This is a template for a project to help teach how to implement a static dataflow analysis inside LLVM. It involves computing the possible ranges of values for variables and using these ranges to identify potential buffer overflows.

Building with CMake

1. Create a new directory for building.

    mkdir overflowerbuild
   

2. Change into the new directory.

    cd overflowerbuild
   

3. Run CMake with the path to the LLVM source.

    cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=True \
        -DLLVM_DIR=</path/to/LLVM/build>/lib/cmake/llvm/ ../overflower-template
   

4. Run make inside the build directory:

    make
   

This produces a tool called bin/overflower.

Note, building with a tool like ninja can be done by adding -G Ninja to the cmake invocation and running ninja instead of make.

Running

First suppose that you have a program compiled to bitcode:

clang -g -c -emit-llvm ../overflower-template/test/c/01-charbuffer.c -o 01.bc

Running the overflow analyzer:

bin/overflower 01.bc

When you have successfully completed the project, running the overflower as above should print the results in CSV format. The file should be formatted as follows:

<Context>, <Function of access>, <Line of access>, <Size of buffer>, <Possible range for access>