1.4 KiB
Compiling simple_target.c
You shouldn't need to compile simple_target.c since a MIPS binary version is pre-built and shipped with afl-unicorn. This file documents how the binary was built in case you want to rebuild it or recompile it for any reason.
The pre-built binary (simple_target.bin) was built by cross-compiling simple_target.c for MIPS using the mips-linux-gnu-gcc package on an Ubuntu 16.04 LTS system. This cross compiler (and associated binutils) was installed from apt-get packages:
sudo apt-get install gcc-mips-linux-gnu
simple_target.c was compiled without optimization, position-independent, and without standard libraries using the following command line:
mips-linux-gnu-gcc -o simple_target.elf simple_target.c -fPIC -O0 -nostdlib
The .text section from the resulting ELF binary was then extracted to create the raw binary blob that is loaded and emulated by simple_test_harness.py:
mips-linux-gnu-objcopy -O binary --only-section=.text simple_target.elf simple_target.bin
In summary, to recreate simple_taget.bin execute the following:
mips-linux-gnu-gcc -o simple_target.elf simple_target.c -fPIC -O0 -nostdlib
&& mips-linux-gnu-objcopy -O binary --only-section=.text simple_target.elf simple_target.bin
&& rm simple_target.elf
Note that the output of this is padded with nulls for 16-byte alignment. This is important when emulating it, as NOPs will be added after the return of main() as necessary.