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XFS filesystem maintainer Darrick Wong summarizes the significant XFS developments from the last year. "The year 2038 poses a special problem for Linux -- any signed 32-bit seconds counter will overflow back to 1901. Work is underway in the kernel to extend all of those counters to support 64-bit counters fully. In 2020, we will begin work on extending XFS's metadata (primarily inode timestamps and quota expiration timer) to support timestamps out to the year 2486. It should be possible to upgrade to existing V5 filesystems."

Stable kernels 5.4.3, 5.3.16, and 4.19.89 have been released. They all contain important fixes throughout the tree and users should upgrade.

Security updates have been issued by Debian (davical, intel-microcode, libpgf, php-horde, spamassassin, spip, and thunderbird), Mageia (clementine, dnsmasq, git, jasper, kdelibs4, kernel, libcroco, libgit2, libvirt, ncurses, openafs, proftpd, qbittorrent, signing-party, squid, and wireshark), openSUSE (java-1_8_0-openjdk and postgresql), Oracle (kernel), Red Hat (chromium-browser and openslp), and SUSE (kernel, libssh, and xen).

The second 5.5 kernel prepatch is out. "Things look normal - rc2 is usually fairly calm, and so it was this week too."

ZDNet reports on a police raid at the NGINX office. "Moscow police executed the raid after last week the Rambler Group filed a copyright violation against NGINX Inc., claiming full ownership of the NGINX web server code. The Rambler Group is the parent company of rambler.ru, one of Russia's biggest search engines and internet portals. According to copies of the search warrant posted on Twitter today, Rambler claims that Igor Sysoev developed NGINX while he was working as a system administrator for the company, hence they are the rightful owner of the project."

The saga of get_user_pages() — and the problems it causes within the kernel — has been extensively chronicled here; see the LWN kernel index for the full series. In short, get_user_pages() is used to pin user-space pages in memory for some sort of manipulation outside of the owning process(es); that manipulation can sometimes surprise other parts of the kernel that think they have exclusive rights to the pages in question. This patch series from John Hubbard does not solve all of the problems, but it does create some infrastructure that may make a solution easier to come by.

Security updates have been issued by Fedora (knot-resolver and xen), openSUSE (kernel), and SUSE (haproxy, kernel, and openssl).

Linux offers two modes for file I/O: buffered and direct. Buffered I/O passes through the kernel's page cache; it is relatively easy to use and can yield significant performance benefits for data that is accessed multiple times. Direct I/O, instead, goes straight between a user-space buffer and the storage device. It can be much faster for situations where caching by the operating system isn't necessary, but it is complex to use and contains traps for the unwary. Now, it seems, Jens Axboe has come up with a way to get many of the benefits of direct I/O with a lot less bother.

Security updates have been issued by CentOS (firefox and nss-softokn), Fedora (samba), Oracle (nss, nss-softokn, nss-util, nss-softokn, and thunderbird), Scientific Linux (thunderbird), SUSE (firefox), and Ubuntu (librabbitmq and samba).

The LWN.net Weekly Edition for December 12, 2019 is available.

An effort to protect package downloads from the Python Package Index (PyPI) has resulted in a Python Enhancement Proposal (PEP) and, perhaps belatedly, some discussion in the wider community. The basic idea is to use The Update Framework (TUF) to protect PyPI users from some malicious actors who are aiming to interfere with the installation and update of Python modules. But the name of the PEP and its wording, coupled with some recent typosquatting problems on PyPI, caused some confusion along the way. There are some competing interests and different cultures coming together over this PEP; the process has not run as smoothly as anyone might want, though that seems to be resolving itself at this point.

Security updates have been issued by Arch Linux (crypto++ and thunderbird), Debian (cacti, freeimage, git, and jackson-databind), Fedora (nss), openSUSE (clamav, dnsmasq, munge, opencv, permissions, and shadowsocks-libev), Red Hat (nss, nss-softokn, nss-util, rh-maven35-jackson-databind, and thunderbird), Scientific Linux (nss, nss-softokn, nss-util, nss-softokn, and thunderbird), SUSE (caasp-openstack-heat-templates, crowbar-core, crowbar-openstack, crowbar-ui, etcd, flannel, galera-3, mariadb, mariadb-connector-c, openstack-dashboard-theme-SUSE, openstack-heat-templates, openstack-neutron, openstack-nova, openstack-quickstart, patterns-cloud, python-oslo.messaging, python-oslo.utils, python-pysaml2, libssh, and strongswan), and Ubuntu (git, libpcap, libssh, and thunderbird).

The Electronic Frontier Foundation has posted a detailed study on third-party corporate surveillance on the Internet (and beyond). "Both Google and Apple encourage developers to use ad IDs for behavioral profiling in lieu of other identifiers like IMEI or phone number. Ostensibly, this gives users more control over how they are tracked, since users can reset their identifiers by hand if they choose. However, in practice, even if a user goes to the trouble to reset their ad ID, it’s very easy for trackers to identify them across resets by using other identifiers, like IP address or in-app storage. Android’s developer policy instructs trackers not to engage in such behavior, but the platform has no technical safeguards to stop it. In February 2019, a study found that over 18,000 apps on the Play store were violating Google’s policy."

A new mechanism to help thwart return-oriented programming (ROP) and similar attacks has recently been added to the OpenBSD kernel. It will block system calls that are not made via the C library (libc) system-call wrappers. Instead of being able to string together some "gadgets" that make a system call directly, an attacker would need to be able to call the wrapper, which is normally at a randomized location.

The Kubernetes scheduler is being overhauled with a series of improvements that will introduce a new framework and enhanced capabilities that could help cluster administrators to optimize performance and utilization. Abdullah Gharaibeh, co-chair of the Kubernetes scheduling special interest group (SIG Scheduling), detailed what has been happening with the scheduler in recent releases and what's on the roadmap in a session at KubeCon + CloudNativeCon North America 2019.

The Git project has released Git v2.24.1, v2.23.1, v2.22.2, v2.21.1, v2.20.2, v2.19.3, v2.18.2, v2.17.3, v2.16.6, v2.15.4, and v2.14.6. "These releases fix various security flaws, which allowed an attacker to overwrite arbitrary paths, remotely execute code, and/or overwrite files in the .git/ directory etc." The release notes contained in this announcement have the details.

Google Open Source has announced Google Summer of Code (GSoC) 2020, a program that introduces university students to open source development. "And the 'special sauce' that has kept this program thriving for 16 years: the mentorship aspect of the program. Participants gain invaluable experience working directly with mentors who are dedicated members of these open source communities; mentors help bring students into their communities while teaching them, guiding them and helping them find their place in the world of open source." Applications for interested organizations open on January 14.

Security updates have been issued by Debian (firefox-esr, jruby, and squid3), Fedora (librabbitmq, libuv, and xpdf), openSUSE (calamares and opera), Oracle (kernel and nss), Red Hat (httpd24-httpd, kernel, kernel-alt, kpatch-patch, nss-softokn, sudo, and thunderbird), SUSE (apache2-mod_perl, java-1_8_0-openjdk, and postgresql), and Ubuntu (eglibc, firefox, and samba).

Daniel Vetter has posted a summary of his LPC talk on kernel graphics drivers. "Unfortunately the business case for 'upstream first' on the kernel side is completely broken. Not for open source, and not for any fundamental reasons, but simply because the kernel moves too slowly, is too big, drivers aren’t well contained enough and therefore customer will not or even can not upgrade. For some hardware upstreaming early enough is possible, but graphics simply moves too fast: By the time the upstreamed driver is actually in shipping distros, it’s already one hardware generation behind. And missing almost a year of tuning and performance improvements. Worse it’s not just new hardware, but also GL and Vulkan versions that won’t work on older kernels due to missing features, fragmenting the ecosystem further."

By the end of the merge window, 12,632 non-merge changesets had been pulled into the mainline repository for the 5.5 release. This is thus a busy development cycle — just like the cycles that preceded it. Just over half of those changesets were pulled after the writing of our first 5.5 merge-window summary. As is often the case later in the merge window, many of those changes were relatively boring fixes. There were still a number of interesting changes, though; read on for a summary of what happened in the second half of this merge window.