Re: [PATCH v4 0/6] KFuzzTest: a new kernel fuzzing framework

[Alexander Potapenko <glider@google.com>]

On Mon, Jan 12, 2026 at 8:28 PM Ethan Graham <ethan.w.s.graham@gmail.com> wrote:
>
> This patch series introduces KFuzzTest, a lightweight framework for
> creating in-kernel fuzz targets for internal kernel functions.
>
> The primary motivation for KFuzzTest is to simplify the fuzzing of
> low-level, relatively stateless functions (e.g., data parsers, format
> converters) that are difficult to exercise effectively from the syscall
> boundary. It is intended for in-situ fuzzing of kernel code without
> requiring that it be built as a separate userspace library or that its
> dependencies be stubbed out.
>
> Following feedback from the Linux Plumbers Conference and mailing list
> discussions, this version of the framework has been significantly
> simplified. It now focuses exclusively on handling raw binary inputs,
> removing the complexity of the custom serialization format and DWARF
> parsing found in previous iterations.

Thanks, Ethan!
I left some comments, but overall I think we are almost there :)

A remaining open question is how to handle concurrent attempts to
write data to debugfs.
Some kernel functions may not support reentrancy, so we'll need to
either document this limitation or implement proper per-test case
locking.