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Bug 1664408

Summary: glibc: Only build libm with -fno-math-errno
Product: Red Hat Enterprise Linux 8 Reporter: Florian Weimer <fweimer>
Component: glibcAssignee: Florian Weimer <fweimer>
Status: CLOSED ERRATA QA Contact: qe-baseos-tools-bugs
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 8.1CC: ashankar, codonell, dj, fweimer, mcermak, mnewsome, pfrankli, skolosov
Target Milestone: rcKeywords: Patch
Target Release: 8.1Flags: pm-rhel: mirror+
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: glibc-2.28-46.el8 Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-11-05 21:29:04 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1682593    
Bug Blocks: 1684553, 1701002    
Deadline: 2019-04-24   

Description Florian Weimer 2019-01-08 17:14:41 UTC
glibc is currently built with -fno-math-errno.  This GCC option affects more than math functions, so it leads to build (strerror resetting errno when formatting an unknown error number is one known instance).

We should backport this upstream commit:

commit 2ef427168818ce04b03cecb7b739f9db0156e3e4
Author: Aurelien Jarno <aurelien>
Date:   Thu Jan 3 15:51:37 2019 +0100

    Only build libm with -fno-math-errno (bug 24024)
    
    Commit 1294b1892e ("Add support for sqrt asm redirects") added the
    -fno-math-errno flag to build most of the glibc in order to enable GCC
    to inline math functions. Due to GCC bug #88576, saving and restoring
    errno around calls to malloc are optimized-out. In turn this causes
    strerror to set errno to ENOMEM if it get passed an invalid error number
    and if malloc sets errno to ENOMEM (which might happen even if it
    succeeds). This is not allowed by POSIX.
    
    This patch changes the build flags, building only libm with
    -fno-math-errno and all the remaining code with -fno-math-errno. This
    should be safe as libm doesn't contain any code saving and restoring
    errno around malloc. This patch can probably be reverted once the GCC
    bug is fixed and available in stable releases.

Comment 3 Sergey Kolosov 2019-08-16 14:17:28 UTC
Verified with ./string/test-strerror-errno glibc test

Comment 5 errata-xmlrpc 2019-11-05 21:29:04 UTC
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