Linux Weekly News

Security updates have been issued by Debian (node-cipher-base), Fedora (keylime-agent-rust and libtiff), Oracle (aide, kernel, mod_http2, pam, pki-deps:10.6, python-cryptography, python3, python3.12, and thunderbird), SUSE (cheat, ffmpeg, firebird, govulncheck-vulndb, postgresql17, tomcat, tomcat10, tomcat11, ucode-intel-20250812, and v2ray-core), and Ubuntu (binutils, gst-plugins-base1.0, gst-plugins-good1.0, and linux-raspi-realtime).

Shadow stacks are a control-flow-integrity feature designed to defend against exploits that manipulate a thread's call stack. The kernel first gained support for hardware-implemented shadow stacks, for the x86 architecture, in the 6.6 release; 64-bit Arm support followed in 6.13. This feature does not give user space much control over the allocation of shadow stacks for new threads, though; a patch series from Mark Brown may, after many attempts, finally be about to change that situation.

Security updates have been issued by Debian (ffmpeg, firebird3.0, and luajit), Fedora (chromium, python3-docs, and python3.13), Oracle (aide, firefox, glibc, libxml2, and tomcat), Red Hat (aide, git, kernel, kernel-rt, libarchive, pam, python-cryptography, python3, python3.12, and webkit2gtk3), SUSE (cmake3, ffmpeg-4, kernel, kubernetes1.18, libqt4, minikube, net-tools, pam, postgresql16, proftpd, python-urllib3, python311, python312, python36, tomcat10, tomcat11, and webkit2gtk3), and Ubuntu (nginx).

Google has announced a new set of restrictions on the ability of users to install apps on their own devices:

Starting next year, Android will require all apps to be registered by verified developers in order to be installed by users on certified Android devices. This creates crucial accountability, making it much harder for malicious actors to quickly distribute another harmful app after we take the first one down. Think of it like an ID check at the airport, which confirms a traveler's identity but is separate from the security screening of their bags; we will be confirming who the developer is, not reviewing the content of their app or where it came from.

The PyCon team has announced that all PyCon US 2025 recordings are now available on its YouTube channel.

We had an amazing and diverse group of community members join us for PyCon US 2025, attending from 58 different countries! By the numbers, we welcomed a total attendance of 2,225 Pythonistas to the David L. Lawrence Convention Center. We couldn't be more grateful for all who supported the Python ecosystem and helped make PyCon US 2025 a huge success.

See the LWN conference index for coverage of some of the talks from PyCon US 2025.

In July 2024, Let's Encrypt, the nonprofit TLS certificate authority (CA), announced that it would be ending support for the online certificate status protocol (OCSP), which is used to determine when a server's signing certificate has been revoked. This prevents a compromised key from being used to impersonate a web server. The organization cited privacy concerns, and recommended that people rely on certificate revocation lists (CRLs) instead. On August 6, Let's Encrypt followed through and disabled its OCSP service. This poses a problem for Linux systems that must now rely on CRLs because, unlike on other operating systems, there is no standardized way for Linux programs to share a CRL cache.

The Linux Foundation, in cooperation with a couple of other groups, has announced the publication on the intersection of businesses and commercial open-source software (deemed "COSS"). Everything, it seems, is great, and COSS companies make a lot of money for their investors.

Even more encouraging, COSS project communities continue along healthy growth paths after the company receives venture funding. In essence, highly valued COSS companies tend to cultivate more vibrant, diverse, and integral open source ecosystems, reinforcing the idea that business value and community value are tightly coupled in successful COSS models.

Security updates have been issued by AlmaLinux (kernel and tomcat9), Debian (iperf3, mupdf, qemu, thunderbird, and unbound), Fedora (glab, kubernetes1.31, kubernetes1.32, kubernetes1.33, and toolbox), Oracle (kernel and tomcat9), Red Hat (firefox, kernel, kernel-rt, and squid), SUSE (abseil-cpp-devel, aide, flake-pilot, gdk-pixbuf, glibc, go-sendxmpp, ImageMagick, jetty-annotations, jupyter-bqplot-jupyterlab, libtiff-devel-32bit, pam, pdns-recursor, ruby3.4-rubygem-activerecord, rust-keylime, terragrunt, and thunderbird), and Ubuntu (linux-azure and linux-azure-fips).

Linus has released 6.17-rc3 (called "3.17-rc3" in the email, but the tag in the repository is correct) for testing. "Anyway, things seem fairly normal for this phase in the release cycle, nothing stands out. Please keep testing,"

The 6.16.3 stable kernel update has been released. It contains a set of ext4 filesystem fixes that are probably a good thing for any 6.16 ext4 user to have.

Version 8.0 of the FFmpeg audio and video toolkit has been released.

Thanks to several delays, and modernization of our entire infrastructure, this release ended up being one of our largest releases to date. In short, its new features are:

• Native decoders: APV, ProRes RAW, RealVideo 6.0, Sanyo LD-ADPCM, G.728
• VVC decoder improvements: IBC, ACT, Palette Mode
• Vulkan compute-based codecs: FFv1 (encode and decode), ProRes RAW (decode only)
• Hardware accelerated decoding: Vulkan VP9, VAAPI VVC, OpenHarmony H264/5
• Hardware accelerated encoding: Vulkan AV1, OpenHarmony H264/5
• Formats: MCC, G.728, Whip, APV
• Filters: colordetect, pad_cuda, scale_d3d11, Whisper, and others

The Microdot web framework is quite small, as its name would imply; it supports both standard CPython and MicroPython, so it can be used on systems ranging from internet-of-things (IoT) devices all the way up to large, cloudy servers. It was developed by Miguel Grinberg, who gave a presentation about it at EuroPython 2025. His name may sound familiar from his well-known Flask Mega-Tutorial, which has introduced many to the Flask lightweight Python-based web framework. It should come as no surprise, then, that Microdot is inspired by its rather larger cousin, so Flask enthusiasts will find much to like in Microdot—and will come up to speed quickly should their needs turn toward smaller systems.

Security updates have been issued by AlmaLinux (tomcat), Debian (squid), Fedora (matrix-synapse, rust-slab, socat, and webkitgtk), SUSE (firefox-esr, gdk-pixbuf, gdk-pixbuf-devel, govulncheck-vulndb, rust-keylime, and wicked2nm), and Ubuntu (linux-nvidia, linux-oracle, linux-oracle-6.8, php7.0, php7.2, php7.4, python3.13, python3.12, python3.11, python3.10, python3.9, python3.8, python3.7, python3.6, python3.5, python3.4, and ruby-webrick).

The Arch Linux project has posted an update about recent service outages that have affected its infrastructure:

The Arch Linux Project is currently experiencing an ongoing denial of service attack that primarily impacts our main webpage, the Arch User Repository (AUR), and the Forums.

We are aware of the problems that this creates for our end users and will continue to actively work with our hosting provider to mitigate the attack. We are also evaluating DDoS protection providers while carefully considering factors including cost, security, and ethical standards.

The post contains information on workarounds to use during the service disruption, and notes that Arch is not sharing technical details about the attack or mitigation while the attack is still ongoing.

The restartable sequences feature, which was added to the 4.18 kernel in 2018, exists to enable better performance in certain types of threaded applications. While there are users for restartable sequences, they tend to be relatively specialized code; this is not a tool that most application developers reach for. Over time, though, the use of restartable sequences has grown, and it looks to grow further as the feature is tied to new capabilities provided by the kernel. As restartable sequences become less of a niche feature, though, some problems have turned up; fixing one of them may involve an ABI change visible in user space.

Security updates have been issued by AlmaLinux (libarchive, mingw-sqlite, pki-deps:10.6, and tomcat), Debian (chromium and firefox-esr), Fedora (python3.6 and suricata), Oracle (go-toolset:rhel8, kernel, libarchive, mingw-sqlite, tomcat, and xterm), Red Hat (kernel), Slackware (mozilla), SUSE (aws-efs-utils, docker-machine-driver-kvm2, nova, pluto, polaris, and python310), and Ubuntu (ceph, gcc-10, gcc-11, gcc-12, linux-aws-6.8, linux-gcp, linux-gcp-6.8, linux-gkeop, linux-ibm, linux-ibm-6.8, linux-hwe-6.14, linux-oem-6.14, linux-ibm, linux-intel-iotg, linux-oracle, linux-raspi, linux-iot, poppler, and tiff).

Inside this week's LWN.net Weekly Edition:

• Front: Debian; CPython; huge zero folio; kexec handover; FHS; Koka programming language
• Briefs: PyPI domain checks; Firefox 142.0; Git v2.51; Ghostty; LibreOffice 25.8; Zig 0.15.1; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

The Zig project has announced version 0.15.1 of the language. The release, much like the last one, includes incremental progress toward the goal of completely dropping LLVM and improving compile time, as well as a handful of breaking changes as the language team wrestles with past API design. The biggest change this time around is to the standard library Reader and Writer interfaces, which have been completely rearranged in the name of performance and reducing unneeded copies.

All existing std.io readers and writers are deprecated in favor of the newly provided std.Io.Reader and std.Io.Writer which are non-generic and have the buffer above the vtable - in other words the buffer is in the interface, not the implementation. This means that although Reader and Writer are no longer generic, they are still transparent to optimization; all of the interface functions have a concrete hot path operating on the buffer, and only make vtable calls when the buffer is full.

These changes are extremely breaking. I am sorry for that, but I have carefully examined the situation and acquired confidence that this is the direction that Zig needs to go. I hope you will strap in your seatbelt and come along for the ride; it will be worth it.

Tobias Heider has written an article that explains changes that are coming for Ubuntu's generic Arm64 desktop ISO images in the 25.10 release. The current solution, Heider says, depends on GRUB features that are unavailable in secure boot mode and require adding device-specific logic to multiple packages. The new solution, called stubble, is derived from systemd-stub:

A bundled stubble image contains stubble itself, a Linux kernel, a HWID lookup table to map devices to device trees and multiple device trees. When grub loads this "kernel", stubble executes first, reads the SMBIOS table to generate HWIDs, looks for a match in the embeeded lookup table and loads a matching device tree before passing control to the actual Linux kernel.

The elegance in this approach lies in how it interacts with the rest of the system. Integrating stubble happens entirely at build time in the kernel package. The stubble package is a build dependency for the kernel. After building the kernel itself, we bundle it with stubble and our DTBs and ship the combined binary instead. The resulting stubble + kernel + dtb bundle can be loaded by grub like any other Ubuntu kernel. No further changes in grub or other packages are necessary to make it work.

Greg Kroah-Hartman has announced the release of the 6.16.2, 6.15.11, and 6.12.43 stable kernels. He notes that this is the last release in the 6.15.y series, and recommends that users move to the 6.16.y kernel branch at this time.