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.

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 careful with the usage of -m because CmpLog can map a lot of pages.