[llvm-dev] LLVM Call Graph may not cover all calls

[cszide via llvm-dev]

Hi Chaz,
Thanks for your suggestions. But, as the tool's name, 'OverCG', the call graph may be over-approximation， and I only test it for c code.
Maybe I will implement a plugin using c++, I currently am learning how to use llvm:)
If you have any suggestions, please let me know. Thank you!

The CFG is right. Currently, the developers of opt/llvm only consider the direct call made by the call instruction, since the different language (rust, julia ...) has different calling convention.


Best,
Zhide






At 2018-11-19 10:49:15, "changze cui" <changzecui at gmail.com> wrote:

Hi zhide,
  Cool Bro!!!!!!
  Your tool solve my problem perfectly !!!
  It seems the original call graph has some problems. Then why don't you submit your solution to LLVM-dev and integrate your code into the next version of opt? Your code may help lots of people like me who is not very familiar with LLVM.
  BTW, probably CFG has the same problem because I think call graph is generated from CFG. Did you check before?
  Anyway, Thanks a lot !!


Regards,
Chaz


cszide <cszide at 163.com> 于2018年11月17日周六 上午9:38写道：

Hi, 
I also have the same problem and I wrote some codes to mitigate this problem.
You can find it on github https://github.com/coffezhou/OverCG. I try it on the IR you 
provided and it can get the call relationship from fsdither ->  TIFFWriteScanLine.
I hope it can help you.


Best,
Zhide






At 2018-11-09 00:44:18, "changze cui via llvm-dev" <llvm-dev at lists.llvm.org> wrote:

Hi there,
   I am working with opt-6.0 and try to generate a call graph of libsndfile, but it seems the call graph doesn't cover all call relationship.
   Actually, I am doing static analysis on CVE-2014-8130, which is a zero division on libtiff/tif_write.c  TIFFWriteScanline.   (see https://security-tracker.debian.org/tracker/CVE-2014-8130)
   Theoretically, the main function in tiffdither.c will call fsdither, and fsdither will call TIFFWriteScanLine.   main (tiffdither.c) -> fsdither (tiffdither.c) -> TIFFWriteScanLine (tif_write.c)
   I want to get a call graph of the buggy program tiffdither but I find the call graph generated doesn't cover the call relationship from fsdither ->  TIFFWriteScanLine.
   For short, the call graph now shows TIFFWriteScanLine is only called by an external node.
   I already compile tiffdither, and I upload it as an attached file. I also write a small python to help analyze the dot file.
   Actually, I do  opt-6.0 -analyze -dot-callgraph tiffdither.bc to generate the dot file. And then modify the dotPath in dotHandle.py. You can modify the python code to help analyze.
   I can't figure out why this happens, and I will be very appreciate if you can help!


Thanks & Regards,
Chaz




 
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