AFLplusplus/instrumentation/README.cmplog.md
2021-03-09 22:09:58 +01:00

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# CmpLog instrumentation
The CmpLog instrumentation enables logging of comparison operands in a
shared memory.
These values can be used by various mutators built on top of it.
At the moment we support the RedQueen mutator (input-2-state instructions only),
for details see [the RedQueen paper](https://www.syssec.ruhr-uni-bochum.de/media/emma/veroeffentlichungen/2018/12/17/NDSS19-Redqueen.pdf).
## Build
To use CmpLog, you have to build two versions of the instrumented target
program.
The first version is built using the regular AFL++ instrumentation.
The second one, the CmpLog binary, is built with setting AFL_LLVM_CMPLOG during the compilation.
For example:
```
./configure --cc=~/path/to/afl-clang-fast
make
cp ./program ./program.afl
make clean
export AFL_LLVM_CMPLOG=1
./configure --cc=~/path/to/afl-clang-fast
make
cp ./program ./program.cmplog
unset AFL_LLVM_CMPLOG
```
## Use
AFL++ has the new `-c` option that needs to be used to specify the CmpLog binary (the second
build).
For example:
```
afl-fuzz -i input -o output -c ./program.cmplog -m none -- ./program.afl @@
```
Be sure to use `-m none` because CmpLog can map a lot of pages.