bug#24911: 25.1; Emacs hangs or crashes on use of read syntax for circular objects in IELM

[Eli Zaretskii]

forcemerge 24640 24911
thanks

> From: Gemini Lasswell <gazally@runbox.com>
> Cc: 
> Date: Thu, 10 Nov 2016 11:25:52 -0800
> 
> I have just made it happen under gdb, with a breakpoint on
> handle_sigsegv. Here is the output of 'bt full'. It tells me
> 'xbacktrace' is an undefined command. This is my first time working with
> gdb.
> 
> (gdb) bt full
> #0  0x000000010023ca45 in mark_object (arg=...) at alloc.c:6501
>         obj = {i = 4287568137794125953}
>         po = 0x3b8080813b808080
>         cdr_count = 0
> #1  0x000000010023cca1 in mark_object (arg=...) at alloc.c:6552
>         ptr = 0x7fff5fbf8288
>         obj = {i = 140734799774347}
>         po = 0x7fff5fbf8288
>         cdr_count = 1
> #2  0x000000010023b8fb in garbage_collect_1 (end=0x7fff5fbf69a8) at 
> alloc.c:5760
>         nextb = 0x0
>         stack_top_variable = 0 '\000'
>         i = 201
          ^^^^^^^
This is bug#24640, already fixed on the emacs-25 branch.