Linux Weekly News

Security updates have been issued by Debian (dcmtk, geographiclib, gimp, pure-ftpd, and ruby-rack), Fedora (dotnet9.0), Oracle (expat, kernel, tigervnc, xorg-x11-server, and xorg-x11-server-Xwayland), Red Hat (git, mariadb:10.5, multiple packages, osbuild-composer, pcs, sssd, and tigervnc), SUSE (kernel and redis), and Ubuntu (google-guest-agent).

Version 1.0 of the Capability Hardware Extension to RISC-V for IoT (CHERIoT) specification has been released. CHERIoT is a hardware-software system for secure embedded devices, and the specification provides a full description of the ISA and its intended use by CHERIoT RTOS. David Chisnall has written a blog post about the release that explains its significance as well as plans for CHERIoT 2.0 and beyond:

The last change that we made to the ISA was in December 2024, so we are confident that this is a stable release that we can support in hardware for a long time. This specification was implemented by the 1.0 release of CHERIoT Ibex and by CHERIoT Kudu (which has not yet had an official release). These two implementations demonstrate that the ISA scales from three-stage single-issue pipelines to six-stage dual-issue pipelines, roughly the same range of microarchitectures supported by Arm's M profile.

We at SCI have the first of our ICENI chips, which use the CHERIoT Ibex core, on the way back from the fab now and will be scaling up to mass production in the new year. I am not allowed to speak for other folks building CHERIoT silicon, but I expect 2026 to be an exciting year for the CHERIoT project!

The Project Zero blog explains that, on 64-bit Arm systems, the kernel's direct map is always placed at the same virtual location, regardless of whether kernel address-space layout randomization (KASLR) is enabled.

While it remains true that KASLR should not be trusted to prevent exploitation, particularly in local contexts, it is regrettable that the attitude around Linux KASLR is so fatalistic that putting in the engineering effort to preserve its remaining integrity is not considered to be worthwhile. The joint effect of these two issues dramatically simplified what might otherwise have been a more complicated and likely less reliable exploit.