extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
    // Call your code with fuzzer-provided data
    check_buf((char*)data, size);
    return 0;
}

undefined

undefined

apt install afl++ lld-17

docker pull aflplusplus/aflplusplus:stable

git clone --depth 1 --branch stable https://github.com/AFLplusplus/AFLplusplus
cd AFLplusplus
docker build -t aflplusplus .

cat <<'EOF' > ./afl++
#!/bin/sh
AFL_VERSION="${AFL_VERSION:-"stable"}"
case "$1" in
   host)
        shift
        bash -c "$*"
        ;;
    docker)
        shift
        /usr/bin/env docker run -ti \
            --privileged \
            -v ./:/src \
            --rm \
            --name afl_fuzzing \
            "aflplusplus/aflplusplus:$AFL_VERSION" \
            bash -c "cd /src && bash -c \"$*\""
        ;;
    *)
        echo "Usage: $0 {host|docker}"
        exit 1
        ;;
esac
EOF
chmod +x ./afl++

./afl++ <host/docker> afl-system-config

./afl++ host afl-persistent-config
update-grub
reboot
./afl++ <host/docker> afl-system-config

#include <stdint.h>
#include <stddef.h>

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
    // 1. Validate input size if needed
    if (size < MIN_SIZE || size > MAX_SIZE) return 0;

    // 2. Call target function with fuzz data
    target_function(data, size);

    // 3. Return 0 (non-zero reserved for future use)
    return 0;
}

./afl++ <host/docker> afl-clang-fast++ -DNO_MAIN=1 -O2 -fsanitize=fuzzer harness.cc main.cc -o fuzz

./afl++ <host/docker> afl-g++-fast -DNO_MAIN=1 -O2 -fsanitize=fuzzer harness.cc main.cc -o fuzz

./afl++ <host/docker> AFL_USE_ASAN=1 afl-clang-fast++ -DNO_MAIN=1 -O2 -fsanitize=fuzzer harness.cc main.cc -o fuzz

mkdir seeds
echo "aaaa" > seeds/minimal_seed

./afl++ <host/docker> afl-cmin -i out/default/queue -o minimized_corpus -- ./fuzz

./afl++ <host/docker> afl-fuzz -i seeds -o out -- ./fuzz

./afl++ <host/docker> AFL_FAST_CAL=1 afl-fuzz -i seeds -o out -- ./fuzz

out/default/
├── cmdline          # How was the SUT invoked?
├── crashes/         # Inputs that crash the SUT
│   └── id:000000,sig:06,src:000002,time:286,execs:13105,op:havoc,rep:4
├── hangs/           # Inputs that hang the SUT
├── queue/           # Test cases reproducing final fuzzer state
│   ├── id:000000,time:0,execs:0,orig:minimal_seed
│   └── id:000001,src:000000,time:0,execs:8,op:havoc,rep:6,+cov
├── fuzzer_stats     # Campaign statistics
└── plot_data        # Data for plotting

./afl++ <host/docker> afl-whatsup out

apt install gnuplot
./afl++ <host/docker> afl-plot out/default out_graph/

./afl++ <host/docker> ./fuzz out/default/crashes/<test_case>

./afl++ <host/docker> afl-fuzz -M primary -i seeds -o state -- ./fuzz 1>primary.log 2>primary.error &

./afl++ <host/docker> afl-fuzz -S secondary01 -i seeds -o state -- ./fuzz 1>secondary01.log 2>secondary01.error &
./afl++ <host/docker> afl-fuzz -S secondary02 -i seeds -o state -- ./fuzz 1>secondary02.log 2>secondary02.error &

jobs

./afl++ <host/docker> watch -n1 --color afl-whatsup state/

kill $(jobs -p)

./afl++ <host/docker> afl-plot out/default out_graph/

./afl++ <host/docker> AFL_LLVM_CMPLOG=1 make

./afl++ <host/docker> afl-fuzz -c0 -S cmplog -i seeds -o state -- ./fuzz 1>secondary02.log 2>secondary02.error &

./afl++ <host/docker> AFL_USE_ASAN=1 afl-clang-fast++ -DNO_MAIN=1 -O2 -fsanitize=fuzzer harness.cc main.cc -o fuzz

./afl++ <host/docker> AFL_USE_UBSAN=1 afl-clang-fast++ -DNO_MAIN=1 -O2 -fsanitize=fuzzer,undefined harness.cc main.cc -o fuzz

./afl++ <host/docker> afl-clang-fast++ -O2 main_stdin.c -o fuzz_stdin
./afl++ <host/docker> afl-fuzz -i seeds -o out -- ./fuzz_stdin

./afl++ <host/docker> afl-clang-fast++ -O2 main_file.c -o fuzz_file
./afl++ <host/docker> afl-fuzz -i seeds -o out -- ./fuzz_file @@

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef __AFL_COMPILER
#include "argv-fuzz-inl.h"
#endif

void check_buf(char *buf, size_t buf_len) {
    if(buf_len > 0 && buf[0] == 'a') {
        if(buf_len > 1 && buf[1] == 'b') {
            if(buf_len > 2 && buf[2] == 'c') {
                abort();
            }
        }
    }
}

int main(int argc, char *argv[]) {
#ifdef __AFL_COMPILER
    AFL_INIT_ARGV();
#endif

    if (argc < 2) {
        fprintf(stderr, "Usage: %s <input_string>\n", argv[0]);
        return 1;
    }

    char *input_buf = argv[1];
    size_t len = strlen(input_buf);
    check_buf(input_buf, len);
    return 0;
}

curl -O https://raw.githubusercontent.com/AFLplusplus/AFLplusplus/stable/utils/argv_fuzzing/argv-fuzz-inl.h

./afl++ <host/docker> afl-clang-fast++ -O2 main_arg.c -o fuzz_arg
./afl++ <host/docker> afl-fuzz -i seeds -o out -- ./fuzz_arg

undefined

undefined

project(BuggyProgram)
cmake_minimum_required(VERSION 3.0)

add_executable(buggy_program main.cc)

add_executable(fuzz main.cc harness.cc)
target_compile_definitions(fuzz PRIVATE NO_MAIN=1)
target_compile_options(fuzz PRIVATE -O2 -fsanitize=fuzzer-no-link)
target_link_libraries(fuzz -fsanitize=fuzzer)

undefined

undefined