Segfault in _Unwind_* code called from pthread_exit

[Tijl Coosemans]

On Sun, 29 Oct 2017 20:40:46 +0100 Andreas Tobler <andreast-list at fgznet.ch> wrote:
> Attached what I have for libgcc. It can be applied to gcc5-8, should 
> give no issues. The mentioned tc from this thread and mine, 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82635 do pass.
> 
> What do you think?

Like I said before the return address can be anything.  It could for
instance point to some instruction in a random function and then the
stack unwinder will think thread_start was called from that function.
There's no check you can add to libgcc to distinguish that from a
normal valid return address.