The release adds the _Fork function from the upcoming edition of POSIX and takes advantage of the interpretation dropping the async-signal-safety requirement from fork to provide a consistent execution environment (not restricted to calling only async-signal-safe functions) after a multithreaded parent forks. This solves deadlocks which would otherwise be effectively unfixable in some language runtimes that expose fork as part of their contract with applications, as well as various library and application software that could and should be fixed, but hasn't been. A number of related issues in synchronization between fork, abort, async IO, posix_spawn, pthread_exit, and other components have been fixed as part of this change.
The realpath function has been rewritten to do its own path traversal, rather than depending on procfs magic symlink contents for O_PATH file descriptors. This makes it work prior to mount of /proc and in container or chroot environments where /proc contents may not accurately reflect the pathname as visible to the calling process.
The C versions of the square root functions, used on archs without a native FPU instruction for square root, have also been rewritten with significant improvements to performance, especially on archs that lack FPU entirely. This rewrite also fixes the lack of accurate sqrtl on archs with quad-precision long double.
New functions added include the aforementioned _Fork, reallocarray from OpenBSD, gettid along with SIGEV_THREAD_ID timer notification support, and tcgetwinsize/tcsetwinsize from POSIX-future.
A buffer overflow (CVE-2020-28928) in wcsnrtombs has been fixed with the function essentially rewritten. This function is not widely used and the bug is not relevant to software that does not use it directly (it's not used by other libc components), but it may be serious for software that does. An assortment of lesser bugs have also been fixed.
Updates may require up to 24 hours to propagate to mirrors. If the following command doesn't work, please retry later:
sudo dnf upgrade --refresh --advisory=FEDORA-2021-0cf36f9134Please login to add feedback.
This update has been submitted for testing by ngompa.
This update's test gating status has been changed to 'ignored'.
This update's test gating status has been changed to 'waiting'.
ngompa edited this update.
This update's test gating status has been changed to 'ignored'.
This update has been pushed to testing.
This update has been submitted for stable by bodhi.
This update has been pushed to stable.