Archive for May, 2010

Reading Notebook: 31-May-10

Monday, May 31st, 2010

Comments in italics are mine and express my own views, thoughts and opinions

Windows Internals by M. Russinovich, D. Solomon and A. Ionescu:

Objects vs. account attributes, privilege vs. account right (p. 501)

NtRaiseHardError requires SeShutdownPrivilege (p. 508)

firmware environment variables (p. 508) - some more info: http://msdn.microsoft.com/en-us/library/ms724325(VS.85).aspx

Implication of Bypass Traverse Checking (SeNotifyPrivilege) (p. 509)

Elevated priviliges don’t extend past machine boundaries (p. 510)

Forthcoming Webinars: Complete Debugging and Crash Analysis for Windows

Sunday, May 30th, 2010

Finally, after careful consideration, I’ve come up with the topic that has been neglected so far but at the same time important for both camps (kernel space and user space, including managed space): complete memory dump and software trace analysis. I plan to publish the first webinar agenda early in July and deliver the webinar in August (the date should be finalized by mid July).

PS. Sailing memory spaces under an RGB flag :-)

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

Crash Dump Analysis Patterns (Part 99a)

Saturday, May 29th, 2010

Most of the time Incorrect Symbolic Information is associated with function names and offsets, for example, module!foo vs. module!foo+100. In some cases the module name is incorrect itself or absent altogether. This can happen in complete memory dumps when we forget to reload user space symbols after changing the process context, for example:

; previous process context of firefox.exe
; switching to winlogon.exe context

kd> .process fffffadfe718c040
Implicit process is now fffffadf`e718c040

kd> !process fffffadfe718c040
PROCESS fffffadfe718c040
    SessionId: 0  Cid: 017c    Peb: 7fffffd9000  ParentCid: 0130
    DirBase: 01916000  ObjectTable: fffffa800099a890  HandleCount: 754.
    Image: winlogon.exe
    VadRoot fffffadfe75e91f0 Vads 190 Clone 0 Private 2905. Modified 10047. Locked 0.
    DeviceMap fffffa8000004950
    Token                             fffffa800122a060
    ElapsedTime                       77 Days 02:14:26.109
    UserTime                          00:00:04.156
    KernelTime                        00:00:02.359
    QuotaPoolUsage[PagedPool]         143128
    QuotaPoolUsage[NonPagedPool]      191072
    Working Set Sizes (now,min,max)  (541, 50, 345) (2164KB, 200KB, 1380KB)
    PeakWorkingSetSize                6323
    VirtualSize                       108 Mb
    PeakVirtualSize                   118 Mb
    PageFaultCount                    212547
    MemoryPriority                    BACKGROUND
    BasePriority                      13
    CommitCharge                      3733

[...]

THREAD fffffadfe68f2040  Cid 017c.0198  Teb: 000007fffffd7000 Win32Thread: fffff97ff4a09010 WAIT: (Unknown) UserMode Non-Alertable
    fffffadfe7133160  Semaphore Limit 0x7fffffff
    fffffadfe68f20f8  NotificationTimer
Not impersonating
DeviceMap                 fffffa8000004950
Owning Process            fffffadfe718c040       Image:         winlogon.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      426298731      Ticks: 51 (0:00:00:00.796)
Context Switch Count      2215076                 LargeStack
UserTime                  00:00:00.187
KernelTime                00:00:00.468
Start Address 0×0000000077d6b6e0
Stack Init fffffadfe4481e00 Current fffffadfe4481860
Base fffffadfe4482000 Limit fffffadfe447a000 Call 0
Priority 14 BasePriority 13 PriorityDecrement 0
Child-SP          RetAddr           Call Site
fffffadf`e44818a0 fffff800`0103b093 nt!KiSwapContext+0×85
fffffadf`e4481a20 fffff800`0103c433 nt!KiSwapThread+0xc3
fffffadf`e4481a60 fffff800`012d25ae nt!KeWaitForSingleObject+0×528
fffffadf`e4481af0 fffff800`0104113d nt!NtReplyWaitReceivePortEx+0×8c8
fffffadf`e4481c00 00000000`77ef0caa nt!KiSystemServiceCopyEnd+0×3 (TrapFrame @ fffffadf`e4481c70)
00000000`00bcfb98 000007ff`7fd6ff61 ntdll!NtReplyWaitReceivePortEx+0xa
00000000`00bcfba0 00000000`000d2340 0×7ff`7fd6ff61
00000000`00bcfba8 00000000`00bcfde0 0xd2340
00000000`00bcfbb0 00000000`014cd220 0xbcfde0
00000000`00bcfbb8 00000000`000c1d30 0×14cd220
00000000`00bcfbc0 00000000`00bcfe18 0xc1d30
00000000`00bcfbc8 0000ffff`00001f80 0xbcfe18
00000000`00bcfbd0 00000000`006c0044 0xffff`00001f80
00000000`00bcfbd8 00000000`000006ec firefox+0×2c0044
00000000`00bcfbe0 00000000`000007b0 0×6ec
00000000`00bcfbe8 00000000`419b8385 0×7b0
00000000`00bcfbf0 00000000`00000000 0×419b8385

kd> lmu m firefox
start             end                 module name
00000000`00400000 00000000`00b67000   firefox  T (no symbols)

We have the return address 00000000`006c0044 which is just firefox+0×2c0044 (00000000`00400000 + 2c0044). We correct that by reloading user space symbols.

kd> .reload /user

kd> !process fffffadfe718c040
[...]
THREAD fffffadfe68f2040  Cid 017c.0198  Teb: 000007fffffd7000 Win32Thread: fffff97ff4a09010 WAIT: (Unknown) UserMode Non-Alertable
    fffffadfe7133160  Semaphore Limit 0x7fffffff
    fffffadfe68f20f8  NotificationTimer
Not impersonating
DeviceMap                 fffffa8000004950
Owning Process            fffffadfe718c040       Image:         winlogon.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      426298731      Ticks: 51 (0:00:00:00.796)
Context Switch Count      2215076                 LargeStack
UserTime                  00:00:00.187
KernelTime                00:00:00.468
Start Address kernel32!BaseThreadStart (0x0000000077d6b6e0)
Stack Init fffffadfe4481e00 Current fffffadfe4481860
Base fffffadfe4482000 Limit fffffadfe447a000 Call 0
Priority 14 BasePriority 13 PriorityDecrement 0
Child-SP          RetAddr           Call Site
fffffadf`e44818a0 fffff800`0103b093 nt!KiSwapContext+0x85
fffffadf`e4481a20 fffff800`0103c433 nt!KiSwapThread+0xc3
fffffadf`e4481a60 fffff800`012d25ae nt!KeWaitForSingleObject+0x528
fffffadf`e4481af0 fffff800`0104113d nt!NtReplyWaitReceivePortEx+0x8c8
fffffadf`e4481c00 00000000`77ef0caa nt!KiSystemServiceCopyEnd+0x3 (TrapFrame @ fffffadf`e4481c70)
00000000`00bcfb98 000007ff`7fd6ff61 ntdll!NtReplyWaitReceivePortEx+0xa
00000000`00bcfba0 000007ff`7fd45369 RPCRT4!LRPC_ADDRESS::ReceiveLotsaCalls+0x2a5
00000000`00bcfeb0 000007ff`7fd65996 RPCRT4!RecvLotsaCallsWrapper+0x9
00000000`00bcfee0 000007ff`7fd65d51 RPCRT4!BaseCachedThreadRoutine+0xde
00000000`00bcff50 00000000`77d6b71a RPCRT4!ThreadStartRoutine+0x21
00000000`00bcff80 00000000`00000000 kernel32!BaseThreadStart+0x3a

Commands like .process /r /p fffffadfe718c040 or !process fffffadfe718c040 ff do that automatically.

Another case for incorrect module names is malformed unloaded modules information. This can happen sometimes:

0:000> lmt
start    end        module name
[...]
7c800000 7c907000   kernel32  Mon Apr 16 16:53:05 2007 (46239BE1)
7c910000 7c9c7000   ntdll     Wed Aug 04 08:57:08 2004 (411096D4)
7c9d0000 7d1ef000   shell32   Tue Dec 19 21:49:37 2006 (45885E71)
7df20000 7dfc0000   urlmon    Wed Aug 22 14:13:03 2007 (46CC365F)
7e360000 7e3f0000   user32    Thu Mar 08 15:36:30 2007 (45F02D7E)
Missing image name, possible paged-out or corrupt data.

Unloaded modules:
00410053 008a00a3   Unknown_Module_00410053
    Timestamp: Tue Mar 17 20:27:26 1970 (0064002E)
    Checksum:  006C006C
00010755 007407c5   l      
    Timestamp: Wed Feb 04 21:26:01 1970 (002E0069)
    Checksum:  006C0064
00000011 411096d2   eme.dll
    Timestamp: Thu Apr 02 01:33:25 1970 (00780055)
    Checksum:  00680054
Missing image name, possible paged-out or corrupt data.
0064002e 00d0009a   Unknown_Module_0064002e
    Timestamp: unavailable (00000000)
    Checksum:  00000000

Here parts of UNICODE module names appear in checksums and timestamps as well. Such partial module names can appear on thread stacks and raw stack data, for example:

0:000> kL
ChildEBP RetAddr
[...]
0015ef3c 0366afc2 ModuleA!Validation+0x5b
WARNING: Frame IP not in any known module. Following frames may be wrong.
0015efcc 79e7c7a6 <Unloaded_ure.dll>+0x366afc1
03dc9b70 00000000 mscorwks!MethodDesc::CallDescr+0x1f

Default analysis falls victim too and suggests ure.dll you would try hard to find on your system:

MODULE_NAME: ure

IMAGE_NAME:  ure.dll

DEBUG_FLR_IMAGE_TIMESTAMP:  750063

FAILURE_BUCKET_ID:  ure.dll!Unloaded_c0000005_APPLICATION_FAULT

Timestamp is suspiciously UNICODE-like. In such cases we can even reconstruct the module name:

00000011 411096d2   eme.dll
    Timestamp: Thu Apr 02 01:33:25 1970 (00780055)
    Checksum:  00680054

0:000> .formats 00780055
Evaluate expression:
  Hex:     00000000`00780055
  Decimal: 7864405
  Octal:   0000000000000036000125
  Binary:  00000000 00000000 00000000 00000000 00000000 01111000 00000000 01010101
  Chars:   …..x.U
  Time:    Thu Apr 02 01:33:25 1970
  Float:   low 1.10204e-038 high 0
  Double:  3.88553e-317

0:000> .formats 00680054
Evaluate expression:
  Hex:     00680054
  Decimal: 6815828
  Octal:   00032000124
  Binary:  00000000 01101000 00000000 01010100
  Chars:   .h.T
  Time:    Fri Mar 20 21:17:08 1970
  Float:   low 9.55101e-039 high 0
  Double:  3.36747e-317

We concatenate UNICODE Ux and Th with eme.dll to get UxTheme.dll which is a real DLL name we can find on a system.

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

Icons for Memory Dump Analysis Patterns (Part 44)

Friday, May 28th, 2010

Today we introduce an icon for Stack Trace pattern:

B/W

Color

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

Reading Notebook: 26-May-10

Thursday, May 27th, 2010

Comments in italics are mine and express my own views, thoughts and opinions

Windows Internals by M. Russinovich, D. Solomon and A. Ionescu:

Explicit ACE are ahead of inherited (p. 491)

Differences of inheritable ACE propagation AD objects (p. 491)

Ntmarta.dll: security inheritance support DLL (p. 492)

SeAccessCheck optimization: integrity check -> DACL check (p. 492)

Low and medium integrity processes can read high integrity objects (p. 493)

UIPI safe messages, shatter attacks, blocked (journal) hooks (pp. 493 - 494)

Owner Rights SID (pp. 495 - 496)

Importance of ACE ordering (pp. 497 - 498)

Security editors place Deny ACE on top, Advanced Settings and Effective Permissions (pp. 498 - 500)

AuthZ API: security model in user mode (pp. 500 - 501)

Icons for Memory Dump Analysis Patterns (Part 43)

Wednesday, May 26th, 2010

Today we introduce an icon for Coincidental Symbolic Information pattern:

B/W

Color

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

Reading Notebook: 25-May-10

Tuesday, May 25th, 2010

Comments in italics are mine and express my own views, thoughts and opinions

Windows Internals by M. Russinovich, D. Solomon and A. Ionescu:

No share access for impersonation: we need logon  (p. 481)

S(ecure)QOS levels, SECURITY_CONTEXT_TRACKING (p. 482)

Integrity Level (client) <= Integrity Level (server) (pp. 482 - 483)

Restricted tokens -> filtered admin tokens (logon as admin with UAC) (pp. 483 - 484)

Callback, allowed(denied)-object (GUID-based for AD) ACEs (p. 487)

No DACL: full access, empty DACL: no access (p. 487)

System audit-object ACEs (p. 488)

Software Trace Analysis Tools: CDFMarker

Tuesday, May 25th, 2010

Finally Citrix has published a tool (written by my colleague Colm Naish, lead escalation engineer) that allows controlled injection of events into CDF (ETW) trace message stream. This is useful in many troubleshooting scenarios where we need to rely on Significant Event and Anchor Message analysis patterns to partition traces into artificial Activity Regions to start our analysis with. This is also analogous for the imposition of the external time on the stream of tracing events from software narratology perspective:

CDFMarker On Demand - For XenApp and XenDesktop

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

Reading Notebook: 24-May-10

Monday, May 24th, 2010

Comments in italics are mine and express my own views, thoughts and opinions

Windows Internals by M. Russinovich, D. Solomon and A. Ionescu:

Process integrity levels as SIDs (pp. 464 - 465)

Protected mode IE startup sequence (pp. 467 - 470) - ieuser.exe might block several iexplore.exe instances: http://www.dumpanalysis.org/blog/index.php/2009/02/11/stack-trace-collection-blocked-thread-and-coupled-processes-pattern-cooperation/

Integrity levels and mandatory policies for objects (pp. 471- 473)

Many faces of an Administrator, filtered admin tokens (p. 474)

CreateProcessWithLogonW (p. 474)

The token source field (p. 476)

Token authentication and modified IDs (pp. 476 - 477) - token structure from x64 Windows Server R2:

0: kd> dt _TOKEN
nt!_TOKEN
+0x000 TokenSource      : _TOKEN_SOURCE
+0x010 TokenId          : _LUID
+0x018 AuthenticationId : _LUID
+0x020 ParentTokenId    : _LUID
+0x028 ExpirationTime   : _LARGE_INTEGER
+0x030 TokenLock        : Ptr64 _ERESOURCE
+0x038 ModifiedId       : _LUID
+0x040 Privileges       : _SEP_TOKEN_PRIVILEGES
+0x058 AuditPolicy      : _SEP_AUDIT_POLICY
+0x074 SessionId        : Uint4B
+0x078 UserAndGroupCount : Uint4B
+0x07c RestrictedSidCount : Uint4B
+0x080 VariableLength   : Uint4B
+0x084 DynamicCharged   : Uint4B
+0x088 DynamicAvailable : Uint4B
+0x08c DefaultOwnerIndex : Uint4B
+0x090 UserAndGroups    : Ptr64 _SID_AND_ATTRIBUTES
+0x098 RestrictedSids   : Ptr64 _SID_AND_ATTRIBUTES
+0x0a0 PrimaryGroup     : Ptr64 Void
+0x0a8 DynamicPart      : Ptr64 Uint4B
+0x0b0 DefaultDacl      : Ptr64 _ACL
+0x0b8 TokenType        : _TOKEN_TYPE
+0x0bc ImpersonationLevel : _SECURITY_IMPERSONATION_LEVEL
+0x0c0 TokenFlags       : Uint4B
+0x0c4 TokenInUse       : UChar
+0x0c8 IntegrityLevelIndex : Uint4B
+0x0cc MandatoryPolicy  : Uint4B
+0x0d0 LogonSession     : Ptr64 _SEP_LOGON_SESSION_REFERENCES
+0x0d8 OriginatingLogonSession : _LUID
+0x0e0 SidHash          : _SID_AND_ATTRIBUTES_HASH
+0x1f0 RestrictedSidHash : _SID_AND_ATTRIBUTES_HASH
+0x300 pSecurityAttributes : Ptr64 _AUTHZBASEP_SECURITY_ATTRIBUTES_INFORMATION
+0x308 VariablePart     : Uint8B

Models for Memory and Trace Analysis Patterns (Part 2)

Sunday, May 23rd, 2010

We continue our modeling of software behaviour with the ubiquitous Memory Leak (process heap) pattern. Instead of leaking small heap allocations that are easy to debug with user mode stack trace database our model program leaks large heap allocations:

// MemoryLeak-ProcessHeap
// Copyright (c) 2010 Dmitry Vostokov
// GNU GENERAL PUBLIC LICENSE
// http://www.gnu.org/licenses/gpl-3.0.txt

#include <windows.h>

int _tmain(int argc, _TCHAR* argv[])
{
 // create extra 25 heaps initially
 for (int i = 0; i < 25; ++i)
  HeapCreate(0, 0, 0);

 
 // create a heap to leak within
 HANDLE hHeap = HeapCreate(0, 0, 0);

 while (true)
 {
  HeapAlloc(hHeap, 0, 1024*1024);
  Sleep(1000);
 }

 return 0;
}

The program creates extra process heaps to simulate real life heap leaks that usually happen not in a default process heap. Then it slowly leaks 0×100000 bytes every second. The application can be downloaded from here (zip file contains source code, x86 and x64 binaries together with corresponding PDB files):

Download MemoryLeak-ProcessHeap.zip

Here I present the results from x64 Windows Server 2008 R2 but x86 variants (I tested on x86 Vista) should be the same.

First we run the application and save a dump of it after a few seconds (I used Task Manager). Heap statistics shows 9 virtual blocks for the last 0000000001e00000 heap:

0:000> !heap -s
LFH Key                   : 0x000000d529c37801
Termination on corruption : ENABLED
          Heap     Flags   Reserv  Commit  Virt   Free  List   UCR  Virt  Lock  Fast
                            (k)     (k)    (k)     (k) length      blocks cont. heap
————————————————————————————-
00000000002b0000 00000002    1024    164   1024      3     1     1    0      0   LFH
0000000000010000 00008000      64      4     64      1     1     1    0      0     
0000000000020000 00008000      64     64     64     61     1     1    0      0     
0000000000220000 00001002    1088    152   1088      3     2     2    0      0   LFH
0000000000630000 00001002     512      8    512      3     1     1    0      0     
0000000000870000 00001002     512      8    512      3     1     1    0      0     
0000000000ad0000 00001002     512      8    512      3     1     1    0      0     
00000000007e0000 00001002     512      8    512      3     1     1    0      0     
0000000000cc0000 00001002     512      8    512      3     1     1    0      0     
0000000000ed0000 00001002     512      8    512      3     1     1    0      0     
00000000010c0000 00001002     512      8    512      3     1     1    0      0     
00000000005b0000 00001002     512      8    512      3     1     1    0      0     
00000000009f0000 00001002     512      8    512      3     1     1    0      0     
00000000004d0000 00001002     512      8    512      3     1     1    0      0     
0000000000230000 00001002     512      8    512      3     1     1    0      0     
0000000000700000 00001002     512      8    512      3     1     1    0      0     
00000000012d0000 00001002     512      8    512      3     1     1    0      0     
0000000000950000 00001002     512      8    512      3     1     1    0      0     
0000000000b90000 00001002     512      8    512      3     1     1    0      0     
00000000014c0000 00001002     512      8    512      3     1     1    0      0     
0000000000e50000 00001002     512      8    512      3     1     1    0      0     
0000000001020000 00001002     512      8    512      3     1     1    0      0     
00000000016e0000 00001002     512      8    512      3     1     1    0      0     
0000000001940000 00001002     512      8    512      3     1     1    0      0     
0000000001b90000 00001002     512      8    512      3     1     1    0      0     
0000000001200000 00001002     512      8    512      3     1     1    0      0     
0000000000c20000 00001002     512      8    512      3     1     1    0      0     
0000000000db0000 00001002     512      8    512      3     1     1    0      0     
0000000000f50000 00001002     512      8    512      3     1     1    0      0     
Virtual block: 0000000001350000 - 0000000001350000 (size 0000000000000000)
Virtual block: 0000000001540000 - 0000000001540000 (size 0000000000000000)
Virtual block: 0000000001760000 - 0000000001760000 (size 0000000000000000)
Virtual block: 00000000019c0000 - 00000000019c0000 (size 0000000000000000)
Virtual block: 0000000001c10000 - 0000000001c10000 (size 0000000000000000)
Virtual block: 0000000001e80000 - 0000000001e80000 (size 0000000000000000)
Virtual block: 0000000001f90000 - 0000000001f90000 (size 0000000000000000)
Virtual block: 00000000020a0000 - 00000000020a0000 (size 0000000000000000)
Virtual block: 00000000021b0000 - 00000000021b0000 (size 0000000000000000)
0000000001e00000 00001002     512      8    512      3     1     1    9      0     

————————————————————————————-

We then wait for a few minutes and save a memory dump again. Heap statistics clearly shows virtual block leaks because now we 276 of them instead of previous 9 (I skipped most of them in the output below):

0:000> !heap -s
LFH Key                   : 0x000000d529c37801
Termination on corruption : ENABLED
          Heap     Flags   Reserv  Commit  Virt   Free  List   UCR  Virt  Lock  Fast
                            (k)     (k)    (k)     (k) length      blocks cont. heap
————————————————————————————-
00000000002b0000 00000002    1024    164   1024      3     1     1    0      0   LFH
0000000000010000 00008000      64      4     64      1     1     1    0      0     
0000000000020000 00008000      64     64     64     61     1     1    0      0     
0000000000220000 00001002    1088    152   1088      3     2     2    0      0   LFH
0000000000630000 00001002     512      8    512      3     1     1    0      0     
0000000000870000 00001002     512      8    512      3     1     1    0      0     
0000000000ad0000 00001002     512      8    512      3     1     1    0      0     
00000000007e0000 00001002     512      8    512      3     1     1    0      0     
0000000000cc0000 00001002     512      8    512      3     1     1    0      0     
0000000000ed0000 00001002     512      8    512      3     1     1    0      0     
00000000010c0000 00001002     512      8    512      3     1     1    0      0     
00000000005b0000 00001002     512      8    512      3     1     1    0      0     
00000000009f0000 00001002     512      8    512      3     1     1    0      0     
00000000004d0000 00001002     512      8    512      3     1     1    0      0     
0000000000230000 00001002     512      8    512      3     1     1    0      0     
0000000000700000 00001002     512      8    512      3     1     1    0      0     
00000000012d0000 00001002     512      8    512      3     1     1    0      0     
0000000000950000 00001002     512      8    512      3     1     1    0      0     
0000000000b90000 00001002     512      8    512      3     1     1    0      0     
00000000014c0000 00001002     512      8    512      3     1     1    0      0     
0000000000e50000 00001002     512      8    512      3     1     1    0      0     
0000000001020000 00001002     512      8    512      3     1     1    0      0     
00000000016e0000 00001002     512      8    512      3     1     1    0      0     
0000000001940000 00001002     512      8    512      3     1     1    0      0     
0000000001b90000 00001002     512      8    512      3     1     1    0      0     
0000000001200000 00001002     512      8    512      3     1     1    0      0     
0000000000c20000 00001002     512      8    512      3     1     1    0      0     
0000000000db0000 00001002     512      8    512      3     1     1    0      0     
0000000000f50000 00001002     512      8    512      3     1     1    0      0     
Virtual block: 0000000001350000 - 0000000001350000 (size 0000000000000000)
Virtual block: 0000000001540000 - 0000000001540000 (size 0000000000000000)
Virtual block: 0000000001760000 - 0000000001760000 (size 0000000000000000)
Virtual block: 00000000019c0000 - 00000000019c0000 (size 0000000000000000)
[… skipped …]
Virtual block: 00000000131b0000 - 00000000131b0000 (size 0000000000000000)
Virtual block: 00000000132c0000 - 00000000132c0000 (size 0000000000000000)
Virtual block: 00000000133d0000 - 00000000133d0000 (size 0000000000000000)
Virtual block: 00000000134e0000 - 00000000134e0000 (size 0000000000000000)
Virtual block: 00000000135f0000 - 00000000135f0000 (size 0000000000000000)
Virtual block: 0000000013700000 - 0000000013700000 (size 0000000000000000)
Virtual block: 0000000013810000 - 0000000013810000 (size 0000000000000000)
Virtual block: 0000000013920000 - 0000000013920000 (size 0000000000000000)
Virtual block: 0000000013a30000 - 0000000013a30000 (size 0000000000000000)
Virtual block: 0000000013b40000 - 0000000013b40000 (size 0000000000000000)
Virtual block: 0000000013c50000 - 0000000013c50000 (size 0000000000000000)
Virtual block: 0000000013d60000 - 0000000013d60000 (size 0000000000000000)
0000000001e00000 00001002     512      8    512      3     1     1  276      0     

————————————————————————————-

We see that size of these blocks is 0×101000 bytes (with hindsight, extra 1000 is probably bookkeeping info):

0:000> !address 0000000013d60000
 ProcessParametrs 00000000002b1f20 in range 00000000002b0000 00000000002d9000
 Environment 00000000002b1320 in range 00000000002b0000 00000000002d9000
    0000000013d60000 : 0000000013d60000 - 0000000000101000
                    Type     00020000 MEM_PRIVATE
                    Protect  00000004 PAGE_READWRITE
                    State    00001000 MEM_COMMIT
                    Usage    RegionUsageHeap
                    Handle   0000000001e00000

We want to know which thread allocates them and we search for the heap address 0000000001e00000 through virtual memory to find any execution residue on thread raw stacks:

0:000> s -q 0 LFFFFFF 0000000001e00000
00000000`001cf608  00000000`01e00000 00000000`01e00000
00000000`001cf610  00000000`01e00000 00000000`00000858
00000000`001cf630  00000000`01e00000 00000000`0000000a
00000000`001cf6c8  00000000`01e00000 00000000`00000000
00000000`001cf6e0  00000000`01e00000 00000000`01e00a80
00000000`001cf720  00000000`01e00000 00000000`00000020
00000000`001cf778  00000000`01e00000 00000000`01e00000
00000000`001cf780  00000000`01e00000 00000000`00000000
00000000`001cf798  00000000`01e00000 00000000`01e02000
00000000`001cf7b0  00000000`01e00000 02100301`00000000
00000000`001cf7c8  00000000`01e00000 00000000`01c10000
00000000`001cf808  00000000`01e00000 00000000`00000001
00000000`001cf830  00000000`01e00000 00000000`00000002
00000000`001cf940  00000000`01e00000 00000000`00000000
00000000`002d8378  00000000`01e00000 004c0044`005c0064
00000000`01e00028  00000000`01e00000 00000000`01e00000
00000000`01e00030  00000000`01e00000 00000000`00000080

Address range 00000000`001cfxxxx belongs to the main thread:

0:000> kL
Child-SP          RetAddr           Call Site
00000000`001cf898 000007fe`fdd91203 ntdll!NtDelayExecution+0xa
00000000`001cf8a0 00000001`3f39104f KERNELBASE!SleepEx+0xab
00000000`001cf940 00000001`3f3911ea MemoryLeak_ProcessHeap!wmain+0×4f
00000000`001cf970 00000000`778cf56d MemoryLeak_ProcessHeap!__tmainCRTStartup+0×15a
00000000`001cf9b0 00000000`77b03281 kernel32!BaseThreadInitThunk+0xd
00000000`001cf9e0 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

We dump the raw stack fragment now:

0:000> dps 00000000`001cf608 00000000`001cf940
00000000`001cf608  00000000`01e00000
00000000`001cf610  00000000`01e00000
00000000`001cf618  00000000`00000858
00000000`001cf620  00000000`00000000
00000000`001cf628  00000000`77b229ac ntdll!RtlAllocateHeap+0×16c
00000000`001cf630  00000000`01e00000
00000000`001cf638  00000000`0000000a
00000000`001cf640  00000000`00000858
00000000`001cf648  00000000`00000860
00000000`001cf650  00000000`00000000
00000000`001cf658  00000000`001cf740
00000000`001cf660  00000020`00001000
00000000`001cf668  fffff680`01000000
00000000`001cf670  00000001`3f390000 MemoryLeak_ProcessHeap!wmain <PERF> (MemoryLeak_ProcessHeap+0×0)
00000000`001cf678  01000000`00000080
00000000`001cf680  00000000`0000f000
00000000`001cf688  02100210`02100210
00000000`001cf690  00000001`3f390000 MemoryLeak_ProcessHeap!wmain <PERF> (MemoryLeak_ProcessHeap+0×0)
00000000`001cf698  00000000`0000f000
00000000`001cf6a0  00000000`01e01fd0
00000000`001cf6a8  00000000`77b07ff3 ntdll!RtlpCreateUCREntry+0xb3
00000000`001cf6b0  00000000`001cf6b8
00000000`001cf6b8  00000000`01e01fc0
00000000`001cf6c0  00000000`00000080
00000000`001cf6c8  00000000`01e00000
00000000`001cf6d0  00000000`00000000
00000000`001cf6d8  00000000`00000a00
00000000`001cf6e0  00000000`01e00000
00000000`001cf6e8  00000000`01e00a80
00000000`001cf6f0  00000000`0007e000
00000000`001cf6f8  00000000`77b0f2bb ntdll!RtlpInitializeHeapSegment+0×19b
00000000`001cf700  00000000`01e00208
00000000`001cf708  00000000`00000000
00000000`001cf710  00000000`01e00230
00000000`001cf718  00000000`00000000
00000000`001cf720  00000000`01e00000
00000000`001cf728  00000000`00000020
00000000`001cf730  00000000`00000000
00000000`001cf738  00000000`77b0f676 ntdll!RtlpInitializeUCRIndex+0×36
00000000`001cf740  000007ff`00000003
00000000`001cf748  00000000`00000100
00000000`001cf750  00000000`00000000
00000000`001cf758  00000000`00001002
00000000`001cf760  00000000`00001002
00000000`001cf768  00000000`77b0fec9 ntdll!RtlCreateHeap+0×8f7
00000000`001cf770  00000000`01e02000
00000000`001cf778  00000000`01e00000
00000000`001cf780  00000000`01e00000
00000000`001cf788  00000000`00000000
00000000`001cf790  03010301`00000000
00000000`001cf798  00000000`01e00000
00000000`001cf7a0  00000000`01e02000
00000000`001cf7a8  00000000`01e80000
00000000`001cf7b0  00000000`01e00000
00000000`001cf7b8  02100301`00000000
00000000`001cf7c0  00000000`001f0000
00000000`001cf7c8  00000000`01e00000
00000000`001cf7d0  00000000`01c10000
00000000`001cf7d8  00000000`01e02000
00000000`001cf7e0  00000000`00270000
00000000`001cf7e8  03020302`00000230
00000000`001cf7f0  00000000`77be7288 ntdll!RtlpInterceptorRoutines
00000000`001cf7f8  00000000`00000000
00000000`001cf800  00000000`00100010
00000000`001cf808  00000000`01e00000
00000000`001cf810  00000000`00000001
00000000`001cf818  00000000`00100000
00000000`001cf820  00000000`00000000
00000000`001cf828  00000000`77b229ac ntdll!RtlAllocateHeap+0×16c
00000000`001cf830  00000000`01e00000
00000000`001cf838  00000000`00000002
00000000`001cf840  00000000`00100000
00000000`001cf848  00000000`00101000
00000000`001cf850  00000000`00000000
00000000`001cf858  00000000`001cf940
00000000`001cf860  00000000`00000000
00000000`001cf868  0000f577`2bd1e0ff
00000000`001cf870  00000000`ffffffff
00000000`001cf878  00000000`10010011
00000000`001cf880  00000000`c00000bb
00000000`001cf888  00000000`00000000
00000000`001cf890  00000000`00000100
00000000`001cf898  000007fe`fdd91203 KERNELBASE!SleepEx+0xab
00000000`001cf8a0  00000000`001cf958
00000000`001cf8a8  00000000`00000000
00000000`001cf8b0  00000000`00000000
00000000`001cf8b8  00000000`00000012
00000000`001cf8c0  ffffffff`ff676980
00000000`001cf8c8  00000000`001cf8c0
00000000`001cf8d0  00000000`00000048
00000000`001cf8d8  00000000`00000001
00000000`001cf8e0  00000000`00000000
00000000`001cf8e8  00000000`00000000
00000000`001cf8f0  00000000`00000000
00000000`001cf8f8  00000000`00000000
00000000`001cf900  00000000`00000000
00000000`001cf908  00000000`00000000
00000000`001cf910  00000000`00000000
00000000`001cf918  00000000`00000000
00000000`001cf920  00000000`00000000
00000000`001cf928  00000000`00000001
00000000`001cf930  00000000`00000000
00000000`001cf938  00000001`3f39104f MemoryLeak_ProcessHeap!wmain+0×4f
00000000`001cf940  00000000`01e00000

We see traces of RtlAllocateHeap but it could be a coincidence (imagine that we don’t have access to source code and can’t do live debugging to put breakpoints). We advise to enable use mode stack trace database as explained for another example process: CTX106970. Then we launch our application again and save a new user dump. We repeat the same procedure to examine the raw stack:

0:000> !heap -s
NtGlobalFlag enables following debugging aids for new heaps:
    stack back traces
LFH Key                   : 0x000000c21e1b31e6
Termination on corruption : ENABLED
          Heap     Flags   Reserv  Commit  Virt   Free  List   UCR  Virt  Lock  Fast
                            (k)     (k)    (k)     (k) length      blocks cont. heap
-------------------------------------------------------------------------------------
0000000001bc0000 08000002    1024    168   1024      5     1     1    0      0   LFH
0000000000010000 08008000      64      4     64      1     1     1    0      0     
0000000000020000 08008000      64     64     64     61     1     1    0      0     
0000000000100000 08001002    1088    152   1088      2     2     2    0      0   LFH
0000000001d90000 08001002     512      8    512      3     1     1    0      0     
0000000001f90000 08001002     512      8    512      3     1     1    0      0     
00000000021c0000 08001002     512      8    512      3     1     1    0      0     
0000000002130000 08001002     512      8    512      3     1     1    0      0     
0000000002370000 08001002     512      8    512      3     1     1    0      0     
0000000001e80000 08001002     512      8    512      3     1     1    0      0     
0000000000110000 08001002     512      8    512      3     1     1    0      0     
0000000002510000 08001002     512      8    512      3     1     1    0      0     
0000000002760000 08001002     512      8    512      3     1     1    0      0     
0000000001cc0000 08001002     512      8    512      3     1     1    0      0     
0000000002030000 08001002     512      8    512      3     1     1    0      0     
0000000002960000 08001002     512      8    512      3     1     1    0      0     
0000000002670000 08001002     512      8    512      3     1     1    0      0     
0000000002b90000 08001002     512      8    512      3     1     1    0      0     
00000000022f0000 08001002     512      8    512      3     1     1    0      0     
00000000028b0000 08001002     512      8    512      3     1     1    0      0     
0000000001f10000 08001002     512      8    512      3     1     1    0      0     
0000000002450000 08001002     512      8    512      3     1     1    0      0     
00000000025f0000 08001002     512      8    512      3     1     1    0      0     
0000000002a40000 08001002     512      8    512      3     1     1    0      0     
0000000002c90000 08001002     512      8    512      3     1     1    0      0     
0000000002d90000 08001002     512      8    512      3     1     1    0      0     
0000000002e80000 08001002     512      8    512      3     1     1    0      0     
0000000002fc0000 08001002     512      8    512      3     1     1    0      0     
00000000030b0000 08001002     512      8    512      3     1     1    0      0     
Virtual block: 0000000003130000 - 0000000003130000 (size 0000000000000000)
Virtual block: 0000000003240000 - 0000000003240000 (size 0000000000000000)
Virtual block: 0000000003350000 - 0000000003350000 (size 0000000000000000)
Virtual block: 0000000003460000 - 0000000003460000 (size 0000000000000000)
Virtual block: 0000000003570000 - 0000000003570000 (size 0000000000000000)
Virtual block: 0000000003680000 - 0000000003680000 (size 0000000000000000)
Virtual block: 0000000003790000 - 0000000003790000 (size 0000000000000000)
Virtual block: 00000000038a0000 - 00000000038a0000 (size 0000000000000000)
Virtual block: 00000000039b0000 - 00000000039b0000 (size 0000000000000000)
Virtual block: 0000000003ac0000 - 0000000003ac0000 (size 0000000000000000)
Virtual block: 0000000003bd0000 - 0000000003bd0000 (size 0000000000000000)
Virtual block: 0000000003ce0000 - 0000000003ce0000 (size 0000000000000000)
0000000002270000 08001002     512      8    512      3     1     1   12      0     

0:000> s -q 0 LFFFFFF 0000000002270000
00000000`0029f648  00000000`02270000 00000000`000000a8
00000000`0029f660  00000000`02270000 00000000`77b99bc7
00000000`0029f6e8  00000000`02270000 00000000`02270000
00000000`0029f6f0  00000000`02270000 00000000`00000858
00000000`0029f710  00000000`02270000 00000000`0000000a
00000000`0029f758  00000000`02270000 00000000`0029f918
00000000`0029f7c0  00000000`02270000 00000000`03ce0040
00000000`0029f858  00000000`02270000 00000000`02270000
00000000`0029f860  00000000`02270000 00000000`00000000
00000000`0029f878  00000000`02270000 00000000`02272000
00000000`0029f890  00000000`02270000 02100301`00000000
00000000`0029f8f8  00000000`02270000 00000000`03ce0040
00000000`0029fa20  00000000`02270000 00000000`00000000
00000000`01be8a08  00000000`02270000 0064006e`00690057
00000000`02270028  00000000`02270000 00000000`02270000
00000000`02270030  00000000`02270000 00000000`00000080

0:000> dqs 00000000`0029f648 00000000`0029fa20
00000000`0029f648  00000000`02270000
00000000`0029f650  00000000`000000a8
00000000`0029f658  00000000`00000a80
00000000`0029f660  00000000`02270000
00000000`0029f668  00000000`77b99bc7 ntdll!RtlStdLogStackTrace+0x47
00000000`0029f670  00000000`002a0000
00000000`0029f678  00000000`0000007e
00000000`0029f680  00000000`02270a80
00000000`0029f688  00000000`00000000
00000000`0029f690  00000000`02270208
00000000`0029f698  00070000`77b99bc7
00000000`0029f6a0  00000000`77b6cd8a ntdll! ?? ::FNODOBFM::`string'+0xf35a
00000000`0029f6a8  00000000`77b0fd07 ntdll!RtlCreateHeap+0x56e
00000000`0029f6b0  000007fe`fdd9c6a4 KERNELBASE!HeapCreate+0x54
00000000`0029f6b8  00000001`3faa1030 MemoryLeak_ProcessHeap!wmain+0x30
00000000`0029f6c0  00000001`3faa11ea MemoryLeak_ProcessHeap!__tmainCRTStartup+0x15a
00000000`0029f6c8  00000000`778cf56d kernel32!BaseThreadInitThunk+0xd
00000000`0029f6d0  00000000`77be7288 ntdll!RtlpInterceptorRoutines
00000000`0029f6d8  00000000`00000000
00000000`0029f6e0  00000000`00000860
00000000`0029f6e8  00000000`02270000
00000000`0029f6f0  00000000`02270000
00000000`0029f6f8  00000000`00000858
00000000`0029f700  00000000`00000000
00000000`0029f708  00000000`77b229ac ntdll!RtlAllocateHeap+0x16c
00000000`0029f710  00000000`02270000
00000000`0029f718  00000000`0000000a
00000000`0029f720  00000000`00000858
00000000`0029f728  00000000`00000860
00000000`0029f730  00000000`00000000
00000000`0029f738  00000000`0029f820
00000000`0029f740  00000000`77be7288 ntdll!RtlpInterceptorRoutines
00000000`0029f748  00000000`00000002
00000000`0029f750  00000000`00100030
00000000`0029f758  00000000`02270000
00000000`0029f760  00000000`0029f918
00000000`0029f768  00000000`00000020
00000000`0029f770  00000000`00000002
00000000`0029f778  00000000`00000005
00000000`0029f780  00000000`000750f0
00000000`0029f788  00000000`77ba25b2 ntdll!RtlpRegisterStackTrace+0x92
00000000`0029f790  00000000`000750b8
00000000`0029f798  00000000`00000003
00000000`0029f7a0  00000000`00000000
00000000`0029f7a8  00000000`77ad7a0a ntdll!RtlCaptureStackBackTrace+0x4a
00000000`0029f7b0  00000000`00000002
00000000`0029f7b8  00000000`00100030
00000000`0029f7c0  00000000`02270000
00000000`0029f7c8  00000000`03ce0040
00000000`0029f7d0  00000000`00100020
00000000`0029f7d8  00000000`77ba2eb7 ntdll!RtlpStackTraceDatabaseLogPrefix+0x57
00000000`0029f7e0  00000000`03ce0040
00000000`0029f7e8  00000000`00000000
00000000`0029f7f0  00000000`00100020
00000000`0029f7f8  00000000`000750f0
00000000`0029f800  00000000`77b6ed2d ntdll! ?? ::FNODOBFM::`string’+0×1a81b
00000000`0029f808  00000001`3faa1044 MemoryLeak_ProcessHeap!wmain+0×44
00000000`0029f810  00000001`3faa11ea MemoryLeak_ProcessHeap!__tmainCRTStartup+0×15a
00000000`0029f818  00000000`778cf56d kernel32!BaseThreadInitThunk+0xd
00000000`0029f820  00000000`77b03281 ntdll!RtlUserThreadStart+0×1d

00000000`0029f828  00000000`00000100
00000000`0029f830  00000000`00000000
00000000`0029f838  00000000`08001002
00000000`0029f840  00000000`08001002
00000000`0029f848  00000000`77b0fec9 ntdll!RtlCreateHeap+0×8f7
00000000`0029f850  00000000`02272000
00000000`0029f858  00000000`02270000
00000000`0029f860  00000000`02270000
00000000`0029f868  00000000`00000000
00000000`0029f870  03010301`00000000
00000000`0029f878  00000000`02270000
00000000`0029f880  00000000`02272000
00000000`0029f888  00000000`022f0000
00000000`0029f890  00000000`02270000
00000000`0029f898  02100301`00000000
00000000`0029f8a0  00000000`00001000
00000000`0029f8a8  00000000`77b9a886 ntdll!RtlpSetupExtendedBlock+0xc6
00000000`0029f8b0  00000000`00000000
00000000`0029f8b8  00000000`02272000
00000000`0029f8c0  00000000`000b0000
00000000`0029f8c8  03020302`00000230
00000000`0029f8d0  00000000`77be7288 ntdll!RtlpInterceptorRoutines
00000000`0029f8d8  00000000`00000002
00000000`0029f8e0  00000000`77be7288 ntdll!RtlpInterceptorRoutines
00000000`0029f8e8  00000000`00000002
00000000`0029f8f0  00000000`00100030
00000000`0029f8f8  00000000`02270000
00000000`0029f900  00000000`03ce0040
00000000`0029f908  00000000`77b6ed6a ntdll! ?? ::FNODOBFM::`string’+0×1a858
00000000`0029f910  00000000`00000000
00000000`0029f918  00000000`00000000
00000000`0029f920  00000000`00100000
00000000`0029f928  00000000`00101000
00000000`0029f930  00000000`00000020
00000000`0029f938  00000000`00000002
00000000`0029f940  00000000`00000000
00000000`0029f948  0000f569`df709780
00000000`0029f950  00000000`ffffffff
00000000`0029f958  00000000`12010013
00000000`0029f960  00000000`c00000bb
00000000`0029f968  00000000`00000000
00000000`0029f970  00000000`00000100
00000000`0029f978  000007fe`fdd91203 KERNELBASE!SleepEx+0xab
00000000`0029f980  00000000`0029fa38
00000000`0029f988  00000000`00000000
00000000`0029f990  00000000`00000000
00000000`0029f998  00000000`00000012
00000000`0029f9a0  ffffffff`ff676980
00000000`0029f9a8  00000000`0029f9a0
00000000`0029f9b0  00000000`00000048
00000000`0029f9b8  00000000`00000001
00000000`0029f9c0  00000000`00000000
00000000`0029f9c8  00000000`00000000
00000000`0029f9d0  00000000`00000000
00000000`0029f9d8  00000000`00000000
00000000`0029f9e0  00000000`00000000
00000000`0029f9e8  00000000`00000000
00000000`0029f9f0  00000000`00000000
00000000`0029f9f8  00000000`00000000
00000000`0029fa00  00000000`00000000
00000000`0029fa08  00000000`00000001
00000000`0029fa10  00000000`00000000
00000000`0029fa18  00000001`3faa104f MemoryLeak_ProcessHeap!wmain+0×4f
00000000`0029fa20  00000000`02270000

Now we see this stack trace fragment from user mode stack trace database on the raw stack shown above:

00000000`0029f800  00000000`77b6ed2d ntdll! ?? ::FNODOBFM::`string'+0x1a81b
00000000`0029f808  00000001`3faa1044MemoryLeak_ProcessHeap!wmain+0×44
00000000`0029f810  00000001`3faa11ea MemoryLeak_ProcessHeap!__tmainCRTStartup+0×15a
00000000`0029f818  00000000`778cf56d kernel32!BaseThreadInitThunk+0xd
00000000`0029f820  00000000`77b03281 ntdll!RtlUserThreadStart+0×1d

And it looks like HeapAlloc was called from wmain indeed with 0×100000 parameter:

0:000> ub 00000001`3faa1044
MemoryLeak_ProcessHeap!wmain+0x26:
00000001`3faa1026 xor     edx,edx
00000001`3faa1028 xor     ecx,ecx
00000001`3faa102a call    qword ptr [MemoryLeak_ProcessHeap!_imp_HeapCreate (00000001`3faa7000)]
00000001`3faa1030 mov     rbx,rax
00000001`3faa1033 xor     edx,edx
00000001`3faa1035 mov     r8d,100000h
00000001`3faa103b mov     rcx,rbx
00000001`3faa103e call    qword ptr [MemoryLeak_ProcessHeap!_imp_HeapAlloc (00000001`3faa7008)]

0:000> dps 00000001`3faa7008 L1
00000001`3faa7008  00000000`77b21b70 ntdll!RtlAllocateHeap

The stack trace fragment from x86 Vista user dump even more straightforward:

0040fa00 77946e0c ntdll!RtlAllocateHeap+0×1e3
0040fa04 0022103a MemoryLeak_ProcessHeap!wmain+0×3a

0040fa08 7677d0e9 kernel32!BaseThreadInitThunk+0xe
0040fa0c 779219bb ntdll!__RtlUserThreadStart+0×23
0040fa10 7792198e ntdll!_RtlUserThreadStart+0×1b
0040fa14 7798924f ntdll!RtlpLogCapturedStackTrace+0×103

Of course, we could simply disassemble wmain after identifying our thread but in real life functions are longer and leaking allocations could have happened from frames not present on current stack traces.

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

Ontological and Epistemological Memoidealism

Saturday, May 22nd, 2010

Just want to clarify the following branches of memoidealism (memory idealism) in addition to its common sense pragmatic panmemoric version:

Ontological memoidealism

The ultimate nature of reality is based on the memory

Epistemological memoidealism

The only things that can be directly known are memories

Another question often asked is why memory idealism and not memory realism. I have chosen the former because memory is often closely associated with the mind. In many cases you can just replace mind with memory, for example:

… science is in reality a classification and analysis of the contents of the memory;1)

We choose the most important property of the mind and computers: memory and try to ground and explain reality and mind in terms of that ontologically elevated property.

1) Karl Pearson, The Grammar of Science

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

Bugtation No.120

Saturday, May 22nd, 2010

… science is in reality a classification and analysis of the contents of the memory;

Karl Pearson, The Grammar of Science

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

Psychoanalysis of Software Troubleshooting and Debugging (Part 1)

Friday, May 21st, 2010

In this part I would like to introduce the notion of Forgotten Facts in opposition to Basic Facts or supporting information. These are facts that engineers often feel uncomfortable to mention because they are troubleshooting information they couldn’t obtain (if they tried) due to some time or customer pressures, failures, incorrectly understood troubleshooting procedures or some other obstacles. Therefore it is important to have a set of counter questions or checklists mapped from common software behaviour patterns to software troubleshooting patterns. Problem descriptions should also be subjected to close reading to reveal unconsciously concealed information. Next part will explore this in more detail with some case studies commissioned by Software Maintenance Institute.

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

Two Readings of a Software Trace

Friday, May 21st, 2010

When we have a software trace we read it in two directions. The first one is to deconstruct it into a linear ordered source code based on PLOT fragments. The second direction is to construct an interpretation that serve as an explanation for reported software behaviour. During the interpretive reading we remove irrelevant information, compress relevant activity regions and construct the new fictional software trace based on discovered patterns and our problem description.

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

Icons for Memory Dump Analysis Patterns (Part 42)

Wednesday, May 19th, 2010

Today we introduce an icon for Double Free (kernel pool) pattern:

B/W

Color

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

Icons for Memory Dump Analysis Patterns (Part 41)

Tuesday, May 18th, 2010

Today we introduce an icon for Double Free (process heap) pattern:

B/W

Color

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

Icons for Memory Dump Analysis Patterns (Part 40)

Monday, May 17th, 2010

Today we introduce an icon for Unknown Component pattern:

B/W

Color

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

Dr. DebugLove and Nature

Sunday, May 16th, 2010

Pictures taken today during weekend nature walks (debugging walkthroughs) in Dublin suburbs:

Before A Debugging Session

Looking For Bugs

Found A Bug

Looking For More Bugs

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

MDAA Volumes are Asm Bestsellers

Sunday, May 16th, 2010

Just noticed a rare event when all three volumes of Memory Dump Analysis Anthology occupy the first 3 positions on Bestsellers in Assembly Language Programming Amazon list (observed at the time of this writing):

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

Models for Memory and Trace Analysis Patterns (Part 1)

Sunday, May 16th, 2010

Due to many requests for memory dumps corresponding to crash dump analysis patterns I’ve started modeling software behaviour and defects. Every pattern will have an example application(s), service(s) or driver(s) or combination of them. Their execution results in memory layout that corresponds to memory or trace analysis patterns. Today we introduce an example model for Multiple Exceptions (user mode) pattern. The following source code models 3 threads each having an exception during their execution on Windows XP, Windows 7 and Windows Server 2008 R2:

// MultipleExceptions-UserMode
// Copyright (c) 2010 Dmitry Vostokov
// GNU GENERAL PUBLIC LICENSE
// http://www.gnu.org/licenses/gpl-3.0.txt

#include <windows.h>
#include <process.h>

void thread_one(void *)
{
 *(int *)NULL = 0;
}

void thread_two(void *)
{
 *(int *)NULL = 0;
}

int main(int argc, WCHAR* argv[])
{
 _beginthread(thread_two, 0, NULL);
 _beginthread(thread_one, 0, NULL);

 DebugBreak();

 return 0;
}

In fact, thread_one and thread_two can be replaced with just one function because they are identical. Visual C++ compiler does that during code optimization. On Windows 7 and W2K8 R2 I created LocalDumps registry key to save full crash dumps. On Windows XP I set Dr. Watson as a postmortem debugger (via drwtsn32 -i command and configured it to save full user dumps via drwtsn32 command that brings Dr. Watson GUI). Vista had some peculiar behaviour so I postponed its discussion for another post. The application can be downloaded from here (zip file contains source code, x86 and x64 binaries together with corresponding PDB files):

Download MultipleExceptions-UserMode.zip

Now I provide modeling results for x64 W2K8 R2 running on 2 processor machine. Windows 7 and Windows XP results are very similar. If we run x64 executable it crashes and a dump file is saved (x86 crash dump is similar). Default analysis command gives these results:

0:000> !analyze -v

[...]

FAULTING_IP:
MultipleExceptions_UserMode!thread_two+0
00000001`3f8b1000 c704250000000000000000 mov dword ptr [0],0

EXCEPTION_RECORD:  ffffffffffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 000007fefddc2442 (KERNELBASE!DebugBreak+0x0000000000000002)
   ExceptionCode: 80000003 (Break instruction exception)
  ExceptionFlags: 00000000
NumberParameters: 1
   Parameter[0]: 0000000000000000

[...]

ERROR_CODE: (NTSTATUS) 0x80000003 - {EXCEPTION}  Breakpoint  A breakpoint has been reached.

[...]

PRIMARY_PROBLEM_CLASS:  STATUS_BREAKPOINT

[...]

STACK_TEXT: 
00000001`3f8b1000 MultipleExceptions_UserMode!thread_two+0x0
00000001`3f8b10eb MultipleExceptions_UserMode!_callthreadstart+0x17
00000001`3f8b1195 MultipleExceptions_UserMode!_threadstart+0x95
00000000`778cf56d kernel32!BaseThreadInitThunk+0xd
00000000`77b03281 ntdll!RtlUserThreadStart+0x1d

[...]

We see debug break on the first thread:

0:000> kL
Child-SP          RetAddr           Call Site
00000000`002eec78 000007fe`fdd913a6 ntdll!NtWaitForMultipleObjects+0xa
00000000`002eec80 00000000`778d3143 KERNELBASE!WaitForMultipleObjectsEx+0xe8
00000000`002eed80 00000000`77949025 kernel32!WaitForMultipleObjectsExImplementation+0xb3
00000000`002eee10 00000000`779491a7 kernel32!WerpReportFaultInternal+0x215
00000000`002eeeb0 00000000`779491ff kernel32!WerpReportFault+0x77
00000000`002eeee0 00000000`7794941c kernel32!BasepReportFault+0x1f
00000000`002eef10 00000000`77b6573c kernel32!UnhandledExceptionFilter+0x1fc
00000000`002eeff0 00000000`77ae5148 ntdll! ?? ::FNODOBFM::`string'+0x2365
00000000`002ef020 00000000`77b0554d ntdll!_C_specific_handler+0x8c
00000000`002ef090 00000000`77ae5d1c ntdll!RtlpExecuteHandlerForException+0xd
00000000`002ef0c0 00000000`77b1fe48 ntdll!RtlDispatchException+0x3cb
00000000`002ef7a0 000007fe`fddc2442 ntdll!KiUserExceptionDispatcher+0x2e
00000000`002efd58 00000001`3f8b103c KERNELBASE!DebugBreak+0×2
00000000`002efd60 00000001`3f8b13fb MultipleExceptions_UserMode!main+0×2c
00000000`002efd90 00000000`778cf56d MultipleExceptions_UserMode!__tmainCRTStartup+0×15b
00000000`002efdd0 00000000`77b03281 kernel32!BaseThreadInitThunk+0xd
00000000`002efe00 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

2 other threads show exception processing too:

0:000> ~1s; kL
ntdll!NtDelayExecution+0xa:
00000000`77b201fa c3              ret
Child-SP          RetAddr           Call Site
00000000`0076ef78 000007fe`fdd91203 ntdll!NtDelayExecution+0xa
00000000`0076ef80 00000000`77949175 KERNELBASE!SleepEx+0xab
00000000`0076f020 00000000`779491ff kernel32!WerpReportFault+0×45
00000000`0076f050 00000000`7794941c kernel32!BasepReportFault+0×1f
00000000`0076f080 00000000`77b6573c kernel32!UnhandledExceptionFilter+0×1fc
00000000`0076f160 00000000`77ae5148 ntdll! ?? ::FNODOBFM::`string’+0×2365
00000000`0076f190 00000000`77b0554d ntdll!_C_specific_handler+0×8c
00000000`0076f200 00000000`77ae5d1c ntdll!RtlpExecuteHandlerForException+0xd
00000000`0076f230 00000000`77b1fe48 ntdll!RtlDispatchException+0×3cb
00000000`0076f910 00000001`3f8b1000 ntdll!KiUserExceptionDispatcher+0×2e

00000000`0076fec8 00000001`3f8b10eb MultipleExceptions_UserMode!thread_two
00000000`0076fed0 00000001`3f8b1195 MultipleExceptions_UserMode!_callthreadstart+0×17
00000000`0076ff00 00000000`778cf56d MultipleExceptions_UserMode!_threadstart+0×95
00000000`0076ff30 00000000`77b03281 kernel32!BaseThreadInitThunk+0xd
00000000`0076ff60 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

0:001> ~2s; kL
ntdll!NtDelayExecution+0xa:
00000000`77b201fa c3              ret
Child-SP          RetAddr           Call Site
00000000`0086e968 000007fe`fdd91203 ntdll!NtDelayExecution+0xa
00000000`0086e970 00000000`77949175 KERNELBASE!SleepEx+0xab
00000000`0086ea10 00000000`779491ff kernel32!WerpReportFault+0×45
00000000`0086ea40 00000000`7794941c kernel32!BasepReportFault+0×1f
00000000`0086ea70 00000000`77b6573c kernel32!UnhandledExceptionFilter+0×1fc
00000000`0086eb50 00000000`77ae5148 ntdll! ?? ::FNODOBFM::`string’+0×2365
00000000`0086eb80 00000000`77b0554d ntdll!_C_specific_handler+0×8c
00000000`0086ebf0 00000000`77ae5d1c ntdll!RtlpExecuteHandlerForException+0xd
00000000`0086ec20 00000000`77b1fe48 ntdll!RtlDispatchException+0×3cb
00000000`0086f300 00000001`3f8b1000 ntdll!KiUserExceptionDispatcher+0×2e

00000000`0086f8b8 00000001`3f8b10eb MultipleExceptions_UserMode!thread_two
00000000`0086f8c0 00000001`3f8b1195 MultipleExceptions_UserMode!_callthreadstart+0×17
00000000`0086f8f0 00000000`778cf56d MultipleExceptions_UserMode!_threadstart+0×95
00000000`0086f920 00000000`77b03281 kernel32!BaseThreadInitThunk+0xd
00000000`0086f950 00000000`00000000 ntdll!RtlUserThreadStart+0×1d

We look at unhandled exception filter parameter to get exception pointers information:

0:002> kv
Child-SP          RetAddr           : Args to Child                                                           : Call Site
[...]
00000000`0086ea70 00000000`77b6573c : 00000000`0086ebb0 00000000`00000006 00000001`00000000 00000000`00000001 : kernel32!UnhandledExceptionFilter+0×1fc

0:002> .exptr 00000000`0086ebb0

----- Exception record at 00000000`0086f7f0:
ExceptionAddress: 000000013f8b1000 (MultipleExceptions_UserMode!thread_two)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 0000000000000001
   Parameter[1]: 0000000000000000
Attempt to write to address 0000000000000000

----- Context record at 00000000`0086f300:
rax=00000000000ef0b0 rbx=00000000000ef0b0 rcx=0000000000000000
rdx=0000000000000000 rsi=0000000000000000 rdi=0000000000000000
rip=000000013f8b1000 rsp=000000000086f8b8 rbp=0000000000000000
 r8=000007fffffda000  r9=0000000000000000 r10=0000000000000045
r11=000007fffffd9328 r12=0000000000000000 r13=0000000000000000
r14=0000000000000000 r15=0000000000000000
iopl=0         nv up ei pl nz na pe nc
cs=0033  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010202
MultipleExceptions_UserMode!thread_two:
00000001`3f8b1000 c704250000000000000000 mov dword ptr [0],0 ds:00000000`00000000=????????

What we now see that default analysis command showed the break instruction exception record and error code from the first thread but IP and stack trace from other threads having NULL pointer access violation exception.

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