This folder contains an example fuzzer for libpng, using LLMP for fast multi-process fuzzing and crash detection. To show off crash detection, we added a ud2 instruction to the harness, edit harness.cc if you want a non-crashing example. It has been tested on Linux.

Build

To build this example, run cargo build --release in this folder. This will call (the build.rs)[./build.rs], which in turn downloads a libpng archive from the web. Then, it will link (the fuzzer)[./src/fuzzer.rs] against (the C++ harness)[./harness.cc] and the instrumented libpng. Afterwards, the fuzzer will be ready to run, from target/frida_libpng.
On unix platforms, you'll need libc++ to build it.

Build For Android

When building for android using a cross-compiler, make sure you have a standalone toolchain, and then add the following:

In the ~/.cargo/config file add a target with the correct cross-compiler toolchain name (in this case aarch64-linux-android, but names may vary) [target.aarch64-linux-android] linker="aarch64-linux-android-clang"
add path to installed toolchain to PATH env variable.
define CLANG_PATH and add target to the build command line: CLANG_PATH=<path to installed toolchain>/bin/aarch64-linux-android-clang cargo -v build --release --target=aarch64-linux-android

Run

This example uses in-process-fuzzing, using the launcher feature, in combination with a Restarting Event Manager. This means running --cores each client will start itself again to listen for crashes and timeouts. By restarting the actual fuzzer, it can recover from these exit conditions.

After building the libpng-harness, too, you can run find . -name libpng-harness.so to find the location of your harness, then run ./target/release/frida_libpng ./libpng-harness.so LLVMFuzzerTestOneInput ./libpng-harness.so --cores=0

Windows

You can also fuzz libpng-1.6.37 on windows with frida mode! (still experimental, we have an issue on frida-gum.)

To build it with visual studio

Install clang for windows (make sure you add LLVM to the system path!) https://github.com/llvm/llvm-project/releases/tag/llvmorg-12.0.1
Run build, this will download and extract libpng-1.6.37 directory.

cargo build --release

Build libpng1.6.37
- Open libpng-1.6.37/projects/vstudio/vstudio.sln
- Open Build->Configuration Manager
  - select Release for Active solution configuration and
  - select ->x64 for Active solution platform (Copy settings from Win32)
- Then for libpng, pngstest, pngtest, pngunknown, pngvalid, zlib in Solution Explorer, choose General -> Configuration Type -> Static library(.lib)
  - C/C++ -> Treat Warnings As Errors -> No
  - C/C++ -> Code Generation -> Runtime Library -> Multi-threaded (/MT)
- Finally, you can build libpng-1.6.37
Compile the harness Fire up a powershell at this directory.

cp .\libpng-1.6.37\projects\vstudio\x64\Release\libpng16.lib .
cp .\libpng-1.6.37\projects\vstudio\x64\Release\zlib.lib .
cp .\target\release\frida_libpng.exe .
clang++ -O3 -c -I.\libpng-1.6.37 .\harness.cc -o .\harness.o
clang++ -L.\zlib.dll .\harness.o .\libpng16.lib -lzlib -shared -o .\libpng-harness.dll

Run the fuzzer

./frida_libpng.exe ./libpng-harness.dll LLVMFuzzerTestOneInput ./libpng-harness.dll --cores=0