3+0 (77e61a60)
  CRT scope  0, filter: kernel32!BaseProcessStart+29 (77e76a10)
                func:   kernel32!BaseProcessStart+3a (77e81469)

The customer then enabled MS Exception Monitor and selected only Access violation exception code (c0000005) to avoid False Positive Dumps. During application execution various 1st-chance exception crash dumps were saved pointing to numerous access violations including function calls into unloaded modules, for example:

0:000> kL 100
ChildEBP RetAddr 
WARNING: Frame IP not in any known module. Following frames may be wrong.
0012f910 7739b6e3 <Unloaded_Another3rdParty.dll>+0x4ce58
0012f93c 7739b874 user32!InternalCallWinProc+0x28
0012f9b4 7739c8b8 user32!UserCallWinProcCheckWow+0x151
0012fa10 7739c9c6 user32!DispatchClientMessage+0xd9
0012fa38 7c828536 user32!__fnDWORD+0x24
0012fa64 7739d1ec ntdll!KiUserCallbackDispatcher+0x2e
0012faa0 7738cee9 user32!NtUserMessageCall+0xc
0012fac0 0a0f2e01 user32!SendMessageA+0x7f
0012fae4 0a0f2ac7 3rdPartyDLL+0x52e01
0012fb60 7c81a352 3rdPartyDLL+0x52ac7
0012fb80 7c839dee ntdll!LdrpCallInitRoutine+0x14
0012fc94 77e6b1bb ntdll!LdrUnloadDll+0x41a
0012fca8 0050c9c1 kernel32!FreeLibrary+0x41
0012fdf4 004374af 3rdPartyApp+0x10c9c1
0012fe24 0044a076 3rdPartyApp+0x374af
0012fe3c 7739b6e3 3rdPartyApp+0x4a076
0012fe68 7739b874 user32!InternalCallWinProc+0x28
0012fee0 7739ba92 user32!UserCallWinProcCheckWow+0x151
0012ff48 773a16e5 user32!DispatchMessageWorker+0x327
0012ff58 00452aa0 user32!DispatchMessageA+0xf
0012ffac 00511941 3rdPartyApp+0x52aa0
0012ffc0 77e6f23b 3rdPartyApp+0x111941
0012fff0 00000000 kernel32!BaseProcessStart+0x23

- Dmitry Vostokov @ -

3 Responses to “Crash Dump Analysis Patterns (Part 39)”

  1. Crash Dump Analysis » Blog Archive » Heap and early crash dump: pattern cooperation Says:

    […] was suspected that access violation errors were handled by application exception handlers (Custom Exception Handler pattern) and it was recommended to catch first-chance exception crash dumps (Early Crash […]

  2. Dmitry Vostokov Says:

    I was asked where to get MS Exception Monitor. Here is the answer:

    If you download userdump package and install it (there is setup.exe) you get exception monitor:

  3. Crash Dump Analysis » Blog Archive » Icons for Memory Dump Analysis Patterns (Part 64) Says:

    […] Sponsored link: Memory Dump Analysis Services Today we introduce an icon for Custom Exception Handler pattern: […]

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