Hello Everyone,
It's been two months since I have started working on Kernel Address
Sanitizer as a part of GSoC'18 and I would like to update everyone on what
all I have managed to complete during the second coding period.
I finished successfully building and booting a basic kernel with KASan
function stubs by the end of the first coding period
<http://blog.netbsd.org/tnf/entry/gsoc_2018_reports_kernel_address>. I
started by copying the entire code for KASan from Linux and making it build
in NetBSD. The features that I have managed to port are
- The __asan functions which are inserted in the code by the compiler
- The basic checking and poisoning framework
- Poisoning of a lwp's stack.
- Basic report infrastructure - (Allocator cache based functions have
not been done)
I have also managed to learn more about memory management in the Linux
kernel to understand the KASan code (Referring to Linux code and
Professional Linux kernel architecture book).
I am currently working on getting the shadow memory region allocated during
boot time. We are proceeding in a different route by using high-level
allocator functions instead of changing the page tables directly(The Linux
way!! ). We believe that this would help in making the code more machine
independent and also reduce the code size.
There is a lot of work that remains to be done. This will require me to go
much deeper into the Linux and the NetBSD kernel, and I will also try to
help in improving documentation as I do the same. Features that we plan to
work on immediately are :
- Fixing Licensing issues
- Allocator hooks and functions
- Quarantine list for page allocation
- Boot to a shell with KASan
- Write ATF tests for KASan
A more in detail article has been posted on the blog
<http://blog.netbsd.org/tnf/entry/gsoc_2018_report_kernel_address>.
Most of this would not have been possible without the suggestions and
guidance provided by Kamil. Many thanks to the NetBSD community who have
been supportive throughout.
--
Regards,
Siddharth
