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From: "carlos at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug dynamic-link/30062] glibc 2.36 loader has intermittent segfault
 error on ppc64le
Date: Tue, 31 Jan 2023 20:56:51 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D30062

Carlos O'Donell <carlos at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |carlos at redhat dot com
   Last reconfirmed|                            |2023-01-31
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Carlos O'Donell <carlos at redhat dot com> ---
(In reply to ChenQi from comment #0)
> Except the above backtrace and LD_DEBUG testing, I also done one more
> testing which made me believe the bug is in glibc.

The best bet here is to run with Valgrind and try to find the invalid acces=
s.

> I changed glibc to musl to check if it's the glibc's issue or not. The
> result is: when using musl, there's no segfault error. That's why I filed=
 a
> bug here.

Musl's dynamic loader will never unload a library and calling dlclose() does
not run the library desctructors.

glibc's dynamic loader will attempt to run destructors and unload and unmap=
 the
library.

Under glibc you must accurately account for any dangling references to the
library after unloading.

Thus I expect that this is related to the libraries you are loading and
unloading and their specific constructors and destructors.

I haven't seen any reports of this in Fedora 37, which uses glibc 2.36, and=
 has
syslog-ng compiled for ppc64le.

> related syslog-ng issue link:
> https://github.com/syslog-ng/syslog-ng/issues/4285

Thanks. I commented there.

Next steps:
- Please run your reproducer under valgrind and see if you can determine the
root cause of the crash.

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