Crash Dump Analysis Patterns (Part 105)
Thursday, August 5th, 2010The one obvious pattern that is shown in many case studies on this blog is Exception Stack Trace (or Exception Thread). This is a stack trace that has exception processing functions, for example:
9 Id: 1df4.a08 Suspend: -1 Teb: 7fff4000 Unfrozen
ChildEBP RetAddr
1022f5a8 7c90df4a ntdll!KiFastSystemCallRet
1022f5ac 7c8648a2 ntdll!ZwWaitForMultipleObjects+0xc
1022f900 7c83ab50 kernel32!UnhandledExceptionFilter+0×8b9
1022f908 7c839b39 kernel32!BaseThreadStart+0×4d
1022f930 7c9032a8 kernel32!_except_handler3+0×61
1022f954 7c90327a ntdll!ExecuteHandler2+0×26
1022fa04 7c90e48a ntdll!ExecuteHandler+0×24
1022fa04 7c812afb ntdll!KiUserExceptionDispatcher+0xe
1022fd5c 0b82e680 kernel32!RaiseException+0×53
WARNING: Stack unwind information not available. Following frames may be wrong.
1022fd94 0b82d2f2 DllA+0×21e640
1022fde8 7753004f DllA+0×21d4f2
1022fdfc 7753032f ole32!CClassCache::CDllPathEntry::CanUnload_rl+0×3b
1022ff3c 7753028b ole32!CClassCache::FreeUnused+0×70
1022ff4c 775300b5 ole32!CoFreeUnusedLibrariesEx+0×36
1022ff58 77596af5 ole32!CoFreeUnusedLibraries+0×9
1022ff6c 77566ff9 ole32!CDllHost::MTAWorkerLoop+0×25
1022ff8c 7752687c ole32!CDllHost::WorkerThread+0xc1
1022ff94 774fe3ee ole32!DLLHostThreadEntry+0xd
1022ffa8 774fe456 ole32!CRpcThread::WorkerLoop+0×1e
1022ffb4 7c80b729 ole32!CRpcThreadCache::RpcWorkerThreadEntry+0×1b
1022ffec 00000000 kernel32!BaseThreadStart+0×37
Such exceptions can be detected by the default analysis command (for example, !analyze -v WinDbg command) or by inspecting a stack trace collection. However if we didn’t see any exception thread it doesn’t mean that no exception had occurred. There could be hidden exceptions on raw stack data.
In our case we can get the exception information by looking at parameters to in unhandled exception filter:
0:009> kv 3
ChildEBP RetAddr Args to Child
1022f5a8 7c90df4a 7c8648a2 00000002 1022f730 ntdll!KiFastSystemCallRet
1022f5ac 7c8648a2 00000002 1022f730 00000001 ntdll!ZwWaitForMultipleObjects+0xc
1022f900 7c83ab50 1022f928 7c839b39 1022f930 kernel32!UnhandledExceptionFilter+0×8b9
0:009> .exptr 1022f928
----- Exception record at 1022fa1c:
ExceptionAddress: 7c812afb (kernel32!RaiseException+0x00000053)
ExceptionCode: e06d7363 (C++ EH exception)
ExceptionFlags: 00000001
NumberParameters: 3
Parameter[0]: 19930520
Parameter[1]: 1022fda4
Parameter[2]: 0b985074
pExceptionObject: 1022fda4
_s_ThrowInfo : 0b985074
----- Context record at 1022fa3c:
eax=1022fd0c ebx=00000001 ecx=00000000 edx=1022fda4 esi=1022fd94 edi=77606068
eip=7c812afb esp=1022fd08 ebp=1022fd5c iopl=0 nv up ei pl nz na pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00000206
kernel32!RaiseException+0x53:
7c812afb 5e pop esi
- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -