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Bug 1664408 - glibc: Only build libm with -fno-math-errno
Summary: glibc: Only build libm with -fno-math-errno
Keywords:
Status: CLOSED ERRATA
Alias: None
Deadline: 2019-04-24
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: glibc
Version: 8.1
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: 8.1
Assignee: Florian Weimer
QA Contact: qe-baseos-tools-bugs
URL:
Whiteboard:
Depends On: 1682593
Blocks: 1684553 1701002
TreeView+ depends on / blocked
 
Reported: 2019-01-08 17:14 UTC by Florian Weimer
Modified: 2023-07-18 14:30 UTC (History)
8 users (show)

Fixed In Version: glibc-2.28-46.el8
Doc Type: No Doc Update
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-11-05 21:29:04 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
GNU Compiler Collection 88576 0 None None None 2019-07-11 07:18:18 UTC
Red Hat Product Errata RHSA-2019:3513 0 None None None 2019-11-05 21:29:24 UTC
Sourceware 24024 0 None None None 2019-07-11 07:18:18 UTC

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
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