Crash Dump Analysis Patterns (Part 125)

Similar to Blocking Module pattern we also have Top Module pattern where the difference is in stack trace syntax only. A top module is any module we choose that is simply on top of a stack trace. Most of the time it is likely to be a non-OS vendor module. Whether the stack trace is well-formed and semantically sound or incorrect is irrelevant:

0:005> kL
ChildEBP RetAddr 
01abc4d8 6efba23d ntdll!KiFastSystemCallRet
WARNING: Stack unwind information not available. Following frames may be wrong.
01abc988 7c820833 ModuleB+0×2a23d
01abcbe4 7c8207f6 kernel32!GetVolumeNameForRoot+0×26
01abcc0c 7c82e6de kernel32!BasepGetVolumeNameForVolumeMountPoint+0×75
01abcc54 6efaf70b kernel32!GetVolumePathNameW+0×18a
01abccdc 6efbd1a6 ModuleB+0×1f70b
01abcce0 00000000 ModuleB+0×2d1a6

Here we can also check the validity of ModuleB code by backwards disassembly of 6efba23d return address (ub command) unless we have an abridged dump file (minidump) and we need to specify the image file path in WinDbg,

Why a top module is important? In various troubleshooting scenarious we can check the module timestamp (Not My Version pattern) and other useful information (lmv and !lmi WinDbg commands). If we suspect the module belonging to hooksware we can also recommend removing it or its software vendor package for testing purposes.

- Dmitry Vostokov @ + -

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