This release features the new "mallocng" malloc implementation, replacing musl's original dlmalloc-like allocator that suffered from fundamental design problems. Its major user-facing new properties are the ability to return freed memory on a much finer granularity and avoidance of many catastrophic fragmentation patterns. In addition it provides strong hardening against memory usage errors by the caller, including detection of overflows, double-free, and use-after-free, and does not admit corruption of allocator state via these errors.
Other enhancements in this release include changes to the
res_* API to report DNSSEC status of the results (needed for correct implementation of DANE in applications) and new arch-specific optimized string and math functions, especially
memset for AAarch64.
A major logic/synchronization error in lock skipping after a multi-threaded process returns to single-threaded state has been fixed, along with a number of lesser bugs, including some time64-related regressions on 32-bit archs. One of these was actually a kernel vdso bug that broke
clock_gettime on arm on hardware where the vdso should not be used; as a result, arm vdso support has been disabled until there is a reliable and inexpensive way to detect whether it's safe to use. Bugs and recent regressions affecting all mips archs and other arch-specific bugs have also been fixed.
sudo dnf upgrade --refresh --advisory=FEDORA-2020-9f026ae79e
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