bug#56108: 29.0.50; ASAN use-after-free in re_match_2_internal

[Eli Zaretskii]

> Date: Wed, 22 Jun 2022 16:10:23 +0200
> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: 56108@debbugs.gnu.org
> 
> Functions fast_string_match_internal* don't freeze in the sense you 
> explained.  What I don't see so far is
> what could lead to a GC in these cases, between the compile_pattern and the 
> use of its result...

I don't know if something inside re_match_2_internal can call
something that would trigger GC.  There's too much stuff going on
there, what with syntax tables and whatnot.

> Did you find other places where there's no freeze?

string_match_1, I think.