Crash Dump Analysis

Today we introduce an icon for Lateral Damage pattern:

B/W

Color

With fix-privet,
Dr. DebugLove

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Today we introduce an icon for False Positive Dump pattern:

B/W

Color

With fix-privet,
Dr. DebugLove

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Today we introduce an icon for Dynamic Memory Corruption (kernel pool) pattern:

B/W

Color

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Today we introduce an icon for Dynamic Memory Corruption (process heap) pattern:

B/W

Color

Another alternative I considered to use is a chain metaphor but decided that it is more appropriate for linked lists.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Today we introduce an icon for Multiple Exceptions (kernel mode) pattern:

B/W

Color

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

I borrowed a pattern icon idea from the book I’m reading now: Algorithms in a Nutshell

From now on, every memory dump analysis pattern (and later trace analysis patterns) will have platform-independent pictorial representation. Today we introduce an icon for Multiple Exceptions (user mode) pattern:

B/W

Color

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

This post was motivated during my work on a memory dump differing tool called DumpLogic that can do logical and arithmetic operations between memory snapshots, for example, take a difference between them for further visualization. This tool is forthcoming next week and it resulted in another simple tool called DumpFilter. The latter allows to filter certain unsigned integer (DWORD) values from a memory dump (or any binary file) by replacing them with 0xFFFFFFFF and all other values with 0×00000000. The resultant binary file can be visualized by any data visualization package or transformed to a bitmap file using Dump2Picture to see distribution of filtered values.

As a filtering example I used TestDefaultDebugger64 to generate a process user memory dump. It was converted to a BMP file by Dump2Picture: 

Then I filtered only AV exception code 0xc0000005:

C:\>DumpFilter tdd64.dmp tdd64.bin <dwords.txt

dwords.txt just contained one line 

c0000005

It is possible to filter many values. Just put more lines to dwords.txt file. tdd64.bin was converted to tdd64.bmp by Dump2Picture:

C:\>Dump2Picture tdd64.bin tdd64.bmp

Because the image had only black and while RGBA colors I saved it as a B/W bitmap (click to enlarge, it is a 3236×3236 1.3Mb bitmap):

Every EV exception code is a white dot there but it is difficult to see them unless magnified. So I enlarged them manually on the following map:

I put them on the original image too. We can see that exception processing spans many areas:

The tool and the sample dwords.txt file (for c0000005 and 80000003) can be downloaded from this location:

Download DumpFilter

Another example: Night Sky memory space art image is just a fragment after filtering all 1 values from another process memory dump.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Here is a synthetic case study to show various wait chain patterns. The complete memory dump from a frozen system is inconsistent, saved by LiveKd. Stack trace collection shows many threads waiting for LPC replies:

THREAD 87432520  Cid 0b10.0dd8  Teb: 7ff83000 Win32Thread: 00000000 WAIT: (Unknown) UserMode Non-Alertable
    8743270c  Semaphore Limit 0x1
Waiting for reply to LPC MessageId 007ade85:
Current LPC port d676e560
Not impersonating
DeviceMap                 d6f05be8
Owning Process            87581c78       Image:         ProcessA.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      4093415        Ticks: 659565 (0:02:51:45.703)
Context Switch Count      111255            
UserTime                  00:00:27.781
KernelTime                00:00:02.015
Win32 Start Address MSVCR71!_threadstartex (0×7c3494f6)
Start Address kernel32!BaseThreadStartThunk (0×77e617ec)
Stack Init b6439000 Current b6438c08 Base b6439000 Limit b6436000 Call 0
Priority 8 BasePriority 8 PriorityDecrement 0
Kernel stack not resident.
ChildEBP RetAddr 
b6438c10 00000000 0×0

Checking MessageId by using !lpc command gives us the following LPC server thread that is waiting for a mutant owned by thread 866d63e8 (this is equivalent that thread 85b209d0 is waiting for thread 866d63e8):

THREAD 85b209d0  Cid 1524.2770  Teb: 7ff78000 Win32Thread: 00000000 WAIT: (Unknown) UserMode Non-Alertable
    85e9ba00  Mutant - owning thread 866d63e8
Not impersonating
DeviceMap                 d64008d8
Owning Process            87200880       Image:         ProcessB.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      4093415        Ticks: 659565 (0:02:51:45.703)
Context Switch Count      28            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address 0×007ade85
LPC Server thread working on message Id 7ade85
Start Address kernel32!BaseThreadStartThunk (0×77e617ec)
Stack Init b42e5000 Current b42e4c60 Base b42e5000 Limit b42e2000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0
Kernel stack not resident.
ChildEBP RetAddr 
b42e4c68 00000000 0xa000a02

Thread 866d63e8 is waiting for a process 86b33b30:

THREAD 866d63e8  Cid 1524.3984  Teb: 7ff6e000 Win32Thread: 00000000 WAIT: (Unknown) UserMode Non-Alertable
    86b33b30  ProcessObject
    866d6460  NotificationTimer
Not impersonating
DeviceMap                 d64008d8
Owning Process            87200880       Image:         ProcessB.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      4755080     
Context Switch Count      4767            
UserTime                  00:00:00.015
KernelTime                00:00:00.000
Win32 Start Address 0×007a5051
LPC Server thread working on message Id 7a5051
Start Address kernel32!BaseThreadStartThunk (0×77e617ec)
Stack Init ab459000 Current ab458c60 Base ab459000 Limit ab456000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0
ChildEBP RetAddr 
ab458c78 8083d5b1 nt!KiSwapContext+0×26
ab458ca4 8083df9e nt!KiSwapThread+0×2e5
ab458cec 8092ae67 nt!KeWaitForSingleObject+0×346
ab458d50 80833bef nt!NtWaitForSingleObject+0×9a
ab458d50 7c82860c nt!KiFastCallEntry+0xfc (TrapFrame @ ab458d64)
0499fbec 7c827d29 ntdll!KiFastSystemCallRet
0499fbf0 76548721 ntdll!ZwWaitForSingleObject+0xc
0499fc0c 7654aa54 ProcessB!WaitForProcess+0×4a
[…]
0499ffec 00000000 kernel32!BaseThreadStart+0×34

We find the following thread in the process 86b33b30 (there is only one thread left where we expect many of them in ProcessC):

THREAD 85a6fdb0  Cid 5c0c.26f4  Teb: 7ffdf000 Win32Thread: b9b778a0 WAIT: (Unknown) KernelMode Non-Alertable
    86686030  SynchronizationEvent
    85a6fe28  NotificationTimer
Not impersonating
DeviceMap                 d6767248
Owning Process            86b33b30       Image:         ProcessC.EXE
Attached Process          N/A            Image:         N/A
Wait Start TickCount      4755681     
Context Switch Count      77668                 LargeStack
UserTime                  00:00:00.437
KernelTime                00:00:04.421
*** ERROR: Module load completed but symbols could not be loaded for ProcessC.EXE
Win32 Start Address 0×300010cc
Start Address kernel32!BaseProcessStartThunk (0×77e617f8)
Stack Init 9ad92000 Current 9ad91a40 Base 9ad92000 Limit 9ad8d000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0
ChildEBP RetAddr 
9ad91a58 8083d5b1 nt!KiSwapContext+0×26
9ad91a84 8083df9e nt!KiSwapThread+0×2e5
9ad91acc 8081e05b nt!KeWaitForSingleObject+0×346
9ad91b08 8082e012 nt!ExpWaitForResource+0xd5
9ad91b28 b6a9c1ee nt!ExAcquireResourceExclusiveLite+0×8d
WARNING: Stack unwind information not available. Following frames may be wrong.
9ad91b38 b6ab09d3 DriverA+0×21ee
[…]
9ad91c3c 80840153 DriverA+0×1ed6
9ad91c50 8092b51f nt!IofCallDriver+0×45
9ad91c64 8092b454 nt!IopSynchronousServiceTail+0×10b
9ad91d00 8092b574 nt!IopXxxControlFile+0×60f
9ad91d34 80833bef nt!NtDeviceIoControlFile+0×2a
9ad91d34 7c82860c nt!KiFastCallEntry+0xfc (TrapFrame @ 9ad91d64)
0012d4e0 00000000 ntdll!KiFastSystemCallRet

It is blocked by DriverA waiting for an executive resource. Fortunately !locks command works for this inconsistent dump and we finally reach thread 86ba5638:

0: kd> !locks

Resource @ 0x85610d30    Exclusively owned
    Contention Count = 4
    NumberOfExclusiveWaiters = 1
     Threads: 86ba5638-01<*>
     Threads Waiting On Exclusive Access:
              85a6fdb0

This thread belongs to another instance of ProcessC.exe (different process 8690dd88):

0: kd> !thread 86ba5638 1f
THREAD 86ba5638  Cid 186c.1574  Teb: 7ffdf000 Win32Thread: b9a28a70 WAIT: (Unknown) KernelMode Non-Alertable
    8944e3d4  SynchronizationEvent
Not impersonating
DeviceMap                 d6767248
Owning Process            8690dd88       Image:         ProcessC.EXE
Attached Process          N/A            Image:         N/A
Wait Start TickCount      4074148        Ticks: 678832 (0:02:56:46.750)
Context Switch Count      95896                 LargeStack
UserTime                  00:00:00.593
KernelTime                00:00:05.343
*** ERROR: Module load completed but symbols could not be loaded for ProcessC.EXE
Win32 Start Address 0×300010cc
Start Address kernel32!BaseProcessStartThunk (0×77e617f8)
Stack Init 99ef2000 Current 99ef19c0 Base 99ef2000 Limit 99eec000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0
ChildEBP RetAddr 
99ef19d8 8083d5b1 nt!KiSwapContext+0×26
99ef1a04 8083df9e nt!KiSwapThread+0×2e5
99ef1a4c 80853f3f nt!KeWaitForSingleObject+0×346
99ef1a64 8081d45f nt!KiAcquireFastMutex+0×13
99ef1a70 b6a9c70d nt!ExAcquireFastMutex+0×20
WARNING: Stack unwind information not available. Following frames may be wrong.
99ef1a7c b6aaf22a DriverA+0×270d
[…]
99ef1c3c 80840153 DriverA+0×1ed6
99ef1c50 8092b51f nt!IofCallDriver+0×45
99ef1c64 8092b454 nt!IopSynchronousServiceTail+0×10b
99ef1d00 8092b574 nt!IopXxxControlFile+0×60f
99ef1d34 80833bef nt!NtDeviceIoControlFile+0×2a
99ef1d34 7c82860c nt!KiFastCallEntry+0xfc (TrapFrame @ 99ef1d64)
0012db08 00000000 ntdll!KiFastSystemCallRet

We see this thread is also blocked by DriverA. We also check thread waiting times. All threads involved in wait chains have their Ticks value less than 86ba5638. This means that thread 86ba5638 was blocked earlier. We contact DriverA vendor for any possible updates.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

For certain stack traces we should always be aware of Coincidental Frames similar to Coincidental Symbolic Information pattern for raw stack data. Such frames can lead to a wrong analysis conclusion. Consider this stack trace fragment from a kernel memory dump:

0: kd> kL 100
ChildEBP RetAddr
9c5b6550 8082d9a4 nt!KeBugCheckEx+0×1b
9c5b6914 8088befa nt!KiDispatchException+0×3a2
9c5b697c 8088beaent!CommonDispatchException+0×4a
9c5b699c 80a6056dnt!KiExceptionExit+0×186
9c5b69a0 80893ae2hal!KeReleaseQueuedSpinLock+0×2d
9c5b6a08 b20c3de5 nt!MiFreePoolPages+0×7dc
WARNING: Stack unwind information not available. Following frames may be wrong.
9c5b6a48 b20c4107 DeriverA+0×17de5
[…]

The frame with MiFreePoolPages symbol might suggest some sort of a pool corruption. We can even double check return addresses and see the valid common sense assembly language code:

0: kd> ub 8088beae
nt!KiExceptionExit+0×167:
8088be8f 33c9            xor     ecx,ecx
8088be91 e81a000000      call    nt!CommonDispatchException (8088beb0)
8088be96 33d2            xor     edx,edx
8088be98 b901000000      mov     ecx,1
8088be9d e80e000000      call    nt!CommonDispatchException (8088beb0)
8088bea2 33d2            xor     edx,edx
8088bea4 b902000000      mov     ecx,2
8088bea9 e802000000      call    nt!CommonDispatchException (8088beb0)

0: kd> ub 80a6056d
hal!KeReleaseQueuedSpinLock+0×1b:
80a6055b 7511            jne     hal!KeReleaseQueuedSpinLock+0×2e (80a6056e)
80a6055d 50              push    eax
80a6055e f00fb119        lock cmpxchg dword ptr [ecx],ebx
80a60562 58              pop     eax
80a60563 7512            jne     hal!KeReleaseQueuedSpinLock+0×37 (80a60577)
80a60565 5b              pop     ebx
80a60566 8aca            mov     cl,dl
80a60568 e8871e0000      call    hal!KfLowerIrql (80a623f4)

0: kd> ub 80893ae2
nt!MiFreePoolPages+0×7c3:
80893ac9 761c            jbe     nt!MiFreePoolPages+0×7e1 (80893ae7)
80893acb ff75f8          push    dword ptr [ebp-8]
80893ace ff7508          push    dword ptr [ebp+8]
80893ad1 e87ea1fcff      call    nt!MiFreeNonPagedPool (8085dc54)
80893ad6 8a55ff          mov     dl,byte ptr [ebp-1]
80893ad9 6a0f            push    0Fh
80893adb 59              pop     ecx
80893adc ff1524118080    call    dword ptr [nt!_imp_KeReleaseQueuedSpinLock (80801124)]

0: kd> ub b20c3de5
DriverA+0×17dcf:
b20c3dcf 51              push    ecx
b20c3dd0 ff5010          call    dword ptr [eax+10h]
b20c3dd3 eb10            jmp     DriverA+0×17de5 (b20c3de5)
b20c3dd5 8b5508          mov     edx,dword ptr [ebp+8]
b20c3dd8 52              push    edx
b20c3dd9 8d86a0000000    lea     eax,[esi+0A0h]
b20c3ddf 50              push    eax
b20c3de0 e8ebf1ffff      call    DriverA+0×16fd0 (b20c2fd0)

However, if we try to reconstruct the stack trace manually we would naturally skip these 3 frames (shown in magenta):

9c5b6550 8082d9a4 nt!KeBugCheckEx+0x1b
9c5b6914 8088befa nt!KiDispatchException+0x3a2
9c5b697c 8088beae nt!CommonDispatchException+0x4a
9c5b699c 80a6056d nt!KiExceptionExit+0×186
9c5b69a0 80893ae2 hal!KeReleaseQueuedSpinLock+0×2d
9c5b6a08 b20c3de5 nt!MiFreePoolPages+0×7dc
9c5b6a48 b20c4107 DeriverA+0×17de5
[…]

0: kd> !thread
THREAD 8f277020  Cid 081c.7298  Teb: 7ff11000 Win32Thread: 00000000 RUNNING on processor 0
IRP List:
    8e234b60: (0006,0094) Flags: 00000000  Mdl: 00000000
Not impersonating
DeviceMap                 e1002880
Owning Process            8fc78b80       Image:         ProcessA.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      49046879       Ticks: 0
Context Switch Count      10            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address DllA!ThreadA (0x7654dc90)
Start Address kernel32!BaseThreadStartThunk (0x77e617dc)
Stack Init 9c5b7000 Current 9c5b6c50 Base 9c5b7000 Limit 9c5b4000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0
ChildEBP RetAddr  Args to Child             
[…]

0: kd> dds 9c5b4000 9c5b7000
9c5b4000  00000000
9c5b4004  00000000
9c5b4008  00000000
[...]
9c5b6290  ffdff13c
9c5b6294  9c5b6550
9c5b6298  80827e01 nt!KeBugCheckEx+0×1b
9c5b629c  00000008
9c5b62a0  00000286
[…]
9c5b654c  00000000
9c5b6550  9c5b6914
9c5b6554  8082d9a4 nt!KiDispatchException+0×3a2
9c5b6558  0000008e
9c5b655c  c0000005
[…]
9c5b6910  ffffffff
9c5b6914  9c5b6984
9c5b6918  8088befa nt!CommonDispatchException+0×4a
9c5b691c  9c5b6930
9c5b6920  00000000
[…]
9c5b6980  8088beae nt!KiExceptionExit+0×186
9c5b6984  9c5b6a08
9c5b6988  b20c3032 DriverA+0×17032
9c5b698c  badb0d00
9c5b6990  00000006
9c5b6994  8dc11cec
9c5b6998  808b6900 nt!KiTimerTableLock+0×3c0
9c5b699c  9c5b69d4
9c5b69a0  80a6056d hal!KeReleaseQueuedSpinLock+0×2d
9c5b69a4  80893ae2 nt!MiFreePoolPages+0×7dc
9c5b69a8  808b0b40 nt!NonPagedPoolDescriptor
9c5b69ac  03151fd0
9c5b69b0  00000000
9c5b69b4  00000000
[…]
9c5b6a04  8f47123b
9c5b6a08  9c5b6a48
9c5b6a0c  b20c3de5 DriverA+0×17de5
9c5b6a10  8e3640a0
9c5b6a14  8f4710d0
[…]
9c5b6a44  00000000
9c5b6a48  9c5b6a80
9c5b6a4c  b20c4107 DriverA+0×18107
9c5b6a50  8f4710d0
9c5b6a54  9c5b6a6c
[…]

If we try to find a pointer to the exception record we get this crash address:

0: kd> .exr 9c5b6930
ExceptionAddress: b20c3032 (DriverA+0×00017032)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 00000157
Attempt to read from address 00000157

If we disassemble it we see an inlined string or memory copy, perhaps wcscpy function:

0: kd> u b20c3032
DriverA+0×17032:
b20c3032 f3a5            rep movs dword ptr es:[edi],dword ptr [esi]
b20c3034 8bcb            mov     ecx,ebx
b20c3036 83e103          and     ecx,3
b20c3039 f3a4            rep movs byte ptr es:[edi],byte ptr [esi]
b20c303b 8b750c          mov     esi,dword ptr [ebp+0Ch]
b20c303e 0fb7ca          movzx   ecx,dx
b20c3041 894e14          mov     dword ptr [esi+14h],ecx
b20c3044 8b700c          mov     esi,dword ptr [eax+0Ch]

So the problem happened in DriverA code, not in MiFreePoolPages or KeReleaseQueuedSpinLock.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Here we show an example of a wait chain involving process objects. This Wait Chain pattern variation is similar to threads waiting for thread objects. When looking at stack trace collection from a complete memory dump file we see several threads in a set of processes are blocked in ALPC wait chain:

THREAD fffffa80110b8700  Cid 12f8.1328  Teb: 000000007ef9a000 Win32Thread: 0000000000000000 WAIT: (WrLpcReply) UserMode Non-Alertable
    fffffa80110b8a90  Semaphore Limit 0x1
Waiting for reply to ALPC Message fffff8801c7096e0 : queued at port fffffa8010c9d9a0 : owned by process fffffa80109c8c10
Not impersonating
DeviceMap                 fffff880097ce5e0
Owning Process            fffffa80110ad510       Image:         ProcessA.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      14004580       Ticks: 62149 (0:00:16:09.530)
Context Switch Count      25100            
UserTime                  00:00:00.421
KernelTime                00:00:00.218
Win32 Start Address 0×0000000074ca29e1
Stack Init fffffa6003bc4db0 Current fffffa6003bc4670
Base fffffa6003bc5000 Limit fffffa6003bbf000 Call 0
Priority 8 BasePriority 8 PriorityDecrement 0 IoPriority 2 PagePriority 5
Child-SP          RetAddr           Call Site
fffffa60`03bc46b0 fffff800`01cba0fa nt!KiSwapContext+0×7f
fffffa60`03bc47f0 fffff800`01caedab nt!KiSwapThread+0×13a
fffffa60`03bc4860 fffff800`01ce4e72 nt!KeWaitForSingleObject+0×2cb
fffffa60`03bc48f0 fffff800`01f32f34 nt!AlpcpSignalAndWait+0×92
fffffa60`03bc4980 fffff800`01f2f9c6 nt!AlpcpReceiveSynchronousReply+0×44
fffffa60`03bc49e0 fffff800`01f1f52f nt!AlpcpProcessSynchronousRequest+0×24f
fffffa60`03bc4b00 fffff800`01cb7973 nt!NtAlpcSendWaitReceivePort+0×19f
fffffa60`03bc4bb0 00000000`7713756a nt!KiSystemServiceCopyEnd+0×13 (TrapFrame @ fffffa60`03bc4c20)
00000000`016ee5b8 00000000`74f9993f ntdll!ZwAlpcSendWaitReceivePort+0xa
00000000`016ee5c0 00000000`74f8a996 wow64!whNtAlpcSendWaitReceivePort+0×5f
00000000`016ee610 00000000`75183688 wow64!Wow64SystemServiceEx+0xca
00000000`016eeec0 00000000`74f8ab46 wow64cpu!ServiceNoTurbo+0×28
00000000`016eef50 00000000`74f8a14c wow64!RunCpuSimulation+0xa
00000000`016eef80 00000000`771605a8 wow64!Wow64LdrpInitialize+0×4b4
00000000`016ef4e0 00000000`771168de ntdll! ?? ::FNODOBFM::`string’+0×20aa1
00000000`016ef590 00000000`00000000 ntdll!LdrInitializeThunk+0xe

1: kd> !alpc /m fffff8801c7096e0

Message @ fffff8801c7096e0
  MessageID             : 0x263C (9788)
  CallbackID            : 0x29F2A02 (43985410)
  SequenceNumber        : 0x000009FE (2558)
  Type                  : LPC_REQUEST
  DataLength            : 0x0058 (88)
  TotalLength           : 0x0080 (128)
  Canceled              : No
  Release               : No
  ReplyWaitReply        : No
  Continuation          : Yes
  OwnerPort             : fffffa8015128040 [ALPC_CLIENT_COMMUNICATION_PORT]
  WaitingThread         : fffffa80110b8700
  QueueType             : ALPC_MSGQUEUE_PENDING
  QueuePort             : fffffa8010c9d9a0 [ALPC_CONNECTION_PORT]
  QueuePortOwnerProcess : fffffa80109c8c10 (ProcessB.exe)
  ServerThread          : fffffa8013b87bb0
  QuotaCharged          : No
  CancelQueuePort       : 0000000000000000
  CancelSequencePort    : 0000000000000000
  CancelSequenceNumber  : 0×00000000 (0)
  ClientContext         : 0000000009b49208
  ServerContext         : 0000000000000000
  PortContext           : 000000000280f0d0
  CancelPortContext     : 0000000000000000
  SecurityData          : 0000000000000000
  View                  : 0000000000000000

If we look at process fffffa80109c8c10 and its thread fffffa8013b87bb0 we would see that it is blocked as well on some kind of a lock:

THREAD fffffa8013b87bb0  Cid 0358.2c60  Teb: 000007fffff7e000 Win32Thread: 0000000000000000 WAIT: (UserRequest) UserMode Non-Alertable
    fffffa8010bca370  Semaphore Limit 0x7fffffff
    fffffa8013b87c68  NotificationTimer
Impersonation token:  fffff8801e614060 (Level Impersonation)
DeviceMap                 fffff880097ce5e0
Owning Process            fffffa80109c8c10       Image:         ProcessB.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      14004580       Ticks: 62149 (0:00:16:09.530)
Context Switch Count      134            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address RPCRT4!ThreadStartRoutine (0x000007feff267780)
Stack Init fffffa6035a1fdb0 Current fffffa6035a1f940
Base fffffa6035a20000 Limit fffffa6035a1a000 Call 0
Priority 11 BasePriority 10 PriorityDecrement 0 IoPriority 2 PagePriority 5
Child-SP          RetAddr           Call Site
fffffa60`35a1f980 fffff800`01cba0fa nt!KiSwapContext+0x7f
fffffa60`35a1fac0 fffff800`01caedab nt!KiSwapThread+0x13a
fffffa60`35a1fb30 fffff800`01f1d608 nt!KeWaitForSingleObject+0x2cb
fffffa60`35a1fbc0 fffff800`01cb7973 nt!NtWaitForSingleObject+0x98
fffffa60`35a1fc20 00000000`77136d5a nt!KiSystemServiceCopyEnd+0x13 (TrapFrame @ fffffa60`35a1fc20)
00000000`0486ec28 00000000`770f559f ntdll!ZwWaitForSingleObject+0xa
00000000`0486ec30 00000000`ff77d4e9 ntdll!RtlAcquireResourceShared+0xd1
00000000`0486ec70 00000000`ff77fb4d ProcessB!CLock::CLock+0×61
[…]
00000000`0486eee0 000007fe`ff261f46 RPCRT4!Invoke+0×65
00000000`0486ef40 000007fe`ff26254d RPCRT4!NdrStubCall2+0×348
00000000`0486f520 000007fe`ff2868d4 RPCRT4!NdrServerCall2+0×1d
00000000`0486f550 000007fe`ff2869f0 RPCRT4!DispatchToStubInCNoAvrf+0×14
00000000`0486f580 000007fe`ff287402 RPCRT4!RPC_INTERFACE::DispatchToStubWorker+0×100
00000000`0486f670 000007fe`ff287080 RPCRT4!LRPC_SCALL::DispatchRequest+0×1c2
00000000`0486f6e0 000007fe`ff2862bb RPCRT4!LRPC_SCALL::HandleRequest+0×200
00000000`0486f800 000007fe`ff285e1a RPCRT4!LRPC_ADDRESS::ProcessIO+0×44a
00000000`0486f920 000007fe`ff267769 RPCRT4!LOADABLE_TRANSPORT::ProcessIOEvents+0×24a
00000000`0486f9d0 000007fe`ff267714 RPCRT4!ProcessIOEventsWrapper+0×9
00000000`0486fa00 000007fe`ff2677a4 RPCRT4!BaseCachedThreadRoutine+0×94
00000000`0486fa40 00000000`76fdbe3d RPCRT4!ThreadStartRoutine+0×24
00000000`0486fa70 00000000`77116a51 kernel32!BaseThreadInitThunk+0xd
00000000`0486faa0 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

There are many such threads and inspection of all threads in the process fffffa80109c8c10 reveals another thread waiting for an ALPC reply:

THREAD fffffa8010c9b060  Cid 0358.02ac  Teb: 000007fffffd3000 Win32Thread: 0000000000000000 WAIT: (WrLpcReply) UserMode Non-Alertable
    fffffa8010c9b3f0  Semaphore Limit 0x1
    Waiting for reply to ALPC Message fffff88011994cf0 : queued at port fffffa8010840360 : owned by process fffffa801083e120
Not impersonating
DeviceMap                 fffff880000073d0
Owning Process            fffffa80109c8c10       Image:         ProcessB.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      13986969       Ticks: 79760 (0:00:20:44.263)
Context Switch Count      712            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address ntdll!TppWorkerThread (0×0000000077107cb0)
Stack Init fffffa6004bfbdb0 Current fffffa6004bfb670
Base fffffa6004bfc000 Limit fffffa6004bf6000 Call 0
Priority 10 BasePriority 10 PriorityDecrement 0 IoPriority 2 PagePriority 5
Kernel stack not resident.
Child-SP          RetAddr           Call Site
fffffa60`04bfb6b0 fffff800`01cba0fa nt!KiSwapContext+0×7f
fffffa60`04bfb7f0 fffff800`01caedab nt!KiSwapThread+0×13a
fffffa60`04bfb860 fffff800`01ce4e72 nt!KeWaitForSingleObject+0×2cb
fffffa60`04bfb8f0 fffff800`01f32f34 nt!AlpcpSignalAndWait+0×92
fffffa60`04bfb980 fffff800`01f2f9c6 nt!AlpcpReceiveSynchronousReply+0×44
fffffa60`04bfb9e0 fffff800`01f1f52f nt!AlpcpProcessSynchronousRequest+0×24f
fffffa60`04bfbb00 fffff800`01cb7973 nt!NtAlpcSendWaitReceivePort+0×19f
fffffa60`04bfbbb0 00000000`7713756a nt!KiSystemServiceCopyEnd+0×13 (TrapFrame @ fffffa60`04bfbc20)
00000000`00c3f2f8 00000000`771872c9 ntdll!ZwAlpcSendWaitReceivePort+0xa
[…]
00000000`00c3f810 00000000`77107fd0 ntdll!RtlpTpWorkCallback+0xf2
00000000`00c3f8c0 00000000`76fdbe3d ntdll!TppWorkerThread+0×3d6
00000000`00c3fb40 00000000`77116a51 kernel32!BaseThreadInitThunk+0xd
00000000`00c3fb70 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

1: kd> !alpc /m fffff88011994cf0

Message @ fffff88011994cf0
  MessageID             : 0x033C (828)
  CallbackID            : 0x29CEF57 (43839319)
  SequenceNumber        : 0x000000D8 (216)
  Type                  : LPC_REQUEST
  DataLength            : 0x000C (12)
  TotalLength           : 0x0034 (52)
  Canceled              : No
  Release               : No
  ReplyWaitReply        : No
  Continuation          : Yes
  OwnerPort             : fffffa8010c99040 [ALPC_CLIENT_COMMUNICATION_PORT]
  WaitingThread         : fffffa8010c9b060
  QueueType             : ALPC_MSGQUEUE_PENDING
  QueuePort             : fffffa8010840360 [ALPC_CONNECTION_PORT]
  QueuePortOwnerProcess : fffffa801083e120 (ProcessC.exe)
  ServerThread          : fffffa80109837d0
  QuotaCharged          : No
  CancelQueuePort       : 0000000000000000
  CancelSequencePort    : 0000000000000000
  CancelSequenceNumber  : 0×00000000 (0)
  ClientContext         : 0000000000000000
  ServerContext         : 0000000000000000
  PortContext           : 00000000005f3400
  CancelPortContext     : 0000000000000000
  SecurityData          : 0000000000000000
  View                  : 0000000000000000

We see that ProcessC thread fffffa80109837d0 is waiting for a process object fffffa801434cb40:

THREAD fffffa80109837d0  Cid 027c.02b0  Teb: 000007fffffdb000 Win32Thread: 0000000000000000 WAIT: (UserRequest) UserMode Non-Alertable
    fffffa801434cb40  ProcessObject
Not impersonating
DeviceMap                 fffff880000073d0
Owning Process            fffffa801083e120       Image:         ProcessC.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      13986969       Ticks: 79760 (0:00:20:44.263)
Context Switch Count      520            
UserTime                  00:00:00.000
KernelTime                00:00:00.062
Win32 Start Address 0×000000004826dcf4
Stack Init fffffa6002547db0 Current fffffa6002547940
Base fffffa6002548000 Limit fffffa6002542000 Call 0
Priority 13 BasePriority 11 PriorityDecrement 0 IoPriority 2 PagePriority 5
Kernel stack not resident.
Child-SP          RetAddr           Call Site
fffffa60`02547980 fffff800`01cba0fa nt!KiSwapContext+0×7f
fffffa60`02547ac0 fffff800`01caedab nt!KiSwapThread+0×13a
fffffa60`02547b30 fffff800`01f1d608 nt!KeWaitForSingleObject+0×2cb
fffffa60`02547bc0 fffff800`01cb7973 nt!NtWaitForSingleObject+0×98
fffffa60`02547c20 00000000`77136d5a nt!KiSystemServiceCopyEnd+0×13 (TrapFrame @ fffffa60`02547c20)
00000000`0024f7c8 00000000`4826ea97 ntdll!ZwWaitForSingleObject+0xa
00000000`0024f7d0 00000000`4826ef44 ProcessC!TerminatePID+0xa3
[…]
00000000`0024fc90 00000000`00000000 ntdll!RtlUserThreadStart+0×29

When we inspect process fffffa801434cb40 we see that it has only one thread with many usual threads missing. The blocked thread stack trace has DriverA module code waiting for an event:

1: kd> !process fffffa801434cb40 ff
PROCESS fffffa801434cb40
    SessionId: 1  Cid: a0c8    Peb: 7fffffdc000  ParentCid: 1c08
    DirBase: 19c6cc000  ObjectTable: fffff8801767ee00  HandleCount: 287.
    Image: ProcessD.exe
    VadRoot fffffa8021be17d0 Vads 71 Clone 0 Private 955. Modified 1245. Locked 0.
    DeviceMap fffff880000073d0
    Token                             fffff880187cb3c0
    ElapsedTime                       00:49:23.432
    UserTime                          00:00:00.686
    KernelTime                        00:00:00.904
    QuotaPoolUsage[PagedPool]         208080
    QuotaPoolUsage[NonPagedPool]      6720
    Working Set Sizes (now,min,max)  (2620, 50, 345) (10480KB, 200KB, 1380KB)
    PeakWorkingSetSize                3136
    VirtualSize                       101 Mb
    PeakVirtualSize                   222 Mb
    PageFaultCount                    13495
    MemoryPriority                    BACKGROUND
    BasePriority                      13
    CommitCharge                      1154

[...]

THREAD fffffa8012249b30  Cid a0c8.31b4  Teb: 0000000000000000 Win32Thread: 0000000000000000 WAIT: (Executive) KernelMode Non-Alertable
   fffffa801180a6a0  SynchronizationEvent
   Not impersonating
DeviceMap                 fffff880000073d0
Owning Process            fffffa801434cb40       Image:         ProcessD.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      13986969       Ticks: 79760 (0:00:20:44.263)
Context Switch Count      97            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address DllA (0xfffff96000eeada0)
Stack Init fffffa601b841db0 Current fffffa601b841960
Base fffffa601b842000 Limit fffffa601b83c000 Call 0
Priority 13 BasePriority 13 PriorityDecrement 0 IoPriority 2 PagePriority 5
Child-SP          RetAddr           Call Site
fffffa60`1b8419a0 fffff800`01cba0fa nt!KiSwapContext+0x7f
fffffa60`1b841ae0 fffff800`01caedab nt!KiSwapThread+0x13a
fffffa60`1b841b50 fffff960`00eeb281 nt!KeWaitForSingleObject+0x2cb
fffffa60`1b841c20 fffff800`01ec7bc7 DriverA+0×4b281
fffffa60`1b841d50 fffff800`01cf65a6 nt!PspSystemThreadStartup+0×57
fffffa60`1b841d80 00000000`00000000 nt!KiStartSystemThread+0×16

We therefore recommend to contact the vendor of DriverA component.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Thanks to everyone who submitted their debugger logs. Now VBScript and WinDbg script files are available for download from the CARE page:

http://www.dumpanalysis.org/care

VBScript file scans all hard drives for .DMP files and launches WinDbg to run a mode-independent WinDbg script. Each instance of WinDbg appends the output to dbgeng.log file that you can submit to CARE (please zip it if exceeds 2Mb).

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Computer memory analysis is based on interconnected structures of symbols and we state that there exists a memory language that extends a hierarchy of modeling and implementation languages (both domain-specific and general-purpose):

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

This is a revised, edited, cross-referenced and thematically organized volume of selected DumpAnalysis.org blog posts about crash dump analysis and debugging written in July 2009 - January 2010 for software engineers developing and maintaining products on Windows platforms, quality assurance engineers testing software on Windows platforms and technical support and escalation engineers dealing with complex software issues. The fourth volume features:

- 13 new crash dump analysis patterns
- 13 new pattern interaction case studies
- 10 new trace analysis patterns
- 6 new Debugware patterns and case study
- Workaround patterns
- Updated checklist
- Fully cross-referenced with Volume 1, Volume 2 and Volume 3
- New appendixes

Product information:

• Title: Memory Dump Analysis Anthology, Volume 4
• Author: Dmitry Vostokov
• Language: English
• Product Dimensions: 22.86 x 15.24

• Paperback: 410 pages
• Publisher: Opentask (30 March 2010)
• ISBN-13: 978-1-906717-86-5

• Hardcover: 410 pages
• Publisher: Opentask (30 April 2010)
• ISBN-13: 978-1-906717-87-2

Back cover features memory space art image: Internal Process Combustion.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Another common mistake I observe is relying on what debuggers report without double-checking. Present day debuggers, like WinDbg or GDB, are symbol-driven, they do not possess much of that semantic knowledge that a human debugger has. Also, it is better to report more than less: what is irrelevant can be skipped over by a skilled memory analyst but what looks suspicious to the problem at hand shall be double-checked to see if it is not coincidental. One example we consider here is Coincidental Symbolic Information. 

An application is frequently crashing. The process memory dump file shows only one thread left inside without any exception handling frames. In order to hypothesize about the probable cause the thread raw stack data is analyzed. It shows a few C++ STL calls with a custom smart pointer class and memory allocator like this:

app!std::vector<SmartPtr<ClassA>, std::allocator<SmartPtr<ClassA> > >::operator[]+

WinDbg !analyze-v command output points to this code:

FOLLOWUP_IP:
app!std::bad_alloc::~bad_alloc <PERF> (app+0x0)+0
00400000 4d  dec     ebp

Raw stack data contains a few symbolic references to bad_alloc destructor too:

[...]
0012f9c0  00000100
0012f9c4  00400100 app!std::bad_alloc::~bad_alloc <PERF> (app+0x100)
0012f9c8  00000000
0012f9cc  0012f9b4
0012f9d0  00484488 app!_NULL_IMPORT_DESCRIPTOR+0x1984
0012f9d4  0012fa8c
0012f9d8  7c828290 ntdll!_except_handler3
0012f9dc  0012fa3c
0012f9e0  7c82b04a ntdll!RtlImageNtHeaderEx+0xee
0012f9e4  00482f08 app!_NULL_IMPORT_DESCRIPTOR+0x404
0012f9e8  00151ed0
0012f9ec  00484c1e app!_NULL_IMPORT_DESCRIPTOR+0x211a
0012f9f0  00000100
0012f9f4  00400100 app!std::bad_alloc::~bad_alloc <PERF> (app+0x100)
[...]

By linking all these three pieces together an engineer hypothesized that the cause of failure is memory allocation. However, careful analysis reveals all of them as a coincidental symbolic information and renders hypothesis much less plausible:

1.  The address of app!std::bad_alloc::~bad_alloc is 00400000 which coincides with the start of the main application module:

0:000> lm a 00400000
start    end        module name
00400000 004c4000   app    (no symbols)

As a consequence, its assembly language code makes no sense:

0:000> u 00400000
app:
00400000 4d              dec     ebp
00400001 5a              pop     edx
00400002 90              nop
00400003 0003            add     byte ptr [ebx],al
00400005 0000            add     byte ptr [eax],al
00400007 000400          add     byte ptr [eax+eax],al
0040000a 0000            add     byte ptr [eax],al
0040000c ff              ???

2. All std::vector references are in fact fragments of a UNICODE string that can be dumped using du command:

[...]
0012ef14  00430056 app!std::vector<SmartPtr<ClassA>, std::allocator<SmartPtr<ClassA> > >::operator[]+0x16
0012ef18  00300038
0012ef1c  0043002e app!std::vector<SmartPtr<ClassA>, std::allocator<SmartPtr<ClassA> > >::size+0x1
[...]

0:000> du 0012ef14 l6
0012ef14  "VC80.C"

3. Raw stack data references to bad_alloc destructor are still module addresses in disguise, 00400100 or app+0×100, with nonsense assembly code:

0:000> u 00400100
app+0x100:
00400100 50              push    eax
00400101 45              inc     ebp
00400102 0000            add     byte ptr [eax],al
00400104 4c              dec     esp
00400105 010500571aac    add     dword ptr ds:[0AC1A5700h],eax
0040010b 4a              dec     edx
0040010c 0000            add     byte ptr [eax],al
0040010e 0000            add     byte ptr [eax],al

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

While testing a WinDbg script for the CARE system (the script enumerates files on a Windows PC and processes memory dumps to generate a log file with the output of debugger commands) I found that after successful processing of many files the next launched WinDbg instance suddenly showed this message box:

To find out, I attached another WinDbg instance to its process in order to examine the real command line. In this small case study instead of using kb WinDbg command to show a stack trace and its arguments I employ kn, .frame and kb <lines> commands for visual clarity and to illustrate strack trace frame navigation. In the failed WinDbg instance that had just started we see only one thread showing Message Box pattern:

0:000> ~*kn

.  0  Id: dc8.fb4 Suspend: 1 Teb: 000007ff`fffdc000 Unfrozen
 # Child-SP          RetAddr           Call Site
00 00000000`0025d4b8 00000000`76fc5118 USER32!NtUserWaitMessage+0xa
01 00000000`0025d4c0 00000000`76fc5770 USER32!DialogBox2+0x261
02 00000000`0025d540 00000000`7701000d USER32!InternalDialogBox+0x134
03 00000000`0025d5a0 00000000`7700f2b8 USER32!SoftModalMessageBox+0x9fb
04 00000000`0025d6d0 00000000`7700eb17 USER32!MessageBoxWorker+0x314
05 00000000`0025d890 00000000`7700ea10 USER32!MessageBoxTimeoutW+0xb3
06 00000000`0025d950 00000001`3f9016a6 USER32!MessageBoxW+0x4c
07 00000000`0025d990 00000001`3f90175c WinDbg!TextMsgBox+0x96
08 00000000`0025d9d0 00000001`3f9017d7 WinDbg!FormatMsgBoxV+0x9c
09 00000000`0025dbe0 00000001`3f9075c7 WinDbg!InfoBox+0x37
0a 00000000`0025dc20 00000001`3f9084f7 WinDbg!ParseCommandLine+0x1a57
0b 00000000`0025dcc0 00000001`3f913739 WinDbg!wmain+0×287
0c 00000000`0025fd80 00000000`7708be3d WinDbg!_CxxFrameHandler3+0×291
0d 00000000`0025fdc0 00000000`771c6a51 kernel32!BaseThreadInitThunk+0xd
0e 00000000`0025fdf0 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

We see the frame # 0b contains the return address of wmain function (starting point of execution of UNICODE C/C++ programs) that has this prototype:

int wmain(int argc, wchar_t *argv[], wchar_t *envp[]);

We switch to that frame to examine its first 3 parameters and use kb command that shows stack traces starting from the current frame (we are interested in the top stack trace line only):

0:000> .frame b
0b 00000000`0025dcc0 00000001`3f913739 WinDbg!wmain+0×287

0:000> kb 1
RetAddr           : Args to Child                                                           : Call Site
00000001`3f913739 : 00000000`0000000c 00000000`00278b60 00000000`00279e10 000007de`a4ecc920 : WinDbg!wmain+0×287

Because the function prototype shows the second function parameter as an array of wide character null-terminated strings we use dpu command to dump them. We also note that we have only 0xc array members and use this as the length argument for dpu:

0:000> dpu 00000000`00278b60 Lc
00000000`00278b60  00000000`00278bc8 “C:\Program Files\Debugging Tools for Windows (x64)\WinD”
00000000`00278b68  00000000`00278c44 “-y”
00000000`00278b70  00000000`00278c4a “srv*c:\ms*http://msdl.microsoft.com/download/symbols;sr”
00000000`00278b78  00000000`00278d0c “-z”
00000000`00278b80  00000000`00278d12 “C:\MemoryDumps\CST\ColorimetricTracing”
00000000`00278b88  00000000`00278d60 “(4).DMP”
00000000`00278b90  00000000`00278d70 “-c”
00000000`00278b98  00000000`00278d76 “$$>a<DebuggerLogs.txt;q”
00000000`00278ba0  00000000`00278da6 “-Q”
00000000`00278ba8  00000000`00278dac “-QS”
00000000`00278bb0  00000000`00278db4 “-QY”
00000000`00278bb8  00000000`00278dbc “-QSY”

We see in the output above that “C:\MemoryDumps\CST\ColorimetricTracing” and “(4).DMP” strings were probably split from one file name “C:\MemoryDumps\CST\ColorimetricTracing (4).DMP” and this means that we forgot to enclose the file name parameter in double quotation marks when passing it from VB script to WinDbg.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

These are scripts that can be run without modification in both user and kernel modes to collect information from user and kernel spaces. For example, we want to collect thread stack traces for CARE system and we have different kinds of memory dumps stored on our computer. There is no a single command that can show stack traces for all threads in a process and kernel / complete memory dumps. However, we can combine separate mode-sensitive commands in one script:

.kframes 1000
!for_each_thread !thread @#Thread 1f
~*kv

The first command eliminates the common mistake of truncated traces. The second command fails for process user memory dumps but shows full 3-parameter stack trace for every thread in a system including user space thread stack counterpart for complete memory dumps after switching to the appropriate process context if any. The third command fails for kernel and complete memory dumps but lists stack traces for each thread in a process user memory dump. Therefore, we have just one script that we can run against all memory dumps.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -  

Some practical engineers asked me how do Debugged! MZ/PE magazine back covers look like from a birds eye view:

One engineer even commented that they look better and better (counterclockwise) :-) 

- Dmitry Vostokov @ DumpAnalysis.org -

Google Analytics shows the following crash dump analysis pattern frequencies to be fully analyzed later next week:

- Dmitry Vostokov @ DumpAnalysis.org -

Thanks to Sonny Mir who pointed to !filecache WinDbg command to diagnose low VACB (Virtual Address Control Block or View Address Control Block) conditions I was able to discern another Insufficient Memory pattern for control blocks in general. Certain system and subsystem architectures and designs may put a hard limit on the amount of data structures created to manage resources. If there is a dependency on such resources from other subsystems there could be starvation and blockage conditions resulting in a sluggish system behaviour, absence of a functional response and even in some cases a perceived system, service or application freeze.

7: kd> !filecache
***** Dump file cache******
  Reading and sorting VACBs ...
  Removed 0 nonactive VACBs, processing 1907 active VACBs …
File Cache Information
  Current size 408276 kb
  Peak size    468992 kb
  1907 Control Areas
[…]

I plan to add more insufficient control block case studies including user space.

- Dmitry Vostokov @ DumpAnalysis.org -

“Memory dumps are facts.”

I’m very excited to announce that Volume 3 is available in paperback, hardcover and digital editions:

Memory Dump Analysis Anthology, Volume 3

Table of Contents

In two weeks paperback edition should also appear on Amazon and other bookstores. Amazon hardcover edition is planned to be available in January 2010.

The amount of information was so voluminous that I had to split the originally planned volume into two. Volume 4 should appear by the middle of February together with Color Supplement for Volumes 1-4. 

- Dmitry Vostokov @ DumpAnalysis.org -