Archive for August, 2008

Bugtation No.9

Wednesday, August 20th, 2008

“There is nothing more deceptive than an obvious” bug.

Sherlock Holmes, The Boscombe Valley Mystery

- Dmitry Vostokov @ DumpAnalysis.org -

Gossip about Dr. Debugalov

Wednesday, August 20th, 2008

New cartoon from Narasimha Vedala (click on it to enlarge):

Misty morning gossip in the park

DBG_Gossipinthepark from Narasimha Vedala (click to enlarge)

- Dmitry Vostokov @ DumpAnalysis.org -

ManagementBits update (June - August, 2008)

Tuesday, August 19th, 2008

I wasn’t active last 3 months although I have many cached managerial thoughts in my Moleskine notebook that I plan to start publishing in September.

ManagementBits Blog:

Expectations, expectations…

Management Bit and Tip 0×800

I don’t remember whether I told this before or not but all management bits are available in a handy bit string here:

Management Bit String

- Dmitry Vostokov @ DumpAnalysis.org -

The Psychology and Psychiatry of Bugs

Tuesday, August 19th, 2008

New cartoon from Narasimha Vedala provides insight into crazy bugs (click on it to enlarge):

A visit to the Psychiatrist

DBG_Psychiatrist from Narasimha Vedala (click to enlarge)

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.8

Tuesday, August 19th, 2008

Debugging “will one day be as necessary for efficient” programming “as the ability to read and write” code.

Herbert George Wells

- Dmitry Vostokov @ DumpAnalysis.org -

Life cycle of a bug

Tuesday, August 19th, 2008

New cartoon from Narasimha Vedala provides insight into the beauty of nature (click on it to enlarge):

Nature’s Wonder: Life cycle of a beetle

DBG_LifeCycleOfBug from Narasimha Vedala (click to enlarge)

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.7

Monday, August 18th, 2008

This bugtation is identical to the original quotation:

“Thank you for not dividing by zero.”

Unknown

Encouraged by this I propose another one :-)

“Thank you for checking for NULL pointers.”

Dmitry Vostokov

- Dmitry Vostokov @ DumpAnalysis.org -

Beijing Bytes report

Monday, August 18th, 2008

New cartoon from Narasimha Vedala captures recent rumors about the opening of Olympics:

DBG_BeijingBytes from Narasimha Vedala

Just to remind you that China is 6th on my Memory Dump Awareness Index.

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.6

Monday, August 18th, 2008

“I admit that” debugging “is a good thing. But excessive devotion to it is a bad thing.”

Aldous Leonard Huxley

- Dmitry Vostokov @ DumpAnalysis.org -

LiterateScientist update (June - August, 2008)

Monday, August 18th, 2008

There were no updates last two months primarily because I was still reading huge books 1,000 pages each. One of them was The Road to Reality that I started in March and finished only a few weeks ago. When I was about two-thirds through it and I thought that I could never finish it a sign happened to shed the light on the possible end. While commuting from work a shadow from the train window sign projected ”Exit” on the book and I asked  to take a picture of this event:

LiterateScientist Blog:

Under Pressure

Breaking the Spell

Darwin’s Dangerous Idea

The Skeptical Environmentalist

Ideas and Modern Mind 

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.5

Sunday, August 17th, 2008

“The great tragedy of” Software: “the slaying of a beautiful” program “by an ugly” bug.

Thomas Henry Huxley, Collected Essays

- Dmitry Vostokov @ DumpAnalysis.org -

WinDbg shortcuts: .sound_notify

Saturday, August 16th, 2008

Suppose we set up breakpoints to catch a random issue or at the end of a lengthy loop and we don’t want to sit tight, stare at the screen and wait for a debugger notification event. We just want to sit relaxed and read our favourite book or do something else. I discovered this meta-command where we can specify a wave file to be played every time a debugger breaks into a command prompt:

The .sound_notify command causes a sound to be played when WinDbg enters the wait-for-command state (from WinDbg help).

For example:

(15dc.dd0): Break instruction exception - code 80000003 (first chance)
eax=7ffde000 ebx=00000000 ecx=00000000 edx=77b3d094 esi=00000000 edi=00000000
eip=77af7dfe esp=01c6fbf4 ebp=01c6fc20 iopl=0 nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246
ntdll!DbgBreakPoint:
77af7dfe cc              int     3

windbg> .sound_notify /ef c:\Windows\Media\tada.wav
Sound notification: file 'c:\Windows\Media\tada.wav'

0:001> g
(15dc.175c): Break instruction exception - code 80000003 (first chance)
eax=7ffde000 ebx=00000000 ecx=00000000 edx=77b3d094 esi=00000000 edi=00000000
eip=77af7dfe esp=01cafc08 ebp=01cafc34 iopl=0 nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246
ntdll!DbgBreakPoint:
77af7dfe cc              int     3

[tada.wav is played when we break into]

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.4

Saturday, August 16th, 2008

“O” engineers, “throw light on this error.”

Leonardo da Vinci, The Notebooks

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.3

Friday, August 15th, 2008

“If you find the” crash dump, “perhaps others may find the explanation.”

Sherlock Holmes, The Problem of Thor Bridge

- Dmitry Vostokov @ DumpAnalysis.org -

All at once: postmortem logs and dump files

Friday, August 15th, 2008

In the previous post about resolving security issues with crash dumps I mentioned the solution to use logs generated from memory dump files. In the case of process dumps the obvious step is to save logs by a postmortem debugger at the moment of the crash. Here WinDbg scripts come to the rescue. Suppose that CDB is set as a postmortem debugger (see Custom postmortem debuggers on Vista) and AeDebug \ Debugger registry key value is set to:

"C:\Program Files\Debugging Tools for Windows\cdb.exe" -p %ld -e %ld -g -y SRV*c:\mss*http://msdl.microsoft.com/download/symbols -c "$$><c:\WinDbgScripts\LogsAndDumps.txt;q"

Here we specify MS symbols server and the script file. The symbol path is absolutely necessary to have correct stack traces. The script file has the following contents: 

.logopen /t c:\UserDumps\process.log
.kframes 100
!analyze -v
~*kv
lmv
.logclose
.dump /m /u c:\UserDumps\mini_process
.dump /ma /u c:\UserDumps\full_process
.dump /mrR /u c:\UserDumps\secure_mini_process
.dump /marR /u c:\UserDumps\secure_full_process

.kframes WinDbg meta-command is necessary to avoid the common pitfall of looking at cut off stack traces (see Mistake #1). In addition to logging the output of any command we want, the script writes 4 memory dumps of the same process:

- mini dump
- full dump
- secure mini dump
- secure full dump

My previous post WinDbg is privacy-aware explains secure dumps in detail. If you need to tailor dump file names and logs to include real process name might need to try the following or similar technique explained here:

Generating file name for .dump command

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.2

Thursday, August 14th, 2008

“It requires a very unusual mind to undertake the analysis of the obvious” crash.

Alfred North Whitehead, Science and the Modern World

- Dmitry Vostokov @ DumpAnalysis.org -

Bugtation No.1

Wednesday, August 13th, 2008

First, a definition for a new word that I coined today:  

Bugtation

noun
Date: 21st century
1. a modified quotation showing relation to debugging and troubleshooting

This is the first bugtation I would like to introduce and it is related to heisenbugs:

“There’s no such thing as” heisenbug;
“And what to us seems merest accident
Springs from the deepest source of” computation.

Friedrich Schiller, Early Dramas 

Deviations from original quotations are highlighted in blue. Welcome to the new literary art! :-)

Note: if you notice any bugs in bugtations please let me know…

- Dmitry Vostokov @ DumpAnalysis.org -

Generating file name for .dump command

Wednesday, August 13th, 2008

.dump WinDbg command doesn’t have an option to include the process name although we can specify PID, date and time using /u option. This question came to me ages ago but only yesterday one of the visitors (Thomas B.) provided a hint to use aliases:

as /c CrashApp [get a module name here]

.dump /ma /u c:\UserDumps\${CrashApp}.dmp

Unfortunately an attempt to use lm command fails due to a line break in the output:

0:001> lmM *.exe 1m
notepad

0:001> as /c CrashApp lmM *.exe 1m

0:001> .dump /ma /u c:\UserDumps\${CrashApp}.dmp
Unable to create file 'c:\UserDumps\notepad
_06ec_2008-08-13_14-39-30-218_06cc.dmp
‘ - Win32 error 0n123
    “The filename, directory name, or volume label syntax is incorrect.”

After some thinking I recalled that .printf command doesn’t output line breaks. Also the module name can be extracted from _PEB structure if it is accessible. $peb pseudo-register can be used to get PEB address automatically. Therefore I came up with the following alias:

as /c CrashFirstModule .printf "%mu", @@c++((*(ntdll!_LDR_DATA_TABLE_ENTRY**)&@$peb->Ldr->InLoadOrderModuleList.Flink)->BaseDllName.Buffer)

0:001> as /c CrashFirstModule .printf "%mu", @@c++((*(ntdll!_LDR_DATA_TABLE_ENTRY**)&@$peb->Ldr->InLoadOrderModuleList.Flink)->BaseDllName.Buffer)

0:001> .dump /ma /u c:\UserDumps\${CrashFirstModule}.dmp
Creating c:\UserDumps\notepad.exe_06ec_2008-08-13_14-44-51-702_06cc.dmp - mini user dump
Dump successfully written

These commands can be included in a script for a postmortem debugger, for example, CDB.

- Dmitry Vostokov @ DumpAnalysis.org -

MDAA Volume 2 is coming out soon

Tuesday, August 12th, 2008

Yesterday I sent to print the first draft version with finalized covers for editing in situ. I usually do editing on the real book. Then error corrections and layout improvements can be done in real WYSIWYG hardcopy book mode. What’s new in Volume 2:

- 45 new crash dump analysis patterns
- Pattern interaction and case studies
- Updated checklist
- Fully cross-referenced with Volume 1
- New appendixes

I aim to publish paperback and digital versions on the 3st of October and hardcover version on the 1st of November. Table of Contents will be announced in soon.

Here’s the book cover:

Back cover features visualized virtual process memory generated from a memory dump of colorimetric computer memory dating sample using Dump2Picture.

- Dmitry Vostokov @ DumpAnalysis.org -

Sherlock Holmes calls Dr. Debugalov

Tuesday, August 12th, 2008

New cartoon from Narasimha Vedala:

Sherlock Holmes ponders…

DBG_SherlockPonders from Narasimha Vedala

- Dmitry Vostokov @ DumpAnalysis.org -