Fedora 34: FEDORA-2021-0cf36f9134 Critical: musl Buffer Overflow

musl is a C standard library to power a new generation

of Linux-based devices. It is lightweight, fast, simple,

free, and strives to be correct in the sense of standards

conformance and safety.

#### What's new for 1.2.2 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.

* Sun May 30 2021 Neal Gompa - 1.2.2-1

- Update to 1.2.2

[ 1 ] Bug #1900056 - CVE-2020-28928 musl: infinite loop in wcsnrtombs function [fedora-all]

https://bugzilla.redhat.com/show_bug.cgi?id=1900056

[ 2 ] Bug #1916568 - musl-1.2.2 is available

https://bugzilla.redhat.com/show_bug.cgi?id=1916568

su -c 'dnf upgrade --advisory FEDORA-2021-0cf36f9134' at the command

line. For more information, refer to the dnf documentation available at

https://dnf.readthedocs.io/en/latest/command_ref.html

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