Linux Weekly News

Inside this week's LWN.net Weekly Edition:

• Front: Fedora AI; Forgejo "carrot" disclosure; memory-management maintainership; huge THPs; mshare; 64KB base pages; DAMON; direct map.
• Briefs: Dirty Frag; Fragnesia; Mythos and curl; killswitch; Debian reproducible builds; KDE investment; Quotes ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

A push by Red Hat employees to create a Fedora "AI Developer Desktop" with support for out-of-tree kernel drivers and AI toolkits has been met with objections from some long-time members of the Fedora community. After more than a month of sometimes heated discussion, the Fedora Council had voted to approve the initiative; however, a last-minute change to vote against the proposal by council member Justin Wheeler has (at least temporarily) sent it back to the drawing board.

Sam James has sent an announcement to the OSS Security mailing list about another local-privilege-escalation (LPE) exploit in the same class as Dirty Frag, called "Fragnesia". From the disclosure:

This is a separate bug in the ESP/XFRM from dirtyfrag which has received its own patch. However, it is in the same surface and the mitigation is the same as for dirtyfrag.

It abuses a logic bug in the Linux XFRM ESP-in-TCP subsystem to achieve arbitrary byte writes into the kernel page cache of read-only files, without requiring any race condition.

James noted that there is a patch in the works, but it has not yet been pulled into Linus Torvalds's tree nor into any of the stable kernels. A proof of concept exploit is also available.

When Brendan Jackman proposed a session for the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, his topic was "a pagetable library for the kernel". During the actual memory-management-track session, though, he stated that the idea had "fizzled" and he was going to cover related topics instead. What resulted was a session on ways to efficiently manage pages that are not present in the kernel's direct map.

Linux can share memory between processes, but each process (almost always) has its own set of page tables. In situations where vast numbers of processes are sharing a memory region, the combined size of the page tables can exceed that of the shared memory itself. There has, thus, long been an interest in enabling unrelated processes to share page tables referring to shared memory. Anthony Yznaga is the latest developer to try to push this idea (known as "mshare") forward; he described the status of that work in a memory-management-track discussion at the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit (LSFMM+BPF).

Security updates have been issued by AlmaLinux (corosync, freerdp, git-lfs, glib2, jq, kernel-rt, krb5, libpng, libtiff, openexr, and thunderbird), Debian (exim4), Mageia (apache, perl-Gazelle, php, and sed), Slackware (expat), SUSE (assimp-devel, go1.26, libQt6Svg6, python-jupyterlab, raylib, thunderbird, tor, and trivy), and Ubuntu (exim4).

The KDE project has announced that it has been awarded over €1 million from the Sovereign Tech Fund to improve its desktop-environment software. "The investment will be used to strengthen the structural reliability and security of KDE's core infrastructure, including Plasma, KDE Linux, and the frameworks underlying its communication services."

The kernel's dma-buf subsystem provides a way for drivers to share memory buffers, usually in order to support efficient device-to-device I/O. At the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, Pavel Begunkov, assisted by Kanchan Joshi, led a joint session of the storage and memory-management tracks to explore ways to make the use of dma-bufs more efficient yet, and to make them available for read and write operations initiated by user space.

As a general rule, when developers talk about huge pages, they are referring to PMD-level pages that are 1MB or 2MB in size, depending on the CPU architecture. Most CPUs can support other huge-page sizes, though. On x86 systems, PUD-level huge pages hold 1GB of data. Providing such large pages transparently to processes has generally not been considered as either feasible or desirable, but Usama Arif is trying to change that assessment. At the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, he led a session in the memory-management track on how to make transparent huge pages (THPs) truly huge.

Security updates have been issued by AlmaLinux (freerdp, glib2, libsoup3, and openexr), Debian (dnsmasq, p7zip, p7zip-rar, python-authlib, and rails), Fedora (chromium, firefox, httpd, and nss), SUSE (java-25-openj9, krb5, libmodsecurity3, and mcphost), and Ubuntu (imagemagick, linux, linux-aws, linux-aws-fips, linux-aws-hwe, linux-azure-4.15, linux-fips, linux-gcp, linux-gcp-4.15, linux-gcp-fips, linux-hwe, linux-kvm, linux-oracle, linux-azure, linux-azure-fips, linux-oracle, linux-azure-5.15, linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency, and linux-raspi).

Daniel Stenberg has published a lengthy article on his thoughts on Anthropic's Mythos, which the company decided was too dangerous for wide public release.

My personal conclusion can however not end up with anything else than that the big hype around this model so far was primarily marketing. I see no evidence that this setup finds issues to any particular higher or more advanced degree than the other tools have done before Mythos. Maybe this model is a little bit better, but even if it is, it is not better to a degree that seems to make a significant dent in code analyzing.

This is just one source code repository and maybe it is much better on other things. I can only tell and comment on what it found here.

But allow me to highlight and reiterate what I have said before: AI powered code analyzers are significantly better at finding security flaws and mistakes in source code than any traditional code analyzers did in the past. All modern AI models are good at this now. Anyone with time and some experimental spirits can find security problems now. The high quality chaos is real.

Greg Kroah-Hartman has released the 7.0.6 and 6.18.29 stable kernels with Hyunwoo Kim's patch for the second vulnerability (CVE-2026-43500) reported with Dirty Frag and Copy Fail 2. All users are advised to upgrade.

Some CPU architectures are able to run with a number of different base-page sizes; using a larger size can often result in better performance at the cost of increased memory use. Other architectures are more limited. At the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, two sessions in the memory-management track explored options for letting processes run with 64KB page sizes when the underlying kernel does not. The first was focused on letting each process have its own page size, while the second concerned bringing 64KB pages to x86 systems.

Paul Gevers has slipped an interesting bit of news into a "bits from the release team" message:

Aided by the efforts of the Reproducible Builds project, we've decided it's time to say that Debian must ship reproducible packages. Since yesterday, we have enabled our migration software to block migration of new packages that can't be reproduced or existing packages (in testing) that regress in reproducibility.

As Gioele Barabucci pointed out, "reproducible" in this sense is limited to building within an instance of Debian's build environment, which is a tighter requirement than is normally used. It is still a big step forward for reproducible builds.

Security updates have been issued by AlmaLinux (corosync, freeipmi, kernel, and kernel-rt), Debian (corosync, firefox-esr, kernel, lcms2, libpng1.6, linux-6.1, php8.2, php8.4, postorius, pyjwt, and tor), Fedora (dotnet10.0, exim, gnutls, kernel, nextcloud, nodejs22, php, proftpd, prosody, python-pulp-glue, python-requests, rclone, and SDL3_image), Mageia (firefox, nss, rootcerts, openvpn, thunderbird, and vim), Oracle (corosync, freeipmi, gstreamer1-plugins-bad-free, gstreamer1-plugins-base, and gstreamer1-plugins-good, kernel, libpng, and mingw-libtiff), Slackware (kernel and mozilla), SUSE (build, product-composer, c-ares, cairo, copacetic, distribution, firefox, firefox-esr, frr, glibc, go1.25, google-cloud-sap-agent, iproute2, java-11-openj9, java-17-openj9, java-17-openjdk, java-1_8_0-openj9, java-21-openj9, java-21-openjdk, java-25-openjdk, kernel, libexif-devel, libpcp-devel, libtpms, libtree-sitter0_26, Mesa, micropython, mozjs128, nginx, opencc, openCryptoki, php-composer2, podman, postfix, python-pytest, python311-Django, python311-Django4, redis, semaphore, strongswan, terraform-provider-aws, terraform-provider-azurerm, terraform-provider-external, terraform-provider-google, terraform-provider-helm, terraform-provider-kubernetes, terraform-provid, tor, valkey, vim, and wireshark), and Ubuntu (linux-nvidia-tegra, linux-raspi, linux-raspi-5.4, and nasm).

Linus has released 7.1-rc3 for testing. "I think this answers the 'is 7.1 continuing the larger size pattern that we saw with 7.0?' question, and the answer is yes: that wasn't a fluke brought on by a .0 release - it simply seems to be the new normal."

Greg Kroah-Hartman has released the 6.1.171, 5.15.205, and 5.10.255 stable kernels, quickly followed by 6.1.172 and 5.15.206 kernels. This is another round of stable kernels to provide fixes for one of the CVEs (CVE-2026-43284) assigned following the Dirty Frag and Copy Fail 2 security disclosures. There is not, yet, a stable kernel with a fix for CVE-2026-43500, though a patch to fix the second half is in the works.

An unusual, some might say hostile, approach to disclosing an alleged remote-code-execution (RCE) flaw in the Forgejo software-collaboration platform has sparked a multifaceted conversation. A so-called "carrot disclosure" in April has raised questions about the researcher's methods of unveiling a security problem, Forgejo's security policies, and the project's overall security posture.

It seems that we are in for an extended period of the disclosure of vulnerabilities before fixes become available. One possible way of coping with this flood might be the killswitch proposal from Sasha Levin. In short, killswitch can immediately disable access to specific functionality in a running kernel, essentially blasting a vulnerable path (and its associated functionality) out of existence until a fix can be installed. "For most users, the cost of 'this socket family stops working for the day' is much smaller than the cost of running a known vulnerable kernel until the fix land."

The kernel's DAMON subsystem provides user-space monitoring and management of system memory. DAMON is developing rapidly, so an update on its progress has become a regular feature of the annual Linux Storage, Filesystem, Memory Management, and BPF Summit. This tradition continued at the 2026 gathering with an update from DAMON creator SeongJae Park covering a long list of new capabilities — tiering, data attributes monitoring, transparent huge pages, and more — being added to this subsystem.