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Created attachment 1583048 [details]
Proposed fix

Description of problem:
libffi code searches for the tmpdir with exec to write and execute their temporal files from there. On hardened systems with most of the mounts mounted with noexec, it can fell through the explicit list of candidate dirs to the mtab search and then it can take the root directory ('/') which will result in SELinux AVCs. As most of the systems have /run mounted with exec, it could be worth adding it to the explicit list of candidates. Well, it will not solve the problem for everybody, because FHS doesn't say anything about exec/noexec of the /run, so customers could remount it noexec, but it would be definitely improvement. 

Version-Release number of selected component (if applicable):
libffi-3.0.13-18.el7.x86_64 

How reproducible:
Always

Steps to Reproduce:
1. check the code
2.
3.

Actual results:
/run is not in the explicit search list

Expected results:
/run could be in the explicit search list

Additional info:

I think the way forward here is to switch to a trampoline which does not need run-time code generation, only mapping of fixed, pre-compiled code.  Then all that dual-mapping and cache-flushing code can go away.

In RHEL7 we should just add the extra search directory and stop there, but in later releases we may have the opportunity to rework libffi.

As we have not gotten any feedback or solutions from upstream, we are unable to fix this bug in the RHEL 7 timeframe, as RHEL 7 is entering maintenance phase.  We will continue to track this request in RHEL 8.