Improve UML page fault handler by ptesarik

Description

Improve UML handling of segmentation faults in kernel mode. Although such page faults are generally caused by a kernel bug, it is annoying if they cause an infinite loop, or panic the kernel. More importantly, a robust implementation allows to write KUnit tests for various guard pages, preventing potential kernel self-protection regressions.

Goals

Convert the UML page fault handler to use oops_* helpers, go through a few review rounds and finally get my patch series merged in 6.14.

Resources

Wrong initial attempt: https://lore.kernel.org/lkml/20231215121431.680-1-petrtesarik@huaweicloud.com/T/

early stage kdump support by mbrugger

Project Description

When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

Goal for the Hackweeks

1. Investigate if this is possible and the implications it would have (done in HW21)
2. Hack up a PoC (done in HW22 and HW23)
3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

update HW23

• I was able to include the crash kernel into the kernel Image.
• I'll need to find a way to load that from init/main.c:start_kernel() probably after kcsan_init()
• I workaround for a smoke test was to hack kexec_file_load() systemcall which has two problems:
  1. My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
  2. As the crash kernel is part of init.data it will be already stale once I can call kexec_file_load() from user-space.

The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.

update HW24

• Day1
  • rebased on v6.12 with no problems others then me breaking the config
  • setting up a new compilation and qemu/virtme env
  • getting desperate as nothing works that used to work
• Day 2
  • getting to call the invocation of loading the early kernel from __init after kcsan_init()

• Day 3

  • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
  • code refactoring
  • I'm now able to load the crash kernel
  • When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in elfcorehdr_read_notes()

• Day 4

  • crash systems crashes (no pun intended) in copy_old_mempage() link; will need to understand elfcorehdr...
  • call path vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()

• Day 5

  • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
  • fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/

• TODOs

  • fix elfcorehdr so that we actually can make use of all this...
  • test where in the boot __init() chain we can/should call kexec_early_dump()

Contributing to Linux Kernel security by pperego

Description

A couple of weeks ago, I found this blog post by Gustavo Silva, a Linux Kernel contributor.

I always strived to start again into hacking the Linux Kernel, so I asked Coverity scan dashboard access and I want to contribute to Linux Kernel by fixing some minor issues.

I want also to create a Linux Kernel fuzzing lab using qemu and syzkaller

Goals

1. Fix at least 2 security bugs
2. Create the fuzzing lab and having it running

The story so far

• Day 1: setting up a virtual machine for kernel development using Tumbleweed. Reading a lot of documentation, taking confidence with Coverity dashboard and with procedures to submit a kernel patch
• Day 2: I read really a lot of documentation and I triaged some findings on Coverity SAST dashboard. I have to confirm that SAST tool are great false positives generator, even for low hanging fruits.
• Day 3: Working on trivial changes after I read this blog post: https://www.toblux.com/posts/2024/02/linux-kernel-patches.html. I have to take confidence with the patch preparation and submit process yet.
  • First trivial patch sent: using strtruefalse() macro instead of hard-coded strings in a staging driver for a lcd display
  • Fix for a dereference before null check issue discovered by Coverity (CID 1601566) https://scan7.scan.coverity.com/#/project-view/52110/11354?selectedIssue=1601566
• Day 4: Triaging more issues found by Coverity.
  • The patch for CID 1601566 was refused. The check against the NULL pointer was pointless so I prepared a version 2 of the patch removing the check.
  • Fixed another dereference before NULL check in iwlmvmparsewowlaninfo_notif() routine (CID 1601547). This one was already submitted by another kernel hacker :(
• Day 5: Wrapping up. I had to do some minor rework on patch for CID 1601566. I found a stalker bothering me in private emails and people I interacted with me, advised he is a well known bothering person. Markus Elfring for the record.

• Wrapping up: being back doing kernel hacking is amazing and I don't want to stop it. My battery pack is completely drained but changing the scope gave me a great twist and I really want to feel this energy not doing a single task for months.

  I failed in setting up a fuzzing lab but I was too optimistic for the patch submission process.

The patches

1

FizzBuzz OS by mssola

Project Description

FizzBuzz OS (or just fbos) is an idea I've had in order to better grasp the fundamentals of the low level of a RISC-V machine. In practice, I'd like to build a small Operating System kernel that is able to launch three processes: one that simply prints "Fizz", another that prints "Buzz", and the third which prints "FizzBuzz". These processes are unaware of each other and it's up to the kernel to schedule them by using the timer interrupts as given on openSBI (fizz on % 3 seconds, buzz on % 5 seconds, and fizzbuzz on % 15 seconds).

This kernel provides just one system call, write, which allows any program to pass the string to be written into stdout.

This project is free software and you can find it here.

Goal for this Hackweek

• Better understand the RISC-V SBI interface.
• Better understand RISC-V in privileged mode.
• Have fun.

Resources

• SBI v2.0 ratified specification
• Blog post on SBI
• mssola/fbos

Results

The project was a resounding success Lots of learning, and the initial target was met.

Hacking on sched_ext by flonnegren

Description

Sched_ext upstream has some interesting issues open for grabs:

• core event counters
• topology: Use cpumasks

Goals

Send patches to sched_ext upstream

Also set up perfetto to trace some of the example schedulers.

Resources

https://github.com/sched-ext/scx

Automated Test Report reviewer by oscar-barrios

Description

In SUMA/Uyuni team we spend a lot of time reviewing test reports, analyzing each of the test cases failing, checking if the test is a flaky test, checking logs, etc.

Goals

Speed up the review by automating some parts through AI, in a way that we can consume some summary of that report that could be meaningful for the reviewer.

Resources

No idea about the resources yet, but we will make use of:

• HTML/JSON Report (text + screenshots)
• The Test Suite Status GithHub board (via API)
• The environment tested (via SSH)
• The test framework code (via files)

Testing and adding GNU/Linux distributions on Uyuni by juliogonzalezgil

Join the Gitter channel! https://gitter.im/uyuni-project/hackweek

Uyuni is a configuration and infrastructure management tool that saves you time and headaches when you have to manage and update tens, hundreds or even thousands of machines. It also manages configuration, can run audits, build image containers, monitor and much more!

Currently there are a few distributions that are completely untested on Uyuni or SUSE Manager (AFAIK) or just not tested since a long time, and could be interesting knowing how hard would be working with them and, if possible, fix whatever is broken.

For newcomers, the easiest distributions are those based on DEB or RPM packages. Distributions with other package formats are doable, but will require adapting the Python and Java code to be able to sync and analyze such packages (and if salt does not support those packages, it will need changes as well). So if you want a distribution with other packages, make sure you are comfortable handling such changes.

No developer experience? No worries! We had non-developers contributors in the past, and we are ready to help as long as you are willing to learn. If you don't want to code at all, you can also help us preparing the documentation after someone else has the initial code ready, or you could also help with testing :-)

The idea is testing Salt and Salt-ssh clients, but NOT traditional clients, which are deprecated.

To consider that a distribution has basic support, we should cover at least (points 3-6 are to be tested for both salt minions and salt ssh minions):

1. Reposync (this will require using spacewalk-common-channels and adding channels to the .ini file)
2. Onboarding (salt minion from UI, salt minion from bootstrap scritp, and salt-ssh minion) (this will probably require adding OS to the bootstrap repository creator)
3. Package management (install, remove, update...)
4. Patching
5. Applying any basic salt state (including a formula)
6. Salt remote commands
7. Bonus point: Java part for product identification, and monitoring enablement
8. Bonus point: sumaform enablement (https://github.com/uyuni-project/sumaform)
9. Bonus point: Documentation (https://github.com/uyuni-project/uyuni-docs)
10. Bonus point: testsuite enablement (https://github.com/uyuni-project/uyuni/tree/master/testsuite)

If something is breaking: we can try to fix it, but the main idea is research how supported it is right now. Beyond that it's up to each project member how much to hack :-)

• If you don't have knowledge about some of the steps: ask the team
• If you still don't know what to do: switch to another distribution and keep testing.

This card is for EVERYONE, not just developers. Seriously! We had people from other teams helping that were not developers, and added support for Debian and new SUSE Linux Enterprise and openSUSE Leap versions :-)

Pending

FUSS

FUSS is a complete GNU/Linux solution (server, client and desktop/standalone) based on Debian for managing an educational network.

https://fuss.bz.it/

Seems to be a Debian 12 derivative, so adding it could be quite easy.

• [W] Reposync (this will require using spacewalk-common-channels and adding channels to the .ini file)
• [W] Onboarding (salt minion from UI, salt minion from bootstrap script, and salt-ssh minion) (this will probably require adding OS to the bootstrap repository creator) --> Working for all 3 options (salt minion UI, salt minion bootstrap script and salt-ssh minion from the UI).
• [W] Package management (install, remove, update...) --> Installing a new package works, needs to test the rest.
• [I] Patching (if patch information is available, could require writing some code to parse it, but IIRC we have support for Ubuntu already). No patches detected. Do we support patches for Debian at all?
• [W] Applying any basic salt state (including a formula)
• [W] Salt remote commands
• [ ] Bonus point: Java part for product identification, and monitoring enablement

Yearly Quality Engineering Ask me Anything - AMA for not-engineering by szarate

Goal

Get a closer look at how developers work on the Engineering team (R & D) of SUSE, and close the collaboration gap between GSI and Engineering

Why?

Santiago can go over different development workflows, and can do a deepdive into how Quality Engineering works (think of my QE Team, the advocates for your customers), The idea of this session is to help open the doors to opportunities for collaboration, and broaden our understanding of SUSE as a whole.

Objectives

• Give $audience a small window on how to get some questions answered either on the spot or within days of how some things at engineering are done
• Give Santiago Zarate from Quality Engineering a look into how $audience sees the engineering departments, and find out possibilities of further collaboration

How?

By running an "Ask me Anything" session, which is a format of a kind of open Q & A session, where participants ask the host multiple questions.

How to make it happen?

I'm happy to help joining a call or we can do it async (online/in person is more fun). Ping me over email-slack and lets make the magic happen!. Doesn't need to be during hackweek, but we gotta kickstart the idea during hackweek ;)

Rules

The rules are simple, the more questions the more fun it will be; while this will be only a window into engineering, it can also be the place to help all of us get to a similar level of understanding of the processes that are behind our respective areas of the organization.

Dynamics

The host will be monitoring the questions on some pre-agreed page, and try to answer to the best of their knowledge, if a question is too difficult or the host doesn't have the answer, he will do his best to provide an answer at a later date.

Atendees are encouraged to add questions beforehand; in the case there aren't any, we would be looking at how Quality Engineering tests new products or performs regression tests

Agenda

• Introduction of Santiago Zarate, Product Owner of Quality Engineering Core team
• Introduction of the Group/Team/Persons interested
• Ice breaker
• AMA time! Add your questions $PAGE
• Looking at QE Workflows: How is
  • A maintenance update being tested before being released to our customers
  • Products in development are tested before making it generally available
• Engineering Opportunity Board

Drag Race - comparative performance testing for pull requests by balanza

Description

«Sophia, a backend developer, submitted a pull request with optimizations for a critical database query. Once she pushed her code, an automated load test ran, comparing her query against the main branch. Moments later, she saw a new comment automatically added to her PR: the comparison results showed reduced execution time and improved efficiency. Smiling, Sophia messaged her team, “Performance gains confirmed!”»

Goals

• To have a convenient and ergonomic framework to describe test scenarios, including environment and seed;
• to compare results from different tests
• to have a GitHub action that executes such tests on a CI environment

Resources

The MVP will be built on top of Preevy and K6.

Make more sense of openQA test results using AI by livdywan

Description

AI has the potential to help with something many of us spend a lot of time doing which is making sense of openQA logs when a job fails.

User Story

Allison Average has a puzzled look on their face while staring at log files that seem to make little sense. Is this a known issue, something completely new or maybe related to infrastructure changes?

Goals

• Leverage a chat interface to help Allison
• Create a model from scratch based on data from openQA
• Proof of concept for automated analysis of openQA test results

Bonus

• Use AI to suggest solutions to merge conflicts
  • This would need a merge conflict editor that can suggest solving the conflict
• Use image recognition for needles

Resources

• TensorFlow
• open-webui
• openQA instance of openSUSE
• openQA documentation

Timeline

Day 1

• Conversing with open-webui to teach me how to create a model based on openQA test results
  • Asking for example code using TensorFlow in Python
  • Discussing log files to explore what to analyze
  • Drafting a new project called Testimony (based on Implementing a containerized Python action) - the project name was also suggested by the assistant

Day 2

• Using NotebookLLM (Gemini) to produce conversational versions of blog posts
  • Writing openQA tests in Python
  • Developing in distrobox containers
• Researching the possibility of creating a project logo with AI
  • Asking open-webui, persons with prior experience and conducting a web search for advice

Highlights

• I briefly tested compared models to see if they would make me more productive. Between llama, gemma and mistral there was no amazing difference in the results for my case.
• Convincing the chat interface to produce code specific to my use case required very explicit instructions.
• Asking for advice on how to use open-webui itself better was frustratingly unfruitful both in trivial and more advanced regards.
• Documentation on source materials used by LLM's and tools for this purpose seems virtually non-existent - specifically if a logo can be generated based on particular licenses

Outcomes

• Chat interface-supported development is providing good starting points and open-webui being open source is more flexible than Gemini. Although currently some fancy features such as grounding and generated podcasts are missing.
• Allison still has to be very experienced with openQA to use a chat interface for test review. Publicly available system prompts would make that easier, though.