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+++ This bug was initially created as a clone of Bug #1672771 +++

There are 10 missing compiler barriers in pthread_mutex_trylock.c, which can under certain circumstances, allow an optimizing compiler to reorder stores such that the kernel can observe an inconsistent state in the robust list.

Stefan Liebler's (IBM) patch:
https://www.sourceware.org/ml/libc-alpha/2019-02/msg00129.html

My review:
https://www.sourceware.org/ml/libc-alpha/2019-02/msg00133.html

We should backport this to rhel-7.7, since in rhel-7.6 we did a lot of work to fix other robust mutex issues for the Samba team.

commit 823624bdc47f1f80109c9c52dee7939b9386d708
Author: Stefan Liebler <stli.com>
Date:   Thu Feb 7 15:18:36 2019 +0100

    Add compiler barriers around modifications of the robust mutex list for pthread_mutex_trylock. [BZ #24180]

Verified with objdump based on https://bugzilla.redhat.com/show_bug.cgi?id=1672771#c7 comment, also sanity check that patch was applied.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2019:3513