Crash Dump Analysis Patterns (Part 135)

Module Hint pattern is frequently observed in dynamic memory corruption incidents. It is similar to Execution Residue or String Parameter patterns were we have ASCII or UNICODE fragments providing troubleshooting and debugging hints. Module Hint is therefore a more specialized pattern where we can link module names to raw data. For example, a kernel memory dump saved after the detected pool corruption shows P12345.DLL module name in a pool entry that can provide a link to the corresponding functionally to be reconfigured or removed:

The pool is already corrupt at the time of the current request.
This may or may not be due to the caller.
The internal pool links must be walked to figure out a possible cause of the problem, and then special pool applied to the suspect tags or the driver verifier to a suspect driver.
Arg1: 00000020, a pool block header size is corrupt.
Arg2: 8b79d078, The pool entry we were looking for within the page.
Arg3: 8b79d158, The next pool entry.
Arg4: 8a1c0004, (reserved)

b3e0aa4c 808947bb 00000019 00000020 8b79d078 nt!KeBugCheckEx+0x1b
b3e0aab4 b368c00f 8b79d080 00000000 00000000 nt!ExFreePoolWithTag+0×477
b3e0aac4 b366c68e 8b79d080 00000000 00000000 DriverA!MemFree+0xf
b3e0ac44 8081e0c3 808f77c9 b3e0ac64 808f77c9 nt!IovCallDriver+0×112
b3e0ac50 808f77c9 8a8eef60 8b6862a8 8a8eeef0 nt!IofCallDriver+0×13
b3e0ac64 808f856b 8ce456b0 8a8eeef0 8b6862a8 nt!IopSynchronousServiceTail+0×10b
b3e0ad00 808f109a 000009dc 00000000 00000000 nt!IopXxxControlFile+0×5e5
b3e0ad34 8088b45c 000009dc 00000000 00000000 nt!NtDeviceIoControlFile+0×2a
b3e0ad34 7c82847c 000009dc 00000000 00000000 nt!KiFastCallEntry+0xfc
WARNING: Frame IP not in any known module. Following frames may be wrong.
00f5fb18 00000000 00000000 00000000 00000000 0×7c82847c

2: kd> !pool 8b79d080
Pool page 8b79d080 region is Unknown
 8b79d000 size:   30 previous size:    0  (Allocated)  FSfm
 8b79d030 size:   28 previous size:   30  (Allocated)  VadS
 8b79d058 size:   20 previous size:   28  (Allocated)  ReEv
*8b79d078 size:   e0 previous size:   20  (Allocated) *DRIV 
  Owning component : Unknown (update pooltag.txt)
8b79d158 is not a valid large pool allocation, checking large session pool…
8b79d158 is freed (or corrupt) pool
Bad previous allocation size @8b79d158, last size was 1c

*** An error (or corruption) in the pool was detected;
*** Pool Region unknown (0xFFFFFFFF8B79D158)
*** Use !poolval 8b79d000 for more details.

2: kd> dc 8b79d078
8b79d078  [...] ..DRIV  ......AP
8b79d088  [...] P12345.DLL……
8b79d098  […] …..<%n……..
8b79d0a8  […] ….$…:.F…X.

- Dmitry Vostokov @ + -

3 Responses to “Crash Dump Analysis Patterns (Part 135)”

  1. Dmitry Vostokov Says:

    Another example is the presence of debugging or error handling modules in module list

  2. Dmitry Vostokov Says:

    It can also be a valid (non-coincidental, see Coincidental Symbolic Information analysis pattern) symbolic name via dps or dpS command.

  3. Dmitry Vostokov Says:

    We can also use search commands s-sa and s-su

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