Vector35 / Vector35/binaryninja-api

`__chkstk` screws up stack pointer analysis

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#5,781 4 comments 4 reactions 0 assignees View on GitHub

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Component: Core Effort: Medium Impact: Low
Dominant language
C++
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Merged PRs (30d)
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Description

Screenshot 2024-07-20 at 12 52 56 PM

In the screenshot, we see that rsp becomes a variable due to the __chkstk call:

BEDaisy.sys.zip

If we patch and remove the code the stack variables are correctly analyzed:

Screenshot 2024-07-20 at 12 54 22 PM

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the report with the attached BEDaisy.sys.zip and inspect the stack-pointer analysis around the __chkstk call. Compare the result with the patched version shown in the screenshots; done means rsp is analyzed correctly and stack variables are recovered without removing the call.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
reverse-engineering
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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