Porting Syzkaller to ReactOS (Evaluation-1) - GSoC 2020

by Freakston | June 30, 2020

Hey, I am Suraj K Suresh (@Freakston), In this post I’m going to be listing out what I’ve completed in Coding period-1 of GSoC.


The initial part of setting up Syzkaller and being able to fuzz ReactOS is done. The link to grab ReactOS compatible syzkaller is as follows: Github.

The detailed instruction on setting it up can be found here.


  • Boot ReactOS with UBSan enabled.

The branch which has UBSan enabled can be found in extravert34’s fork of ReactOS.

  • Syz-stress and Syz-executor working.

Syz-Stress is the program responsible for generating mutated programs and syz-executor does the execution part. In the upcoming builds I will be working on adding Shared memory support for syz-executor.

  • Initial set of kernel32 function definitions.

Currently the main focus is Ntdll and Kernel32. From the next build onwards I will be adding function descriptions, mostly form Ntdll.

  • Fuzz ReactOS (with around 107 definitions).

The results of the fuzzing were ~4 crashes (2 BSOD’s and 1 freezup). I was not able to capture the reproducer as logging was not enabled.

A few changes were made on the ReactOS part as well, such as exporting a few NT6.0+ functions. The PR can be found here.


  • Setup SSH access on ReactOS.

The SSH access is needed for Syz-manager to communicate with the spawned VM’s.

  • Rebase the head to current master of Google/Syzkaller.

This will enable us to add more features to the syz-executor such as support for KCOV, Shared memory.

  • Syz-manager : Automated VM spawn and fuzz.

A Screenshot of Syz-stress fuzzing ReactOS.