Recent libX11 update broke emacs

[Niclas Zeising]

On 2020-08-03 19:07, Kevin Oberman wrote:
> This is a weird problem and I'm uncertain if it is in libW11, x11-server,
> or emacs. As a result, I'm crossposting to both lists.
> 
> Yesterday, after upgrading libX11 and x11-server, I could no longer run
> Emacs to an  X display. It crashed quickly with a segmentation error in the
> pthread library. Oddly, I could run it to my local xserver from a remote
> system.

Where does the segfault occur before entering pthreads?

> Rolling back the x11 server did not help nor did rolling back libX11 or
> even both of them. I had to roll back libX11 first and build the server
> with the old libX11. Rebuilding emacs with the new ports made no difference.

Which version of the server did you build?  The patch to xorg-server is 
trivial, just switching out malloc for calloc have the memory 0 
initialized.  The patch to libX11 is rather more involved.
It is possible that someone accidentally changed the ABI of libX11, I 
guess.  What happens if you use the version with just the security fixes 
(the version I committed first, and that was merged to the Q3 branch.)

> 
> Since the old libX11 contains a very serious vulnerability, I  really hate
> to leave it this way, but I also have a hard time getting anything done
> without emacs. Nothing other than emacs seems to have a problem with this

There is one commit after libX11 1.6.10, that takes care of a regression.
Can you apply
https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/93fce3f4e79cbc737d6468a4f68ba3de1b83953b 
on top of the libX11 1.6.10 update and see if that fixes anything?

Regards
-- 
Niclas