为什么afl++不能编译ImageMagick？

Question

我正在尝试用工具afl (链接)进行一些模糊测试。我下载了ImageMagick 如文档中所述的源代码，但是当我尝试使用afl编译器运行./configure时，会得到一个错误：

$ CC=/usr/local/bin/afl-gcc CXX=/usr/local/bin/afl-g++ ./configure --disable-shared
[...]
checking whether we are using the GNU C++ compiler... no
checking whether /usr/local/bin/afl-g++ accepts -g... no
checking dependency style of /usr/local/bin/afl-g++... none
checking how to run the C++ preprocessor... /lib/cpp
configure: error: in `/home/ubuntu/ImageMagick-7.0.10':
configure: error: C++ preprocessor "/lib/cpp" fails sanity check
See `config.log' for more details

如果我尝试使用默认的c++编译器，一切看起来都很好：

$ CC=/usr/local/bin/afl-gcc ./configure --disable-shared #this works

如何使编译器运行？

更新

从config.log内部看，问题似乎与ImageMagick无法检查afl-g++版本有关：

configure:15015: checking for C++ compiler version
configure:15024: /usr/local/bin/afl-g++ --version >&5
)B[?25h[0m[1;91m
[-] PROGRAM ABORT : [1;97mOops, failed to execute 'g++' - check your PATH[1;91m
         Location : [0mmain(), afl-gcc.c:334

configure:15035: $? = 1

不管怎么说，afl-g++似乎很管用：

$ afl-g++
afl-cc 2.52b by <lcamtuf@google.com>

This is a helper application for afl-fuzz. It serves as a drop-in replacement
for gcc or clang, letting you recompile third-party code with the required
runtime instrumentation. A common use pattern would be one of the following:

  CC=/usr/local/bin/afl-gcc ./configure
  CXX=/usr/local/bin/afl-g++ ./configure

You can specify custom next-stage toolchain via AFL_CC, AFL_CXX, and AFL_AS.
Setting AFL_HARDEN enables hardening optimizations in the compiled code.

但是afl-g++ -v报告错误：

$ afl-g++ -v
afl-cc 2.52b by <lcamtuf@google.com>

[-] PROGRAM ABORT : Oops, failed to execute 'g++' - check your PATH
         Location : main(), afl-gcc.c:334

Answer 1

结果发现，问题在于我的系统中没有g++。可能是因为我已经安装了Ubuntu20.04LTS的最小版本。我安装了g++

sudo apt install g++

现在一切似乎都正常了。

Answer 2

你被限制使用afl的gcc吗？如果没有，请使用它们的clang包装：

我可以像这样启动AFL：

git clone https://github.com/ImageMagick/ImageMagick.git ImageMagick-7.0.10
cd ImageMagick-7.0.10

CC=afl-clang CXX=afl-clang++ ./configure --disable-shared
make

#prepare AFL environment
AFL_SKIP_CPU_FREQ=1 AFL_I_DONT_CARE_ABOUT_MISSING_CRASHES=1 afl-fuzz -i ./in -o ./out -- ./utilities/magick @@ /dev/null

显然，像这样启动AFL很难有意义--我只是说我能够以这种方式快速启动它。