Vector35 / Vector35/binaryninja-api

Floating point type propagation failure

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Component: Core Core: MLIL Effort: Trivial Impact: Medium
Dominant language
C++
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Description

MLIL fails to properly propagate a floating point type to the constant under some conditions.

In the included binary you can see that on instruction 0x0000298f the constant isn't being represented as a floating point value and the zmm0 variable doesn't have the type of double

image

It should be trivially determinable via the following instruction indicating its part of a floating point add
image

fp_bug.zip

Special Thanks to: Zao Yang and Stefan Nagy for their research in Decompiler Fuzzing for reporting this issue.

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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 with the attached fp_bug.zip and inspect MLIL at instruction 0x0000298f, comparing the constant and zmm0 types with the following floating-point add instruction. Done means the included binary propagates the floating-point and double types correctly at that location.

Written by the indexing model from the issue text.

Assessment

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

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