The ba command (Break on Access) in WinDbg is not working as advertised in the book Advanced Windows Debugging by Daniel Pravat and Mario Hewardt - windbg

Question

I am reading the book Advanced Windows Debugging: Developing and Administering Reliable, Robust, and Secure Software by Daniel Pravat and Mario Hewardt. I have questions about Chapter 2.
I am using WinDBG 10.0.19041.1 X86 on Windows 10 Pro Version 2004 build 19041.572. I built 02sample.exe with Microsoft Visual Studio Community 2019 Version 16.7.6 with the GenerateDebugInformation property set to DebugFull. I am debugging the Debug|x86 configuration of 02sample.exe.
I am reading the section in chapter 2 named Setting a Breakpoint on Access and I am seeing differences between what is in the book and what I am experiencing.
The first difference in behavior is with the following command.
0:000> dt gGlobal
This command fails with the following error.
Symbol gGlobal not found.
The following command does work.
0:000> dt 02sample!gGlobal
*** WARNING: Unable to verify checksum for 02sample.exe
gGlobal
+0x000 m_ref : 0n0
The next difference in behavior is with the following command.
0:000> ba w4 gGlobal+0
Based on the following output, this appears to work.
0:000> bl
0 e Disable Clear 00969130 w 4 0001 (0001) 0:**** 02sample!gGlobal
However, the breakpoint is not being hit. I cannot figure out why.

Answer 1

Symbols Are probably Not Yet Loaded
try either .reload /f or .reload /f foo.exe
before attempting unqualified dt gGlobal
a qualified foo!gGlobal will always work because it loads the symbols
check with !sym noisy
0:000> !sym noisy
noisy mode - symbol prompts off
0:000> dt gGlobal
Symbol gGlobal not found.
0:000> dt gGlobal
Symbol gGlobal not found.
0:000> dt gGlobal
Symbol gGlobal not found.
0:000> dt awd!gGlobal
SYMSRV: BYINDEX: 0x2
snipxxxxxxxxxxxxxxx
DBGHELP: awd - public symbols & lines
C:\Users\XXX\Desktop\awd\Chapter2\Debug\awd.pdb
+0x000 m_ref : 0n0
0:000>
how is the Book Telling You to set the ba breakpoint ?
You Cannot Set a ba breakpoint on a module when you are Stopped At System Breakpoint
Because the system will reset the thread context
you have to go the Entry Point and then Set the ba breakpoint as windbg suggests do you do that ?
:\>cdb -c "g #$exentry;ba w4 awd!gGlobal;g;u .;kb;q" awd.exe |awk "/Reading/,/quit/"
0:000> cdb: Reading initial command 'g #$exentry;ba w4 awd!gGlobal;g;u .;kb;q'
*** WARNING: Unable to verify checksum for awd.exe
Breakpoint 0 hit
awd!Global::Global+0x21:
00a23461 8b45fc mov eax,dword ptr [ebp-4]
00a23464 83c404 add esp,4
00a23467 3bec cmp ebp,esp
00a23469 e895ddffff call awd!ILT+510(__RTC_CheckEsp) (00a21203)
00a2346e 8be5 mov esp,ebp
00a23470 5d pop ebp
00a23471 c3 ret
00a23472 cc int 3
ChildEBP RetAddr Args to Child
0026f9d4 00a21687 0026f9ec 522c59df 00a21670 awd!Global::Global+0x21
0026f9dc 522c59df 00a21670 00a2b208 0026fa50 awd!`dynamic initializer for 'gGlobal''+0x17
0026f9ec 00a24a5e 00a2b000 00a2b30c 91b61bad ucrtbased!_initterm+0x3f
0026fa50 00a2498d 0026fa60 00a24d08 0026fa6c awd!__scrt_common_main_seh+0xbe
0026fa58 00a24d08 0026fa6c 7683ed6c 7ffde000 awd!__scrt_common_main+0xd
0026fa60 7683ed6c 7ffde000 0026faac 773337eb awd!wmainCRTStartup+0x8
0026fa6c 773337eb 7ffde000 761f96f6 00000000 kernel32!BaseThreadInitThunk+0xe
0026faac 773337be 00a21145 7ffde000 00000000 ntdll!__RtlUserThreadStart+0x70
0026fac4 00000000 00a21145 7ffde000 00000000 ntdll!_RtlUserThreadStart+0x1b
quit:
if by chance you misunderstood entrypoint to wmain() and set a ba break on reaching wmain() it probably will never be hit because the code in question has already been executed