linux-kernel - 5.x: userland writes to /usr/lib64/firefox/libxul.so

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Message-ID: <dfadf874-5fc7-6a0c-3193-7c3b907045ae@xs4all.nl>
Date:   Thu, 9 Apr 2020 15:22:08 +0200
From:   Udo van den Heuvel <udovdh@...all.nl>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: 5.x: userland writes to /usr/lib64/firefox/libxul.so

Hello,

In a bug at https://bugzilla.redhat.com/show_bug.cgi?id=1789477 we found
that firefox (running as a user) can somehow, sometimes write to
/usr/lib64/firefox/libxul.so when it (partly) crashes.
This may point to a situation that should not occur: the library in
question is owned by root and not writable by the user via conventional
methods.
Can anyone confirm this?
How can we approach to solving this issue?
Is this a possible kernel issue?
Or perhaps a linker issue?

Please explain...

Kind regards,
Udo