The vulnerable area of code can be found in ../cpp/libstrcpy.cpp which has an array of a fixed length that is used in strcpy that copies an unchecked length string into that array.
The app is already compiled with ASAN at the moment so writing an input > than expected size will cause a crash and a logcat dump of the ASAN report.
The UI based fuzzer that uses gdb is located in te fuzz/ui directory. For usage information use python3 uiFuzz.py --help. The tool has not been crafted to activate the emulator on its own so you need to be running the emulator before using it.
The libfuzzer test code is in fuzz/libfuzzer. To compile the test code with libfuzzer and ASAN use
clang -g -O1 -fsanitize=fuzzer,address fuzz/libfuzzer/my_target.cpp -o targetFuzzer.o
OR
clang++ fsanitize=address,fuzzer fuzz/libfuzzer/my_target.cpp -o targetFuzzer.o
After compilation use
./targetFuzzer.oto run the fuzzer directly../targetFuzzer.o -help=1to print the help page for possible options.
(More information can be found in the libfuzzer/llvm site.)
Test code for utilising afl is in fuzz/afl. You need to have cloned afl into your machine and use afl-g++ to compile the source code (it works similar to g++). Post comiplation, you can run the fuzzer with afl-fuzz <compileoutput> -i <corpusdir> -o <outputdir>.
(More information can be found in the google/afl repo.)