Linus has released the 6.9 kernel. "So 6.9 is now out, and last week has looked quite stable (and the whole release has felt pretty normal)." Significant changes in this release include the ability to create pidfds for individual threads, the BPF arena subsystem, the BPF token security mechanism, truncate() support in io_uring, support for the Rust language on 64-bit Arm systems, weighted interleaving in the memory-management subsystem, the device-mapper virtual data optimizer target, initial FUSE passthrough support, and more. See the LWN merge-window summaries (part 1, part 2) for more information.

The extensible scheduler class (or "sched_ext") is a comprehensive framework that enables the implementation of CPU schedulers as a set of BPF programs that can be loaded at run time. Despite having attracted a fair amount of interest from the development community, sched_ext has run into considerable opposition and seems far from acceptance into the mainline. The posting by Tejun Heo of a new version of the sched_ext series at the beginning of May has restarted this long-running discussion, but it is not clear what the end result will be.

The LWN.net Weekly Edition for May 9, 2024 is available.

Version 14.1 of the GCC compiler suite has been released. The list of changes is long; it includes support for more C++26 features, preparation for Fortran 2023 support, a new -fhardened flag to enable security-hardening features, vectorizer improvements, and a number of static-analyzer improvements. See the release notes for details.

The Go Blog has a detailed article on the new, more secure random-number generator implemented for the 1.22 release.

For example, when Go 1.20 deprecated math/rand's Read, we heard from developers who discovered (thanks to tooling pointing out use of deprecated functionality) they had been using it in places where crypto/rand's Read was definitely needed, like generating key material. Using Go 1.20, that mistake is a serious security problem that merits a detailed investigation to understand the damage. Where were the keys used? How were the keys exposed? Were other random outputs exposed that might allow an attacker to derive the keys? And so on. Using Go 1.22, that mistake is just a mistake.

Security updates have been issued by Debian (kernel), Gentoo (libjpeg-turbo, xar, and Xpdf), Red Hat (bind, dhcp and glibc), and SUSE (bouncycastle, curl, flatpak, less, and xen).

The Free Software Foundation has announced the recipients of its 2023 Free Software Awards: Bruno Haible for work on gnulib, Nick Logozzo as the "outstanding new free software contributior", and code.gouv.fr for projects of social benefit.

When presenting the award to Haible, FSF executive director Zoë Kooyman commented on the significance of Haible's work, saying that Haible's work enabled free software programmers around the world to focus on the main, innovative portions of their program, thus facilitating the development of more and more free software.

The 6.9-rc7 kernel prepatch is out for testing. "The stats for 6.9 continue to look very normal, and nothing looks particularly alarming."

Kernel developers are encouraged to send their changes in small batches as a way of making life easier for reviewers. So when a longtime developer and maintainer hits the list with a 437-patch series touching 859 files, eyebrows are certain to head skyward. Specifically, this series from Jens Axboe is cleaning up one of the core abstractions that has been part of the Linux kernel almost since the beginning; authors of device drivers (among others) will have to take note.

In Unix-like systems, an open file descriptor carries the right to access the opened object in specific ways. As a general rule, that file descriptor does not enable access to any other objects. The recently merged BPF token feature runs counter to this practice by creating file descriptors that carry specific BPF-related access rights. A similar but different approach to capability-carrying file descriptors, in the form of directory file descriptors that include their own credentials, is currently under consideration in the kernel community.

Version 1.78.0 of the Rust language has been released. Changes include a new mechanism for diagnostic attributes, changes to how assertions around unsafe blocks are handled, and more.

Rust now supports a #[diagnostic] attribute namespace to influence compiler error messages. These are treated as hints which the compiler is not required to use, and it is also not an error to provide a diagnostic that the compiler doesn't recognize. This flexibility allows source code to provide diagnostics even when they're not supported by all compilers, whether those are different versions or entirely different implementations.

Version 5.0 of the Yocto Project distribution builder has been released. The list of new features is long; see the release notes for the details.

This Mastodon stream from Lennart Poettering describes a sudo replacement — called run0 — that will be part of the upcoming systemd 256 release. It takes a rather different approach to the execution of privileged commands, avoiding the use of setuid (which he calls "SUID") permissions entirely.

So, in my ideal world, we'd have an OS entirely without SUID. Let's throw out the concept of SUID on the dump of UNIX' bad ideas. An execution context for privileged code that is half under the control of unprivileged code and that needs careful manual clean-up is just not how security engineering should be done in 2024 anymore.

Version 2.45.0 of the Git source-code management system has been released. Changes include a new list command for git reflog, a couple of new configuration variables for git diff, the ability to drop redundant commits while cherry-picking, a number of performance improvements, and more.

Security updates have been issued by Debian (org-mode), Oracle (shim and tigervnc), Red Hat (ansible-core, avahi, buildah, container-tools:4.0, containernetworking-plugins, edk2, exfatprogs, fence-agents, file, freeglut, freerdp, frr, grub2, gstreamer1-plugins-bad-free, gstreamer1-plugins-base, gstreamer1-plugins-good, harfbuzz, httpd, ipa, kernel, libjpeg-turbo, libnbd, LibRaw, libsndfile, libssh, libtiff, libvirt, libX11, libXpm, mingw components, mingw-glib2, mingw-pixman, mod_http2, mod_jk and mod_proxy_cluster, motif, mutt, openssl and openssl-fips-provider, osbuild and osbuild-composer, pam, pcp, pcs, perl, pmix, podman, python-jinja2, python3.11, python3.11-cryptography, python3.11-urllib3, qemu-kvm, qt5-qtbase, runc, skopeo, squashfs-tools, systemd, tcpdump, tigervnc, toolbox, traceroute, webkit2gtk3, wpa_supplicant, xorg-x11-server, xorg-x11-server-Xwayland, and zziplib), SUSE (docker, ffmpeg, ffmpeg-4, frr, and kernel), and Ubuntu (anope, freerdp3, and php7.0, php7.2, php7.4, php8.1).

Robert McQueen has posted a message from the GNOME Foundation board describing the current financial situation, plans to improve it, and an increase in the size of the board.

The Foundation has a reserves policy which specifies a minimum amount of money we have to keep in our accounts. This is so that if there is a significant interruption to our usual income, we can preserve our core operations while we work on new funding sources. We've now "hit the buffers" of this reserves policy, meaning the Board can't approve any more deficit budgets – to keep spending at the same level we must increase our income.

The 6.9-rc6 kernel prepatch is out for testing.

Things continue to look pretty normal, and nothing here really stands out. The biggest single change that stands out in the diffstat is literally a documentation update, everything else looks pretty small and spread out.

The 6.8.8, 6.6.29, 6.1.88, and 5.15.157 stable kernels have been released; each contains another set of important fixes.

Update: 6.1.89 was released two days later to fix a build problem in 6.1.88.

Video playback is undeniably one of the most important features in modern consumer devices. Yet, surprisingly, users are by and large unaware of the intricate engineering involved in the compression and decompression of video data, with codecs being left to find a delicate balance between image quality, bandwidth, and power consumption. In response to constant performance pressure, video codecs have become complex and hardware implementations are now common, but programming these devices is becoming increasingly difficult and fraught with opportunities for exploitation. I hope to convey how Rust can help fix this problem.