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Gentoo Linux Security Advisory                           GLSA 202409-22
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: GCC: Flawed Code Generation
     Date: September 24, 2024
     Bugs: #719466
       ID: 202409-22

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Synopsis
========

A vulnerability has been discovered in GCC, which can lead to flawed
code generation.

Background
==========

The GNU Compiler Collection includes front ends for C, C++, Objective-C,
Fortran, Ada, Go, D and Modula-2 as well as libraries for these
languages (libstdc++,...).

Affected packages
=================

Package        Vulnerable    Unaffected
-------------  ------------  ------------
sys-devel/gcc  < 10.0        >= 10.0

Description
===========

A vulnerability has been discovered in GCC. Please review the CVE
identifier referenced below for details.

Impact
======

The POWER9 backend in GNU Compiler Collection (GCC) could optimize
multiple calls of the __builtin_darn intrinsic into a single call, thus
reducing the entropy of the random number generator. This occurred
because a volatile operation was not specified. For example, within a
single execution of a program, the output of every __builtin_darn() call
may be the same.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All GCC users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=sys-devel/gcc-10.0"

And then select it with gcc-config:

  # gcc-config latest

In this case, users should also rebuild all affected packages with
emerge -e, e.g.:

  # emerge --usepkg=n --emptytree @world

References
==========

[ 1 ] CVE-2019-15847
      https://nvd.nist.gov/vuln/detail/CVE-2019-15847

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

 https://security.gentoo.org/glsa/202409-22

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users' machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======

Copyright 2024 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

https://creativecommons.org/licenses/by-sa/2.5