#kernel
Linux debugging, profiling and tracing training
Very cool course by @bootlin
Slides: https://bootlin.com/doc/training/debugging/debugging-slides.pdf
Lab exercises: https://bootlin.com/doc/training/debugging/debugging-labs.pdf
Lab material (.tar.xz): https://bootlin.com/doc/training/debugging/debugging-labs.tar.xz
#Linux #kernel 6.4-rc4 is out – about half a day earlier than usual:
https://lore.kernel.org/lkml/CAHk-=whwNMtwpMxcsdC4bysY+5E9E_wNeUz=R-iciy3DJwQ+vg@mail.gmail.com/ #LinuxKernel
```I'm traveling most of the day today, so the 6.4-rc4 release is tagged and pushed out a few hours earlier than usual.
[…]
Nothing stands out to me, but the shortlog is appended for people who want to scroll through the details.
Please do continue testing,
Linus```
The fix for the #Linux #kernel #XFS metadata corruption issue in 6.3.y that made the news has been found and is now queued for #LinuxKernel 6.3.5:
https://lore.kernel.org/all/ZHKB%2FKD1yyx77fop@dread.disaster.area/
```A regression in 6.3.0 has been identified in XFS that causes filesystem corruption. It has been seen in the wild by a number of users […]
A reproducer for the corruption was found yesterday and, soon after than, the cause of the corruption reports was identified. […]```
"Fun" regression:
#Linux #kernel >= v6.2 apparently no longer boot on Apple's Virtualization.framework (x86_64) due to a change of the LINUX_EFISTUB_MINOR_VERSION.
```Surprisingly, v2.0 and v3.0 boot, although v1.1, v2.1, v2.2, v3.1, etc. do not boot.
Looks like Apple's vmlinuz loader only requires LINUX_EFISTUB_MINOR_VERSION to be 0x0 and does not care about LINUX_EFISTUB_MAJOR_VERSION.```
#sigh 😩
https://lore.kernel.org/lkml/CAG8fp8Teu4G9JuenQrqGndFt2Gy+V4YgJ=hN1xX7AD940YKf3A@mail.gmail.com/
FWIW, this is the proposed fix: https://lore.kernel.org/linux-efi/CAG8fp8Te=oT1JJhTpOZvgWJrgcTq2DXan8UOVZ=KYCYNa8cKog@mail.gmail.com/
What do i do if my laptop says please unlock disk sda6_crypt #kernel
Some updates ...for the curious ... :)
#linux #linuxkernel #kernel #opensource #linuxadmin #sysadmin #operatingsystem #git
Cum să verificați versiunea de nucleu în Linux
https://www.hardxroot.guru/cum-sa-verificati-versiunea-de-nucleu-in-linux/
# hardxrootro #hardxroot #kernel #linux #terminal
Cum să verificați versiunea de nucleu în Linux
https://www.hardxroot.guru/cum-sa-verificati-versiunea-de-nucleu-in-linux/
Can not mount a partition having XFS filesystem and block size of 64K #partitioning #kernel #mount
#Linux #Kernel module running #WASM filters with wasm3 - https://github.com/cisco-open/wasm-kernel-module #dailylinks
"#drgn is a powerful and flexible [#Linux #kernel] debugger. With drgn, one can write scripts in python to analyze either a live system or a vmcore or a program. […] With drgn, the vmcore analysis seems like natural coding. Having the extensive collection of python libraries also helps, as we can use complex algorithms and data structures to aid with system analysis."
https://blogs.oracle.com/linux/post/enter-the-drgn #LinuxKernel
Intro: Kicksecure Hardened Debian Linux Distribution With Kernel Changes / Upgrades Over Tor & Live Boot (Run On RAM / Forget) Options
(Whonix is based on Kicksecure)
#Linux #FOSS #Kicksecure #whonix #Debian #kernel #Tor #operatingsystems #infosec #Cybersecurity #privacy
The latest iteration of Bodhi Linux is available for testing https://www.linux-magazine.com/Online/News/Bodhi-Linux-7.0-Beta-Ready-for-Testing #BodhiLinux #Moksha #Ubuntu #kernel #modules #software #updates #beta
Having trouble moving symlinks from backup to boot partition #boot #dualboot #kernel #symboliclink #cp
We're getting closer and closer to the microconference submission deadline on June 1 for #LinuxPlumbers and we're running out of slots. So better hurry up and submit now!
https://lpc.events/event/17/page/200-proposed-microconferences
Interesting, the #Linux #kernel device mapper target "dm-vdo" that allows deduplication and compression is finally submitted upstream:
v1: https://lore.kernel.org/all/20230509010545.72448-1-corwin@redhat.com/
v2: https://lore.kernel.org/all/20230523214539.226387-1-corwin@redhat.com/
122 files changed, 58741 insertions(+) 🥴
```[…] The dm-vdo target provides inline deduplication, compression, zero-block elimination, and thin provisioning. A dm-vdo target can be backed by up to 256TB of storage, and can present a logical size of up to 4PB. […]``` #LinuxKernel #DeviceMapper
...and some peeking ...
#linux #linuxkernel #kernel #opensource #operatingsystemadministration
Issue downgrading kernel to 5.19.0-35 from 5.19.0-42 for Intel Arc GPU driver #drivers #packagemanagement #kernel #intelgraphics
Friendly reminder on the existence of this interactive map of the Linux kernel.
High level overview of how the Line kernel is structured.
Map: https://makelinux.github.io/kernel/map/
Source repo: https://github.com/makelinux/linux_kernel_map
Voici un outil qui permet de tester la configuration du noyau Linux et de voir si vous êtes concernés par la CVE-2023-32233 (et d'autres ...) qui affecte Netfilter. Si CONFIG_USER_NS_UNPRIVILEGED est défini sur Y, vous êtes vulnérable. Apparemment cet option a été activée aussi sur le kernel hardened. Sur Debian vous pouvez modifier l'option du noyau en définissant sysctl kernel.unprivileged_userns_clone=1 sur 0
https://hacker-gadgets.com/blog/2021/06/18/kconfig-hardened-check-a-tool-for-checking-the-hardening-options-in-the-linux-kernel-config/
#linux #kernel #cve #vulnérabilité
#OffensiveCon23 – #Exploit Engineering – Attacking the #Linux #Kernel
// by @saidelike & @alexjplaskett
Remove the most current kernel #boot #kernel #virtualization
Bluetooth Issues on Ubuntu 22.04.2 LTS Kernel 5.19.0-42-generic #kernel #bluetooth #intel
Syntax error in /etc/default/console-setup when running "sudo update-initramfs -u -k 5.19.0-31-generic" #kernel #dpkg #initramfs
Example of buffer overflow in Linux kernel (6.2.0-rc1) with exploit PoC by Davide Ornaghi
(CVE-2023-0179 affecting nftables)
```You don't want the #kernel to have a stable [driver] API: it'll kill #Linux.```
@gregkh said that a few days ago here: https://www.youtube.com/watch?v=yilvkzDrRLk&t=2464s
It's good that he's not getting tired of repeating this, as it's a slightly hidden aspect – and thus something many people easily miss. #LinuxKernel
#Linux #kernel 6.4-rc3 is out:
https://lore.kernel.org/lkml/CAHk-=wgL4Sa64qUZkpAs06t9UKoNyAYqBpzmukefJz8P8sa2=Q@mail.gmail.com/
```Here we are, another week gone by, and another rc released.
Nothing really huge stands out there. […]
Please do continue testing,
Linus```
Analysis and exploitation of a Linux kernel heap buffer overflow in iSCSI data structures (CVE-2021-27365)
https://blog.grimm-co.com/2021/03/new-old-bugs-in-linux-kernel.html#Linux
Fun corner cases:
If you encounter a #LinuxKernel regression when updating from #Linux v6.2.14 to v6.3.2, it's unclear if it's a mainline regression (e.g. v6.2..v6.3) or a stable-specific regression – and thus unclear who has to handle it[1].
That's because the stable team might have caused the issue with a broken backport that went into #kernel v6.3.2 – which might have hit v6.2.15 also, which was released in parallel and has many changes in common with 6.3.2.
[1] see https://docs.google.com/document/d/1Yu1QdK9PicMrkPWTHEMWlJ7AC70gXZPtpTA_oCEbKkE/edit?usp=sharing
```I have two options: to pull or not to pull.```
Linus explains why he sometimes refuses to pull from #Linux #kernel subsystem trees when he is unhappy with their maintenance.
```I think the solution may be for those affected people to help Mauro & co.
Clearly the media maintenance doesn't have enough time. I'm not going to pull from a tree where I know that it then may take six *weeks* and one whole release for simple bugs to be fixed.```
https://lore.kernel.org/lkml/CAHk-%3Dwjypw2PL-w5ZBxY97SgRWd21f2V2Cuyw-ebsiTpSNQjBg@mail.gmail.com/ #LinuxKernel
Wanna know what the #Linux #kernel 6.4 brings, which is expected on June 25 or July 2?
Then check out the two @LWN articles about the big changes merged for this version now freely available:
Greg released a bunch of new stable and longterm #kernel today with the usual "must upgrade" notice.
Among them is #Linux 6.2.16, which marks the end of the 6.2.y series; users are advised switching to #LinuxKernel 6.3.y.
"Why your #Linux #kernel bug report might be ignored or is fruitless":
https://docs.google.com/document/d/1Yu1QdK9PicMrkPWTHEMWlJ7AC70gXZPtpTA_oCEbKkE/edit?usp=sharing
Feel free to leave comments.
I wonder what to do with that text[1]. Add it to the #LinuxKernel's documentation? Just publish it somewhere and keep it updated?
[1] I had a few incidents recently that made me think "such a text would be really good to have" -- and then simply started to work on in on two longer train rides.
Original blog post by Max Kellermann on Dirty pipe (CVE-2022-0847)
Posted v1 of a patch reworking the section about "Expectations and best practices for fixing regressions" in the #Linux #kernel's "Handling #regressions" document:
https://lore.kernel.org/linux-doc/6971680941a5b7b9cb0c2839c75b5cc4ddb2d162.1684139586.git.linux@leemhuis.info/ #LinuxKernel
Sadly the section grew somewhat, but it now covers the interaction with stable/longterm kernels better and groups the rules of thumb to make the text easier to read.
#Linux #kernel 6.4-rc2 is out:
```[…] This being rc2, it's been a fairly calm week as people are only starting to find any issues from the merge window, but it all looks fine. […]```
https://lore.kernel.org/lkml/CAHk-=wj3jDtVCi2LqyijGzut2cq=AkPrAMfF0+6gtZ1WB6ruWQ@mail.gmail.com/ #LinuxKernel
Aktueller Stand:
- alter #Kernel kann nicht #drucken
- neuere Kernel kann ich noch nicht #booten, vermutlich ist die linuxrc für #LUKS und #ZFS inkompatibel
- in den alten Kernel das Drucken einkompilieren: dafür ist der #Compiler zu neu
- mit der Kamera kann ich aber mittlerweile reden, da brauchte das Makefile nur ein -ltinfo nach einem #ncurses-Update
- die Grafik flackert, ist mir jetzt aber egal
… noch knapp drei Stunden, bis wir losmüssen, also #easypeasy alles …
Nice blog post by Chris Bao on Linu kernel NetFilter sub-system
https://levelup.gitconnected.com/write-a-linux-firewall-from-scratch-based-on-netfilter-462013202686
```[…] clone the memory of VMs in a Copy-on-Write fashion [using the #Linux #kernel's #userfaultfd infra] without having to go through the filesystem […] opens up the opportunity to load memory from new sources, like (compressed) files, or even the network […]
We can now reliably fork a VM within 1.5s, regardless of how much memory is used for the VM […]```
https://codesandbox.io/blog/cloning-microvms-using-userfaultfd
Linux 6.5 - improved handling for Intel's hybrid CPUs /w hyper threading :atom:
The patches were queued today into TIP's sched/core Git branch - v6.5 kernel cycle should kick off in early July.
What more notable? Better handling on Meteor Lake. Meteor Lake needed special handling with its CPUs of different maximum frequency.
=> https://www.phoronix.com/news/Linux-6.4-Avoid-Unnecessary-SMT
#Linux #kernel #Intel #hybrid #CPU #Git #TIP #July #Meteor #Lake #patches #Phoronix #hardware #technical
#LKML quote of the day from @torvalds on avoiding compiler warnings:
```you can make some compilers happy all of the time, and all compilers happy some of the time, but you can't make all compilers happy all of the time```
https://lore.kernel.org/all/CAHk-=whtWTqXXD29n4z0qni-xM_4OPE-6u3vw_qjkiz05BHVZg@mail.gmail.com/ #LinuxKernel #Linux #kernel
Kent submitted the #bcachefs filesystem ("a new COW fs") for review and #Linux #kernel inclusion: https://lore.kernel.org/all/20230509165657.1735798-1-kent.overstreet@linux.dev/
```Status:
Snapshots have been declared stable; […]
Erasure coding is getting really close; […]
Tons of scalabality work finished over the past year […]
```
Reminder, wenn ihr Meldungen wie "Root-Rechte für lokale Angreifer dank Lücken im #Linux-#Kernel"[1] lest, denkt immer dran:
Das ist nur die Spitze des Eisbergs.
Letztes Jahr etwa gab es über 300 Schwachstellen beim #LinuxKernel, die CVE-IDs bekommen haben[2]; und sicher Dutzende oder vermutlich eher Hunderte, die keinen bekommen haben, weil die Entwickler vieles stillschweigend beseitigen[3].
[1] https://www.heise.de/news/Luecken-im-Linux-Kernel-erlauben-lokale-Rechteausweitung-8992648.html
[2] https://www.cvedetails.com/product/47/Linux-Linux-Kernel.html
[3] https://www.heise.de/select/ct/2021/16/2117313221941668529 #paywall
Great website if you need a quick reference to Linux kernel syscalls (numbers)
[CVE-2023-32233] #Linux #kernel use-after-free in #Netfilter nf_tables when processing batch requests can be abused to perform arbitrary reads and writes in kernel memory
Interesting things the #Linux #kernel's #XFS developers are doing:
```Oh, CONFIG_XFS_DEBUG=y, which means: […] We randomly chose a near block allocation strategy to use to improve code coverage, not the optimal one for IO performance. Hence the CPU usage and allocation patterns that impact IO performance are simply not predictable or reproducable from run to run. So, yeah, trying to bisect […] will not be reliable....```
https://lore.kernel.org/all/20230509071053.GE2651828@dread.disaster.area/ #LinuxKernel
Reminder: a #kernel where `uname -r` prints something like "5.15.0-71-generic" is a vendor kernel that is likely quite different from #Linux 5.15.71[1].
In case of problems with such a kernel you thus must report them to your vendor.
That's because almost all upstream #LinuxKernel developers don't care about problems in such kernels, as they might happen due to modifications the vendor applied.
[1] it in fact is likely based on a much later Linux 5.15.y release
#Linux #kernel 6.4-rc1 is out:
https://lore.kernel.org/lkml/CAHk-=wiUxm-NZ1si8dXWVTTJ9n3c+1SRTC0V+Lk7hOE4bDVwJQ@mail.gmail.com/
```Things look pretty normal […]
[…] So I'm now using the 'histogram' algorithm, […] it does occasionally cause line number differences in the diffstats […]
The diffstat is completely dominated by AMD GPU hardware description files once again, and this time the 'perf' tool has followed suite […]
The one feature that didn't make it was the x86 shadow stack code. […]
Anyway, please do go test it all out,
Linus```
Remember that story recently about Project Zero finding three unpatched kernel vulnerabilities in CentOS 9? As of May 1st, all three are now fixed (never mind the fact that one of them was already fixed well before the story came out). CentOS 9 is currently the only Enterprise Linux distro with these fixes.
Andrey Konovalov updated his #Linux #kernel exploitation collection.
https://github.com/xairy/linux-kernel-exploitation/commit/5ec0dd2837113e9199b76006391ff8e50c60425c #LinuxKernel
Today was my last day at Neo4j.
For now i will be focusing on my YT channel full time. I have many ideas for it and now that i'm free i can dedicate all my attention to showing the creative side of programming, just as i wish it had been shown to me.
I'll be doing more #rust, #kernel hacking, NVMe and SSD work and, of course, animation and art for my videos. Who knows where it'll lead?
I'll be honored if you tag along with me on this adventure. I think we'll build some pretty things.
Any #Linux #Kernel, #Debian, #GNOME, or #KDE developers out there want to help me with a project?
Let's submit these projects as #DigitalPublicGoods (DPG).
If Fedora and Drupal qualify as being made to help achieve the #UN Sustainable Development Goals, surely these projects are just as important.
Ping me directly and let's chat!
https://digitalpublicgoods.net/digital-public-goods/submission-guide/
@yosh Also, slides seem to be a bit out of date: the `Vec::try_`functions were rejected from the standard library so we moved them into a trait instead: https://github.com/microsoft/rust_fallible_vec #rust #kernel
Now freely available: The @LWN article about "The early days of Linux" from Lars Wirzenius (@liw), who "was there when Linux started":
https://lwn.net/Articles/928581/ #Linux #kernel #LinuxKernel
```I started my computer science studies at the University of Helsinki in the fall of 1988, and met Linus Torvalds, who was the other new Swedish speaking student in computer science that year. Toward the end of that first year, we had gotten access to a Unix server, and I accidentally found Usenet, […]```
Analysis of an use after free in Linux kernel
Useful for learning new things even if not exploitable
"[…] It would be good if upstream #Linux [#kernel] and distributions like you could figure out some kind of solution to keep your security fixes in sync, so that an attacker who wants to quickly find a nice memory corruption bug in CentOS/RHEL can't just find such bugs in the delta between upstream stable and your kernel. […]"
@jann in https://bugs.chromium.org/p/project-zero/issues/detail?id=2439
So @chrisjrn got it - these are from 2002-2003. The hidden spine was for this issue, January 2003 - excitedly looking forwards to that year’s releases of the new #Linux kernel and new #MySQL!
Spoiler alert: some folks would end up being on #kernel 2.6 for a loooooooooooooooooooooooooooo (breath) oooooooooong time 🤣
Sadly the dry humour @corbet used at the start of the article didn't fit into above toot, hence find it here for your pleasure:
"While the [#Linux] 6.3 #kernel has gained more support for the #Rust language, it still remains true that there is little that can be done in Rust beyond the creation of a "hello world" module. That functionality was already available in C, of course, with a level of safety similar to what Rust can provide."
My #EverythingOpen talk "An abridged history of #Linux #kernel security" is now online! https://youtu.be/LdcnxIviHuk
You should watch it. It's pretty good.
Does any of you #linux #kernel or @postmarketOS people have any idea what's going on with my #samsung #tablet when I enable #hardware #acceleration in @firefox? It seems like it renders the first few bits of text towards the top and then just stops. It works fine without hardware acceleration, but it's so much smoother with it.
The Kernel: https://github.com/msm8916-mainline/linux
I've never done kernel work, any ideas on where to start hacking?
#firefox #postmarketos #askfedi #help
Werner Fischer published a new version of his #Linux Storage Stack Diagram which now covers #Kernel 6.2:
https://www.thomas-krenn.com/en/wikiEN/index.php?title=Linux_Storage_Stack_Diagram #LinuxKernel
April 2023 issue "The Fediverse" is available now! For fastest service, buy your copy here https://bit.ly/Linux-Newsstand #Linux #Fediverse #Mastodon #diaspora #PeerTube #Pixelfed #OpenSource #SMath #authentication #FOSDEM #kernel #tools #endeavorOS #Golang #Debian #RaspberryPi #privacy
Hi #Fediverse #geeks!
I already mentioned this problem in this toot: I am getting crazy trying to solve my #webcam not working in #Linux, in particular in #Ubuntu 22.10 and #Manjaro… It works in #Windows.
I own a Lenovo ThinkPad X1 Carbon Gen 10.
Is there anything I can do?
#help #mastoaiuto #drivers #kernel #compatibility #Debian #Arch
Good morning! As you're having your morning #coffee, because this is #Naarm #Melbourne, check out @ptownpj@twitter.com upcoming talk at #EverythingOpen where PJ takes us through #irqbalance and #linux #kernel balancing.
"Interrupt Balancing: Moving beyond x86"
Example of buffer overflow in Linux kernel (6.2.0-rc1) with exploit PoC by Davide Ornaghi
(CVE-2023-0179 affecting nftables)
Someone totally crazy[1] came up with the idea to make the #Linux #kernel's checkpatch.pl raise an…
…error when it encounters unwanted tags like Bug, BugLink, or Bugzilla, as Link should be used instead
…warn if a Reported-by tag is not followed by a Link tag that points to the report
He implemented the idea with the help of his perl-capable friend Kai and the changes now landed in mainline for #Linux 6.3:
https://git.kernel.org/torvalds/c/d7f1d71e5ef630ab9e15b5821d297a9e1a5fa1da
https://git.kernel.org/torvalds/c/d7f1d71e5ef630ab9e15b5821d297a9e1a5fa1da
[1] /me is talking about himself
/me wonders at what point someone will set up a job sending the output of #Linux checkpatch.pl script in reply to every #kernel patch posted to one of its development mailing lists.
https://docs.kernel.org/dev-tools/checkpatch.html #LinuxKernel
I am incredibly stressed out since it has been two weeks now and I keep having trouble with my new #ThinkPad #X1 Carbon Gen 10.
I made the impulsive and definitely wrong decision of immediately removing #Windows and installing only @vanillaos.
There are several problems, that I cannot figure out if they are there because of #Linux #compatibility limits and absent #drivers, or rather if it is an hardware problem.
Above all, the webcam is not recognized. Like it does not even show up in /dev
Furthermore, the 2.8K screen has the PERFECT resolution for a 14" laptop, but it is OLED and it looks TERRIBLE. I hope it is only a calibration problem, but, again, I do not know how to test it…
Since #VanillaOS still has an outdated Linux #kernel, I installed #Manjaro, but upon opening #Cheese I always get “no device found”.
To increase my stress, my request to subscribe to linux.org got rejected since I signed up using a #VPN. I am losing it 😭
Please convince me not to get back to my #MacBook. I thought ThinkPads were the most Linux-ready devices!
EDIT: My specific device is this
Let's see if the simple TPM patch lands this time.
1 and a half years spent on a 3 line fix 🙃
https://lore.kernel.org/linux-integrity/20230215092552.3004363-1-morten@linderud.pw/T/#u
Linux debugging, profiling and tracing training
Great course by Bootlin
Slides: https://bootlin.com/doc/training/debugging/debugging-slides.pdf
Lab exercises: https://bootlin.com/doc/training/debugging/debugging-labs.pdf
Lab material (.tar.xz): https://bootlin.com/doc/training/debugging/debugging-labs.tar.xz
If somebody is looking for something to contribute to the #Linux #Kernel without even knowing any C: this
yes "" | make O=~/linux/build/ localmodconfig
in above document is kinda ugly; somebody should create a "localmoddefconfig" target to avoid it. Shouldn't be to hard; with a bit of luck it might be just a bit of copy and paste in a Makefile followed by a s/oldconfig/olddefconfig/ in one place and a s/localmodconfig/localmoddefconfig/ in another.
But maybe I'm wrong with that.
Posted v2 of my patch adding a text about "How to quickly build a trimmed #Linux #kernel" to the #LinuxKernel's documentation:
Rendered version:
objtool: Honey, I shrunk the instruction
That's the title peterz used for a patch-set that reduces the memory usage of an #Linux #kernel allyesconfig build by about 6G and also speeds it up by about 55 seconds in his testing.
https://lore.kernel.org/all/20230208171756.898991570@infradead.org/ #LinuxKernel
Trigger was Boris, as he "complained he could no longer build allyesconfig on his 32G desktop machine without having OOM terminate either objtool or chrome." 😂
For folks building systems with a more paranoid #Linux #kernel, do you use any "slub_debug" features beyond "slub_debug=ZF" (redzoning and verification) for security flaw #mitigations ?
e.g. "slub_debug=P" has been superseded by "init_on_alloc=1 init_on_free=1"...
The flags are listed here:
https://docs.kernel.org/mm/slub.html