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LWN.net is a comprehensive source of news and opinions from and about the Linux community. This is the main LWN.net feed, listing all articles which are posted to the site front page.
Updated: 1 hour 55 min ago

Four new stable kernels

Thursday 31st of January 2019 03:32:05 PM
Greg Kroah-Hartman has released the 4.20.6, 4.19.19, 4.14.97, and 4.9.154. These kernels contain important fixes throughout the kernel tree; users should upgrade.

Security updates for Thursday

Thursday 31st of January 2019 02:53:21 PM
Security updates have been issued by Arch Linux (ghostscript), Debian (firefox-esr, libgd2, libvncserver, php-pear, rssh, and spice), Fedora (docker, docker-latest, firefox, moodle, and wireshark), Mageia (bluez, ghostscript, php-tcpdf, phpmyadmin, virtualbox, and zeromq), openSUSE (ghostscript), Red Hat (firefox), Scientific Linux (firefox), Slackware (kernel), and Ubuntu (avahi, firefox, and openjdk-8, openjdk-lts).

[$] LWN.net Weekly Edition for January 31, 2019

Thursday 31st of January 2019 01:11:19 AM
The LWN.net Weekly Edition for January 31, 2019 is available.

[$] Design for security

Wednesday 30th of January 2019 09:01:34 PM

Serena Chen began her talk in the Security, Identity & Privacy miniconf at linux.conf.au 2019 with a plan to dispel a pervasive myth that "usability and security are mutually exclusive". She hoped that by the end of her talk, she could convince the audience that the opposite is true: good user experience design and good security cannot exist without each other. It makes sense, she said, because a secure system must be reliable and controllable, which means it must be usable, while a usable system must be less confusing, thus it is more secure.

Alpine Linux 3.9.0 Released

Wednesday 30th of January 2019 06:17:08 PM
Alpine Linux 3.9 has been released. This version features support for armv7, a switch from LibreSSL to OpenSSL, improved GRUB support, and more.

[$] An open-source artificial pancreas

Wednesday 30th of January 2019 04:02:17 PM

Dana Lewis said that her keynote at linux.conf.au 2019 would be about her journey of learning about open source and how it could be applied in the healthcare world. She hoped it might lead some attendees to use their talents on solutions for healthcare. Her efforts and those of others in the community have led to a much better quality of life for a number of those who suffer from a chronic, time-consuming disease.

Security updates for Wednesday

Wednesday 30th of January 2019 03:35:16 PM
Security updates have been issued by Arch Linux (subversion), Debian (apache2, firefox-esr, qemu, rssh, and spice), Fedora (lua, mingw-python-qt5, mingw-qt5-qt3d, mingw-qt5-qtactiveqt, mingw-qt5-qtbase, mingw-qt5-qtcharts, mingw-qt5-qtdeclarative, mingw-qt5-qtgraphicaleffects, mingw-qt5-qtimageformats, mingw-qt5-qtlocation, mingw-qt5-qtmultimedia, mingw-qt5-qtquickcontrols, mingw-qt5-qtscript, mingw-qt5-qtsensors, mingw-qt5-qtserialport, mingw-qt5-qtsvg, mingw-qt5-qttools, mingw-qt5-qttranslations, mingw-qt5-qtwebkit, mingw-qt5-qtwebsockets, mingw-qt5-qtwinextras, mingw-qt5-qtxmlpatterns, mingw-sip, nagios, and radvd), Oracle (bind, kernel, and systemd), Red Hat (bind, kernel, kernel-alt, kernel-rt, and systemd), Scientific Linux (bind, kernel, and systemd), Slackware (mozilla), SUSE (kernel, openssl-1_1, and subversion), and Ubuntu (openvswitch).

Kodi 18 is here

Tuesday 29th of January 2019 07:57:13 PM
The Kodi team has announced the release of Kodi 18.0 "Leia". "One of the big features of this release: support for gaming emulators, ROMs and controls. This is a significant topic in its own right, so look out for future posts on this, but suffice it to say at this time that you now have a whole world of retro gaming at your fingertips, all from the same interface as your movies, music and TV shows. For the genuine experience as well, we've also introduced support for joysticks, gamepads, and other platform-specific controls, so the games will work just as was intended."

Firefox 65.0 released

Tuesday 29th of January 2019 06:16:03 PM
Firefox 65.0 is out. The release notes list a few new features, including: "Enhanced tracking protection: Simplified content blocking settings give users standard, strict, and custom options to control online trackers. A redesigned content blocking section in the site information panel (viewed by expanding the small “i” icon in the address bar) shows what Firefox detects and blocks on each website you visit."

Security updates for Tuesday

Tuesday 29th of January 2019 03:42:35 PM
Security updates have been issued by Arch Linux (go-pie), Debian (wireshark), openSUSE (freerdp, libraw, openssh, pdns-recursor, singularity, and systemd), and Ubuntu (kernel, linux-hwe, and spice).

[$] Systemd as tragedy

Monday 28th of January 2019 08:05:35 PM
Tragedy, according to Wikipedia, is "a form of drama based on human suffering that invokes an accompanying catharsis or pleasure in audiences". Benno Rice took his inspiration from that definition for his 2019 linux.conf.au talk on the story of systemd which, he said, involves no shortage of suffering. His attempt to cast that story for the pleasure of his audience resulted in a sympathetic and nuanced look at a turbulent chapter in the history of the Linux system.

Security updates for Monday

Monday 28th of January 2019 03:34:48 PM
Security updates have been issued by Arch Linux (apache, go, haproxy, matrix-synapse, nasm, and powerdns-recursor), Debian (coturn, ghostscript, krb5, policykit-1, and qtbase-opensource-src), Fedora (wireshark), openSUSE (nodejs4, nodejs8, openssh, PackageKit, and wireshark), Oracle (qemu and thunderbird), Scientific Linux (thunderbird), and SUSE (avahi, krb5, and python-paramiko).

Kernel prepatch 5.0-rc4

Monday 28th of January 2019 09:16:30 AM
The 5.0-rc4 kernel prepatch is out. "Go test and report any oddities you can find, but I think we're doing fine."

Bison 3.3 released

Saturday 26th of January 2019 09:00:39 PM
Version 3.3 of the Bison parser generator is out. "The new option --update replaces deprecated features with their modern spelling, but also applies fixes such as eliminating duplicate directives, etc. It is now possible to annotate rules with their number of expected conflicts. Bison can be made relocatable. The symbol declaration syntax was overhauled, and in particular, %nterm, that exists since the origins of Bison, is now an officially supported (and documented!) feature. C++ parsers now feature genuine symbol constructors, and use noexcept/constexpr. The GLR parsers in C++ now support the syntax_error exceptions. There are also many smaller improvements, including a fix for a bug which is at least 31 years old."

A set of stable kernels for the weekend

Saturday 26th of January 2019 04:29:12 PM
Stable kernels 4.20.5, 4.19.18, 4.14.96, 4.9.153, 4.4.172, and 3.18.133 have been released. They all contain important fixes and users should upgrade.

[$] Snowpatch: continuous-integration testing for the kernel

Saturday 26th of January 2019 12:36:49 AM
Many projects use continuous-integration (CI) testing to improve the quality of the software they produce. By running a set of tests after every commit, CI systems can identify problems quickly, before they find their way into a release and bite unsuspecting users. The Linux kernel project lags many others in its use of CI testing for a number of reasons, including a fundamental mismatch with how kernel developers tend to manage their workflows. At linux.conf.au 2019, Russell Currey described a CI system called Snowpatch that, he hopes, will bridge the gap and bring better testing to the kernel development process.

MythTV 30.0 released

Friday 25th of January 2019 09:14:52 PM
The MythTV Team has announced the release of MythTV 30.0. The release notes contain more information. This version includes support for mythfrontend running on certain Android TV devices. "Over 500 commits made significant improvements to the infrastructure. For the most part, these are invisible to end users."

Security updates for Friday

Friday 25th of January 2019 03:06:32 PM
Security updates have been issued by Debian (mxml, postgresql-9.4, and tmpreaper), Fedora (haproxy and runc), openSUSE (krb5, soundtouch, virtualbox, and zeromq), Oracle (thunderbird), Red Hat (thunderbird), and Ubuntu (subversion and thunderbird).

[$] Changing the world with better documentation

Thursday 24th of January 2019 08:04:34 PM
Rory Aronson started his 2019 linux.conf.au keynote with a statement that gardening just isn't his passion; an early attempt degenerated into a weed-choked mess when he couldn't be bothered to keep it up. But he turned out to be passionate indeed about building a machine that would do the gardening for him. That led to the FarmBot project, a successful exercise in the creation of open hardware, open software, and an open business. A big part of that success, it turns out, lies in the project's documentation.

Debian 9.7 released

Thursday 24th of January 2019 07:42:20 PM
The Debian Project has announced an update to Debian 9 "stretch". "This point release incorporates the recent security update for APT, in order to help ensure that new installations of stretch are not vulnerable. No other updates are included."

More in Tux Machines

Games: Surviving Mars and OpenMW

Kernel and Security: BPF, Mesa, Embedded World, Kernel Address Sanitizer and More

  • Concurrency management in BPF
    In the beginning, programs run on the in-kernel BPF virtual machine had no persistent internal state and no data that was shared with any other part of the system. The arrival of eBPF and, in particular, its maps functionality, has changed that situation, though, since a map can be shared between two or more BPF programs as well as with processes running in user space. That sharing naturally leads to concurrency problems, so the BPF developers have found themselves needing to add primitives to manage concurrency (the "exchange and add" or XADD instruction, for example). The next step is the addition of a spinlock mechanism to protect data structures, which has also led to some wider discussions on what the BPF memory model should look like. A BPF map can be thought of as a sort of array or hash-table data structure. The actual data stored in a map can be of an arbitrary type, including structures. If a complex structure is read from a map while it is being modified, the result may be internally inconsistent, with surprising (and probably unwelcome) results. In an attempt to prevent such problems, Alexei Starovoitov introduced BPF spinlocks in mid-January; after a number of quick review cycles, version 7 of the patch set was applied on February 1. If all goes well, this feature will be included in the 5.1 kernel.
  • Intel Ready To Add Their Experimental "Iris" Gallium3D Driver To Mesa
    For just over the past year Intel open-source driver developers have been developing a new Gallium3D-based OpenGL driver for Linux systems as the eventual replacement to their long-standing "i965 classic" Mesa driver. The Intel developers are now confident enough in the state of this new driver dubbed Iris that they are looking to merge the driver into mainline Mesa proper.  The Iris Gallium3D driver has now matured enough that Kenneth Graunke, the Intel OTC developer who originally started Iris in late 2017, is looking to merge the driver into the mainline code-base of Mesa. The driver isn't yet complete but it's already in good enough shape that he's looking for it to be merged albeit marked experimental.
  • Hallo Nürnberg!
    Collabora is headed to Nuremberg, Germany next week to take part in the 2019 edition of Embedded World, "the leading international fair for embedded systems". Following a successful first attendance in 2018, we are very much looking forward to our second visit! If you are planning on attending, please come say hello in Hall 4, booth 4-280! This year, we will be showcasing a state-of-the-art infrastructure for end-to-end, embedded software production. From the birth of a software platform, to reproducible continuous builds, to automated testing on hardware, get a firsthand look at our platform building expertise and see how we use continuous integration to increase productivity and quality control in embedded Linux.
  • KASAN Spots Another Kernel Vulnerability From Early Linux 2.6 Through 4.20
    The Kernel Address Sanitizer (KASAN) that detects dynamic memory errors within the Linux kernel code has just picked up another win with uncovering a use-after-free vulnerability that's been around since the early Linux 2.6 kernels. KASAN (along with the other sanitizers) have already proven quite valuable in spotting various coding mistakes hopefully before they are exploited in the real-world. The Kernel Address Sanitizer picked up another feather in its hat with being responsible for the CVE-2019-8912 discovery.
  • io_uring, SCM_RIGHTS, and reference-count cycles
    The io_uring mechanism that was described here in January has been through a number of revisions since then; those changes have generally been fixing implementation issues rather than changing the user-space API. In particular, this patch set seems to have received more than the usual amount of security-related review, which can only be a good thing. Security concerns became a bit of an obstacle for io_uring, though, when virtual filesystem (VFS) maintainer Al Viro threatened to veto the merging of the whole thing. It turns out that there were some reference-counting issues that required his unique experience to straighten out. The VFS layer is a complicated beast; it must manage the complexities of the filesystem namespace in a way that provides the highest possible performance while maintaining security and correctness. Achieving that requires making use of almost all of the locking and concurrency-management mechanisms that the kernel offers, plus a couple more implemented internally. It is fair to say that the number of kernel developers who thoroughly understand how it works is extremely small; indeed, sometimes it seems like Viro is the only one with the full picture. In keeping with time-honored kernel tradition, little of this complexity is documented, so when Viro gets a moment to write down how some of it works, it's worth paying attention. In a long "brain dump", Viro described how file reference counts are managed, how reference-count cycles can come about, and what the kernel does to break them. For those with the time to beat their brains against it for a while, Viro's explanation (along with a few corrections) is well worth reading. For the rest of us, a lighter version follows.

Blacklisting insecure filesystems in openSUSE

The Linux kernel supports a wide variety of filesystem types, many of which have not seen significant use — or maintenance — in many years. Developers in the openSUSE project have concluded that many of these filesystem types are, at this point, more useful to attackers than to openSUSE users and are proposing to blacklist many of them by default. Such changes can be controversial, but it's probably still fair to say that few people expected the massive discussion that resulted, covering everything from the number of OS/2 users to how openSUSE fits into the distribution marketplace. On January 30, Martin Wilck started the discussion with a proposal to add a blacklist preventing the automatic loading of a set of kernel modules implementing (mostly) old filesystems. These include filesystems like JFS, Minix, cramfs, AFFS, and F2FS. For most of these, the logic is that the filesystems are essentially unused and the modules implementing them have seen little maintenance in recent decades. But those modules can still be automatically loaded if a user inserts a removable drive containing one of those filesystem types. There are a number of fuzz-testing efforts underway in the kernel community, but it seems relatively unlikely that any of them are targeting, say, FreeVxFS filesystem images. So it is not unreasonable to suspect that there just might be exploitable bugs in those modules. Preventing modules for ancient, unmaintained filesystems from automatically loading may thus protect some users against flash-drive attacks. If there were to be a fight over a proposal like this, one would ordinarily expect it to be concerned with the specific list of unwelcome modules. But there was relatively little of that. One possible exception is F2FS, the presence of which raised some eyebrows since it is under active development, having received 44 changes in the 5.0 development cycle, for example. Interestingly, it turns out that openSUSE stopped shipping F2FS in September. While the filesystem is being actively developed, it seems that, with rare exceptions, nobody is actively backporting fixes, and the filesystem also lacks a mechanism to prevent an old F2FS implementation from being confused by a filesystem created by a newer version. Rather than deal with these issues, openSUSE decided to just drop the filesystem altogether. As it happens, the blacklist proposal looks likely to allow F2FS to return to the distribution since it can be blacklisted by default. Read more

gitgeist: a git-based social network proof of concept

Are you tired of not owning the data or the platform you use for social postings? I know I am. It's hard to say when I "first" used a social network. I've been on email for about 30 years and one of the early ad-hoc forms of social networks were chain emails. Over the years I was asked to join all sorts of "social" things such as IRC, ICQ, Skype, MSN Messenger, etc. and eventually things like Orkut, MySpace, Facebook, etc. I'll readily admit that I'm not the type of person that happily jumps onto every new social bandwagon that appears on the Internet. I often prefer preserving the quietness of my own thoughts. That, though, hasn't stopped me from finding some meaningfulness participating in Twitter, Facebook, LinkedIn and more recently Google+. Twitter was in fact the first social network that I truly embraced. And it would've remained my primary social network had they not killed their own community by culling the swell of independently-developed Twitter clients that existed. That and their increased control of their API effectively made me look for something else. Right around that time Google+ was being introduced and many in the open source community started participating in that, in some ways to find a fresh place where techies can aggregate away from the noise and sometimes over-the-top nature of Facebook. Eventually I took to that too and started using G+ as my primary social network. That is, until Google recently decided to pull the plug on G+. While Google+ might not have represented a success for Google, it had become a good place for sharing information among the technically-inclined. As such, I found it quite useful for learning and hearing about new things in my field. Soon-to-be-former users of G+ have gone in all sorts of directions. Some have adopted a "c'mon guys, get over it, Facebook is the spot" attitude, others have adopted things like Mastodon, others have fallen back to their existing IDs on Twitter, and yet others, like me, are still looking. Read more