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A set of patches has just been pushed into the mainline repository (and stable updates) for yet another set of hardware vulnerabilities. "TSX async abort" (or TAA) exposes information through the usual side channels by way of internal buffers used with the transactional memory (TSX) instructions. Mitigation is done by disabling TSX or by clearing the relevant buffers when switching between kernel and user mode. Given that this is not the first problem with TSX, disabling it entirely is recommended; a microcode update may be needed to do so, though. This commit contains documentation on this vulnerability and its mitigation.

There are also fixes for another vulnerability: it seems that accessing a memory address immediately after the size of the page containing it was changed (from a regular to a huge page, for example) can cause the processor to lock up. This behavior is considered undesirable by many. The vulnerability only exists for pages marked as executable; the mitigation is to force all executable pages to be the regular, 4K page size.

Stable kernels 5.3.11, 4.19.84, 4.14.154, 4.9.201, and 4.4.201 have been released. They all contain important fixes and users should upgrade.

Security updates have been issued by Fedora (community-mysql, crun, java-latest-openjdk, and mupdf), openSUSE (libssh2_org), and SUSE (go1.12, libseccomp, and tar).

Many community-based Linux distributions have made the decision to switch to systemd, and most of those decisions were accompanied by lengthy, sometimes acrimonious mailing-list discussions. No distribution had a harder time of it than Debian, though, where arguments raged through much of 2013 before the Debian Technical Committee decided on systemd in early 2014. Thereafter, it is fair to say, appetite for renewing the init-system discussion has been low. Now, though, the topic has returned to the fore and it would appear that the project is heading toward a new general resolution to decide at what level init systems other than systemd should be supported.

The Free Software Foundation's Respects Your Freedom program provides a certification for hardware that supports your freedom. A new website listing certified products has been launched. "In 2012, when we announced the first certification, we hosted information about the program and retailers as a simple page on the Free Software Foundation (FSF) Web site. With only one retailer selling one device, this was certainly satisfactory. As the program grew, we added each new device chronologically to that page, highlighting the newest certifications. We are now in a place where eight different retailers have gained nearly fifty certifications [...]. With so many devices available, across so many different device categories, it was getting more difficult for users to find what they were looking for in just a plain chronological list."

Stable kernels 5.3.10, 4.19.83, 4.14.153, 4.9.200, and 4.4.200 have been released. They all contain important fixes and users should upgrade.

Security updates have been issued by Debian (ampache, chromium, djvulibre, firefox-esr, gdal, and ruby-haml), Fedora (chromium, file, gd, hostapd, nspr, and rssh), openSUSE (bcm20702a1-firmware, firefox, gdal, libtomcrypt, php7, python-ecdsa, python3, samba, and thunderbird), SUSE (apache2-mod_auth_openidc, libssh2_org, and rsyslog), and Ubuntu (bash).

The seventh 5.4 prepatch is out for testing. "Nothing looks _bad_, but there is too much of it. So I'm leaning towards an rc8 being likely next weekend due to that, but I won't make a final decision yet. We'll see."

Operating systems and computing hardware both carry a lot of their history with them. The x86 I/O-port mechanism is one piece of that history; it is rarely used by hardware designed in the last 20 years, but it must still be supported. That doesn't mean that this support can't be cleaned up and improved, though, especially when the old implementation turns out to have some unpleasant properties. An example can be seen in the iopl() patch set from Thomas Gleixner.

The openSUSE project has been considering a name change as part of its move into a separate foundation since (at least) June. A long and somewhat controversial vote of project members has just come to an end, and the result is conclusive: 225-42 against the name change.

Security updates have been issued by Arch Linux (linux-hardened), Debian (fribidi), Gentoo (oniguruma, openssh/openssh, openssl, and pump), Mageia (chromium-browser-stable, expat, firefox, freetds, proftpd, python, thunderbird, and unbound), Oracle (sudo), Scientific Linux (thunderbird), Slackware (kernel), SUSE (rubygem-haml), and Ubuntu (fribidi and webkit2gtk).

As of this writing, just over 14,000 non-merge changesets have found their way into the mainline repository for the 5.4 release; that is a bit less than we saw for 5.3, but more than most of the other recent kernels. The final 5.4 release is approaching, so it must be time for our usual look at where the code merged in this development cycle came from. It's mostly business as usual in the kernel community, modulo an appearance from none other than Hulk Robot.

Security updates have been issued by Arch Linux (squid), Fedora (chromium, libssh2, and wpa_supplicant), openSUSE (chromium), Red Hat (ansible, chromium-browser, openstack-octavia, patch, qemu-kvm-rhev, sudo, and thunderbird), Scientific Linux (sudo), SUSE (bluez, gdb, php72, and thunderbird), and Ubuntu (cpio and rygel).

Version 1.39.0 of the Rust language is available. The biggest new feature appears to be the async/await mechanism, which is described in this blog post: "So, what is async await? Async-await is a way to write functions that can 'pause', return control to the runtime, and then pick up from where they left off. Typically those pauses are to wait for I/O, but there can be any number of uses."

The LWN.net Weekly Edition for November 7, 2019 is available.

Running untrusted code in a safe manner is generally the goal of sandboxing efforts. The sandbox technique presented by Georgia Tech PhD student Ashish Bijlani at Open Source Summit Europe 2019 is no exception. He has used something of a novel scheme to allow unprivileged code to implement the sandbox policies using BPF; the policies are then enforced by the kernel.

At Open Source Summit Europe 2019, Michael C. Jaeger and Maximilian Huber updated attendees on the FOSSology project, which is an open-source license-compliance tool. They introduced FOSSology and talked about how it can be used, but they also looked at the new features added in the last few releases. Beyond that, they presented some experiments the project has been doing with creating machine-learning models for license recognition.

Stable kernels 5.3.9, 4.19.82, 4.14.152, 4.9.199, and 4.4.199 have been released. They all contain important fixes and users should upgrade.

Security updates have been issued by Debian (cpio, openafs, proftpd-dfsg, simplesamlphp, and wordpress), Fedora (thunderbird), openSUSE (binutils, docker-runc, kernel, nfs-utils, php7, python3, and samba), Red Hat (389-ds:1.4, ansible, bind, container-tools:1.0, container-tools:rhel8, curl, dbus, dhcp, dovecot, edk2, elfutils, evolution, freeradius:3.0, gdb, gettext, glib2, glibc, GNOME, gnutls, go-toolset:rhel8, http-parser, httpd:2.4, kernel, kernel-rt, libarchive, libjpeg-turbo, libqb, libreswan, libseccomp, libtiff, libvorbis, lldpad, lua, mariadb:10.3, mod_auth_mellon, numpy, openssh, openssl, openstack-octavia, osinfo-db and libosinfo, php:7.2, php:7.3, python-urllib3, python27:2.7, python3, qemu-kvm-rhev, qt5-qtbase, rh-php70-php, rh-python36-python, samba, squid:4, sssd, sudo, systemd, virt-manager, virt:rhel, and yum), SUSE (ardana-ansible, ardana-horizon, ardana-keystone, ardana-manila, ardana-neutron, crowbar-core, crowbar-openstack, grafana, openstack-cinder, openstack-dashboard, openstack-horizon-plugin-manila-ui, openstack-keystone, openstack-manila, openstack-neutron, openstack-neutron-fwaas, openstack-neutron-lbaas, openstack-nova, openstack-octavia, openstack-octavia-amphora-image, pdns, python-Django1, python-keystonemiddleware, python-octaviaclient, python-os-brick, python-oslo.cache, python-oslo.messaging, gdb, and libssh2_org), and Ubuntu (firefox).

Linux systems have traditionally run with a single address space that is shared by user and kernel space. That changed with the advent of the Meltdown vulnerability, which forced the merging of kernel page-table isolation (KPTI) at the end of 2017. But, Mike Rapoport said during his 2019 Open Source Summit Europe talk, that may not be the end of the story for address-space isolation. There is a good case to be made for increasing the separation of address spaces, but implementing that may require some fundamental changes in how kernel memory management works.