diegolagoglez / dmd-sigsegv-using-di-proof-of-concept

Proof of concept of how D compiler generates a binary that throws a SIGSEGV built against a shared object using interface files (*.di)

Proof of concept of how D compiler (dmd) generates a binary that throws a SIGSEGV when using with *.di files

Introduction

This repository holds a proof of concept of how D compiler (dmd) generates a binary file (test program) that throws a SIGSEGV when it is linked against a library (.so) using an interface file (.di) instead of a source file (*.di) when importing the library API.

Compiling the library is made with or without -H option to generate or not the interface file (.di). After that, the test program is compiled against the library importing the source file (.d).

With this import, as stated in documentation, dmd uses interface files before source files if they are present.

And, when the test program is compiled using that interface file, that program throws a SIGSEGV on every run.

How to compile the library

dmd -fPIC -shared -defaultlib=libphobos2.so -H libtest.d -oflibtest.so

-H is the key of the proof of concept. If it is set, D compiler (dmd) generates libtest.di as an interface file, and when compiling the test program, dmd primary uses this file instead of libtest.d, and this throws a SIGSEGV when the test program calls the function implemented in the library. That SIGSEGV is not thrown when dmd uses the source file (.d) instead of the interface file (.di).

How to compile the test program

dmd main -defaultlib=libphobos2.so -L=-L. -L=-ltest

How to run the test

LD_LIBRARY_PATH=. ./main

Using make

There is a Makefile to automate all previous tasks and works as follows:

make clean  # cleans all compiled/generated files
make run    # compiles the library without -H, the test program an runs it
make run-di # compiles the library with -H, the test programa and runs it

Hardware and software used

• OS : Ubuntu 16.04.3 LTS

• Arch : i386

• dmd : 2.078.1 (installed from DEB package)

• Processor: Intel Pentium M 1.8 GHz

• Memory : 2 GiB

• OS : Ubuntu 16.04.3 LTS

• Arch : x86_64

• dmd : 2.079.0 (from DEB package)

• Processor: Intel Xeon ES-2620 2.00 GHz

• Memory : 32 GiB

Credits

Diego Lago

Repository: GitHub 2018-03-05