The 5.3 kernel is out
The 5.3 kernel is available at last. The announcement
includes a long discussion about user-space regressions — an ext4 filesystem
performance improvement had caused some systems to fail booting due to a lack of
entropy early after startup. "It's more that it's an instructive example of
what counts as a regression, and what the whole 'no regressions' kernel rule
means. The reverted commit didn't change any API's, and it didn't introduce any
new bugs. But it ended up exposing another problem, and as such caused a kernel
upgrade to fail for a user. So it got reverted." Some of the more significant
changes in 5.3 include scheduler utilization clamping, the pidfd_open() and
clone3() system calls, bounded loop support for BPF programs, support for the
0.0.0.0/8 IPv4 address range, a new configuration option for the soon-to-be-
merged realtime preemption code, and more. See the KernelNewbies 5.3 page for
lots of details.
[$] Dealing with automated kernel bug reports
There is value in automatic testing systems, but they also
present a problem of their own: how can one keep up with the high volume of bug
reports that they generate? At the 2019 Linux Kernel Maintainers Summit, Shuah
Khan ran a session dedicated to this issue. There was general agreement that
the reports are hard to deal with, but not a lot of progress toward a
solution.
[$] Defragmenting the kernel development process
The first session at the 2019 Linux Kernel Maintainers
Summit was a last-minute addition to the schedule. Dmitry Vyukov's Linux
Plumbers Conference session on the kernel development process (slides [PDF]) had
inspired a number of discussions that, it was agreed, should carry over into the
summit. The result was a wide-ranging conversation about the kernel's
development tools and what could be done to improve them.
Security updates for Friday
Security updates have been issued by Debian (curl, dnsmasq,
and golang-go.crypto), Mageia (docker, firefox, flash-player-plugin,
ghostscript, links, squid, sympa, tcpflow, thunderbird, and znc), openSUSE
(srt), Oracle (.NET Core, kernel, libwmf, and poppler), Scientific Linux
(firefox), SUSE (cri-o, curl, java-1_8_0-ibm, python-SQLAlchemy, and python-
urllib3), and Ubuntu (curl and expat).
[$] Comparing GCC and Clang security features
Hardening must be performed at all levels of a system,
including in the compiler that is used to build that system. There are two
viable compilers in the free-software community now, each of which offers a
different set of security features. Kees Cook ran a session during the
Toolchains microconference at the 2019 Linux Plumbers Conference that examined
the security-feature support provided by both GCC and LLVM Clang, noting the
places where each one could stand to improve.
