threads/103975: Implicit loading/unloading of libpthread.so may
crash user processes
takahiro.kurosawa at gmail.com
Fri Oct 6 01:50:29 PDT 2006
The following reply was made to PR threads/103975; it has been noted by GNATS.
From: "Takahiro Kurosawa" <takahiro.kurosawa at gmail.com>
To: "Alexander Kabaev" <kabaev at gmail.com>
Cc: "John Baldwin" <john at baldwin.cx>, freebsd-threads at freebsd.org,
freebsd-gnats-submit at freebsd.org
Subject: Re: threads/103975: Implicit loading/unloading of libpthread.so may crash user processes
Date: Fri, 6 Oct 2006 17:49:48 +0900
Alexander Kabaev <kabaev at gmail.com> wrote:
> On Thu, 5 Oct 2006 09:06:20 -0400
> John Baldwin <john at baldwin.cx> wrote:
> > > To fix the problem, a function that has __attribute__((destructor))
> > > in libpthread should probably be implemented in order to recover
> > > the initial state before unloading.
> > I'm not sure you can recover the state actually, hence why I think
> > maybe we should make it so that libpthread doesn't unload once it has
> > been loaded.
I understand that it's way easier to prohibit unloading of libpthread
than to change the code safely unloadable.
Thanks for your explanation, John!
> Linux does not allow pthread library to be unloaded presumably because
> of reasons like this. From readelf -a /compat/linux/lib/libpthread.so.0:
> 0x6ffffffb (FLAGS_1) Flags: NODELETE INITFIRST
> Infortunately, rtld does not implement NODELETE and INITFIRST. Both are
> addressed in my patch that I am yet to commit.
I'm looking forward to the commit of your patch into the CVS repository :-)
Maybe the following line should be added to src/lib/libpthread/Makefile
when rtld supports the NODELETE flag? :
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