bug#58334: 29.0.50; ASAN heap use after free in gui_produce_glyphs

[Po Lu]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Redisplay has two phases:
>
> 1. Building desired matrices, that is, what should be on the screen
> after redisplay.

Well, at least there's this in redisplay_internal (I think you wrote
it):

  /* I don't think this happens but let's be paranoid.  */
  if (redisplaying_p) <=================================
    return;

So perhaps the right thing to do would be to replace the comment with
one saying that process_pending_signals can potentially cause redisplay
to be called within itself.