Date: Fri, 6 Oct 2006 08:42:19 -0400 (EDT) From: Daniel Eischen <deischen@freebsd.org> To: Takahiro Kurosawa <takahiro.kurosawa@gmail.com> Cc: John Baldwin <john@baldwin.cx>, freebsd-gnats-submit@freebsd.org, freebsd-threads@freebsd.org Subject: Re: threads/103975: Implicit loading/unloading of libpthread.so may crash user processes Message-ID: <Pine.GSO.4.64.0610060841150.17773@sea.ntplx.net> In-Reply-To: <b72f377d0610060149id3d02dcxf5ccafe0e80fa18c@mail.gmail.com> References: <200610041356.k94DuOmj097237@www.freebsd.org> <200610050906.21304.john@baldwin.cx> <20061005194756.07580108@kan.dnsalias.net> <b72f377d0610060149id3d02dcxf5ccafe0e80fa18c@mail.gmail.com>
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On Fri, 6 Oct 2006, Takahiro Kurosawa wrote: > Alexander Kabaev <kabaev@gmail.com> wrote: >> On Thu, 5 Oct 2006 09:06:20 -0400 >> John Baldwin <john@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? : > LDFLAGS+=-Wl,-znodelete If that's the knob, then I'd agree. You also want to make the same change to libthr. -- Dan
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