Vector35 / Vector35/binaryninja-api
Overly broadly PVS due to opaque branch not removed at MLIL
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- C++
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Description
In the following code, arg_8 reports a PVS of {0x7f5b, 0x7f5c}:
It might be confusing since reading the HLIL, it appears the value should be just {0x7f5c}. As it turns out, this is caused by an opaque branch at MLIL (instruction 13):
Since we are doing PVS calculation at MLIL, and this opaque branch is not removed at MLIL, thus we retain the 0x7f5b value for its PVS
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Inspect the MLIL around instruction 13 and compare its opaque branch with the corresponding HLIL and PVS result described in the report. Trace the MLIL PVS calculation to determine why 0x7f5b is retained; done means the reported arg_8 PVS matches the HLIL-visible value of 0x7f5c.
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
- Mostly clear
- Newbie friendliness
- 38/100