bug#26932: Found the triggering behaviour

[Lars Ingebrigtsen <larsi@gnus.org>]

Vivek Dasmohapatra <vivek@etla.org> writes:

>> If I understand correctly, the external lui package set buffer-undo-list
>> to something invalid, and this led Emacs to segfault when gc-ing?
>
> Not invalid as such - entries were removed from the list while it was
> "in flight" through a mapc/mapcar and a double free (or similar)
> occurred.
>
>> Was there any further work done here, or a reproducible test case
>> written?
>
> No test case was written, the code for lui was changed to operate on
> a copy of the undo list, then assign that back to the original head
> variable instead.

You can make the Emacs gc segfault pretty trivially by making lists that
are recursive in just the wrong way, but it'd be interesting to see just
what it was that lui.el was doing.  But if there's no test case, then it
seem unlikely that we'll make further progress on this bug report.

So I'm closing this bug report.  If further progress can be made, please
either open a new bug report or respond to this and it'll be reopened.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no