bug#30626: 26.0.91; Crash when traversing a `stream-of-directory-files'

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@gmail.com>
> Cc: michael_heerdegen@web.de,  john.b.mastro@gmail.com,  nicolas@petton.fr,  
> 30626@debbugs.gnu.org
> Date: Mon, 12 Mar 2018 21:59:57 -0400
> 
> 4985        mark_maybe_pointer (*(void **) pp);
> (gdb) p pp
> $28 = 0x7fffffffa968 "\220L\346\002"

Should you look at pp or at *pp?

Also note that for Lisp objects that are marked you need to reset
their mark bit before trying to determine their type and value.

If none of the above helps, please walk me through the steps that led
you to look at -0x268(%rbp), because I'm not sure I follow.