lwn.net

Security updates for Wednesday
[$] A look at what's possible with BPF arenas
BPF arenas are areas of memory where the verifier can safely relax its checking of pointers, allowing programmers to write arbitrary data structures in BPF. Emil Tsalapatis reported on how his team has used arenas in writing sched_ext schedulers at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit. His biggest complaint was about the fact that kernel pointers can't be stored in BPF arenas — something that the BPF developers hope to address, although there are some implementation problems that must be sorted out first.
Nextcloud claims Google is being anticompetitive
Nextcloud provides an open-source collaboration platform called Nextcloud Hub, which includes file-sharing and syncing features. The company has written a blog post explaining that Google has revoked a critical permission from the Nextcloud Files app for Android that allows it to sync files to Nextcloud Hub.
Google is stating security concerns as a reason for revoking the permission. This is hard to believe for us. Nextcloud has had this feature since its inception in 2016, and we have never heard about any security concerns from Google about it. Moreover, several Big Tech apps as well as Google's own still have this. What we think: Google owning the platform means they can and are giving themselves preferential treatment.
Despite multiple appeals since mid-2024, Google has refused to reinstate the permission, blocking automated Nextcloud file uploads for millions of users.
The Nextcloud app available via F-Droid does not have this limitation, but the post notes that that is not an option for many users.
Security updates for Tuesday
Multiple security issues in Screen
The SUSE Security Team has published an article detailing several security issues it has uncovered with GNU Screen. This includes a local root exploit when Screen is shipped setuid-root, as it is in some Linux and BSD distributions. The security team also reports problems in coordinating disclosure with the upstream Screen project.
We are not satisfied with how this coordinated disclosure developed, and we will try to be more attentive to such problematic situations early on in the future. This experience also sheds light on the overall situation of Screen upstream. It looks like it suffers from a lack of manpower and expertise, which is worrying for such a widespread open source utility. We hope this publication can help to draw attention to this and to improve this situation in the future.The article includes a table of operating systems, screen versions, and which vulnerabilities they may be affected by.
Guix project migrating to Codeberg
The Guix project has announced that it is migrating all of its Git repositories, as well as bug tracking and patch tracking, from Savannah to the Codeberg Git forge.
As a user, the main change is that your channels.scm configuration files, if they refer to the git.savannah.gnu.org URL, should be changed to refer to https://codeberg.org/guix/guix.git once migration is complete. But don't worry: guix pull will tell you if/when you need to update your config files and the old URL will remain a mirror for at least a year anyway.The motivation for the move, which is spelled out in a Guix Consensus Document (GCD), is to improve the contribution experience and improve quality assurance efforts. Migration of Git repositories should be completed by June 7, though they will continue to be mirrored on Savannah until "at least" May 2026. LWN covered Guix in February 2024.
[$] The last of YaST?
The announcement of the openSUSE Leap 16.0 beta contained something of a surprise—along with the usual set of changes and updates, it informed the community of the retirement of "the traditional YaST stack" from Leap. The YaST ("Yet another Setup Tool") installation and configuration utility has been a core part of the openSUSE distribution since its inception in 2005, and part of SUSE Linux since 1996. It will not, immediately, be removed from the openSUSE Tumbleweed rolling-release distribution, but its future is uncertain and its fate is up to the larger community to decide.
Security updates for Monday
Kernel prepatch 6.15-rc6
Everything still looks fairly normal - we've got a bit more commits than we did in rc5, which isn't the trend I want to see as the release progresses, but the difference isn't all that big and it feels more like just the normal noise in timing fluctuation in pull requests of fixes than any real signal.
So I won't worry about it. We've got another two weeks to go in the normal release schedule, and it still feels like everything is on track.