GNU bug report logs - #42931
27.1; json-pretty-print-buffer on ~2MB line causes core dump

Previous Next

Full log

Message #31 received at 42931-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 42931-done <at> debbugs.gnu.org, larsi <at> gnus.org, bruno <at> clisp.org,
 p.stephani2 <at> gmail.com, psainty <at> rcon.net.nz
Subject: Re: bug#42931: 27.1; json-pretty-print-buffer on ~2MB line causes
 core dump
Date: Tue, 25 Aug 2020 11:19:04 -0700

On 8/24/20 11:12 PM, Eli Zaretskii wrote:
> What about "normal" Emacs builds?  They usually have between 2MB and
> 8MB of stack.  Should we worry about stack overflow in these cases?

No. On x86-64 Ubuntu 18.04.5 each recursion level consumes 304 bytes. Dividing 2 
MB by 304 gives you 6578 stack frames, which means the algorithm could handle a 
vector of 2**6578 entries, which can't exist anywhere in the known physical 
universe.

On real machines it'd have to be reeeeally tiny stack for this recursion to be a 
significant problem now, so tiny that Emacs would crash for countless other 
reasons. I'll take the liberty of closing the bug report.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.