This content originally appeared on DEV Community and was authored by Miguel
As someone passionate about low-level programming, embedded systems, and open-source development, I’ve always wanted to contribute to open source at a larger scale and deepen my understanding of the Linux kernel. That’s why I applied to the Linux Kernel Bug Fixing Fall Program through the LFX Mentorship platform.
I had been following LFX opportunities for a while, and when the Linux kernel bug-fixing mentorship appeared, I knew it was a perfect fit for my interests in systems programming and kernel internals. I applied, highlighting my prior open-source involvement, my low-level programming background, and my motivation to work on real bugs in the kernel. The application required completing preparatory tasks, including building the kernel, learning about fuzzing tools, and submitting an initial patch.
When I was accepted into the program, I felt both excited and challenged — knowing that my work would directly impact one of the most critical pieces of software in the world.
First Weeks – Learning the Landscape
The first weeks were mostly about learning, reading kernel code, and familiarizing myself with the bug-finding and debugging process. I experimented with Syzkaller reports, virtme-ng for quick kernel boots, and a minimal QEMU + BusyBox rootfs to load and test modules.
I quickly realized that every subsystem in the kernel has its own formalities and communication style. My early submissions taught me that clear commit messages, proper subsystem conventions, and concise explanations are critical. After a few “cold showers” (rejections or feedback pointing out style/process issues), I adapted my workflow to be more effective on mailing lists.
Tackling Syzkaller Bugs
My most impactful work during the mentorship was resolving two Syzkaller-reported bugs in the NTFS3 filesystem by backporting fixes to the 6.1-stable tree:
-
fs/ntfs3: Change new sparse cluster processing— Fixed a NULL pointer dereference (syzkaller link). -
fs/ntfs3: Fix shift-out-of-bounds in ntfs_fill_super— Fixed a UBSAN shift-out-of-bounds issue (syzkaller link).
These taught me the full cycle: reproducing a crash from a syzbot repro, analyzing it step-by-step, identifying the relevant upstream fix, validating it in my local environment, and backporting it to the stable tree.
Contributions to Networking Subsystems
Once I gained confidence, I contributed to netdev and xfrm by replacing unsafe strcpy() calls with strscpy() to prevent buffer overflows and improve code robustness:
-
net/tun: Replacedstrcpywithstrscpyforifr_name. -
ipv6/ip6_gre: Replacedstrcpywithstrscpyfor tunnel name. -
xfrm/xfrm_user: Usedstrscpy()foralg_name(merged intoipsec-next).
These contributions required understanding each subsystem’s review process and applying clean-up patches that align with kernel hardening practices.
Tooling and Workflow
During the program, I worked extensively with:
-
Syzkaller /
syz-execprog— For reproducing kernel crashes. - virtme-ng — For fast test cycles with a local kernel build.
- QEMU + BusyBox rootfs — For isolated kernel testing.
- git bisect — For regression hunting.
-
cscope /
ripgrep— For fast code navigation. - Coccinelle — For semantic patching and searching for potential improvements.
- scripts/checkpatch.pl — To ensure coding style compliance.
Lessons Learned from the Community
From my mentors and the wider Linux kernel community, I learned:
- Patience and clarity in technical discussions — Feedback is about improving the patch, not personal criticism.
- Subsystem diversity — Each maintainer has different preferences, from commit message style to patch scope.
- Persistence — Some patches get rejected, and that’s part of the process.
- Efficiency — While waiting for review, keep working on other bugs; don’t stall.
Closing Thoughts
This mentorship significantly improved my ability to read, debug, and modify kernel code. I became more comfortable with tools like Syzkaller, virtme-ng, and Coccinelle, and I learned how to navigate the Linux kernel development process — from reproducing crashes to getting patches merged upstream.
I’m grateful to my mentors and reviewers for their guidance, and I plan to continue contributing to the Linux kernel, focusing on filesystem, networking, and security hardening.
If you’re considering the Linux Kernel Mentorship Program, I highly recommend it — it’s a unique opportunity to grow your technical skills while making meaningful contributions to a critical open-source project.
This content originally appeared on DEV Community and was authored by Miguel
Miguel | Sciencx (2025-08-21T12:00:27+00:00) My Journey in the Linux Kernel Mentorship Program – Bug Fixing and Beyond. Retrieved from https://www.scien.cx/2025/08/21/my-journey-in-the-linux-kernel-mentorship-program-bug-fixing-and-beyond/
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