From: Philipp Stephani <p.stephani2@gmail.com>
To: 27258@debbugs.gnu.org
Subject: bug#27258: 26.0.50; Possible undefined behavior in Fmapbacktrace
Date: Mon, 05 Jun 2017 20:13:37 +0000 [thread overview]
Message-ID: <CAArVCkQ86TupKsQzDneQUd9oh+BEDe3eUh3NLQ4=O_+t2g4REQ@mail.gmail.com> (raw)
In-Reply-To: <m21sqymcvj.fsf@p>
[-- Attachment #1: Type: text/plain, Size: 1002 bytes --]
Philipp <p.stephani2@gmail.com> schrieb am Mo., 5. Juni 2017 um 21:51 Uhr:
>
> Insert the following into /tmp/rec.el:
>
> ;; -*- lexical-binding: t; -*-
>
> (require 'cl-lib)
>
> (defun recurse (i g)
> (if (= i 0)
> (funcall g (cl-gensym))
> (recurse (1- i) g)))
>
> (recurse 100 (lambda (sym)
> (message "outer: %s" sym)
> (mapbacktrace
> (lambda (_ _ args _)
> (recurse 100 (lambda (sym)
> (message "inner: %s %s" sym args)))))))
>
> Then run
>
> emacs -Q -batch -l /tmp/rec.el
>
> The printed messages will either be way too short, or Emacs will
> segfault. Re-running the command a couple of times consistently
> generated a segfault for me.
>
> My guess is that pdlvec got reallocated, but Fmapbacktrace uses pointers
> instead of indices to access its element, so they pointers became
> invalidated and point to garbage.
Fixed with commit 3d9d976aa476b1c1098359a1215ad1cabd022d33.
[-- Attachment #2: Type: text/html, Size: 1464 bytes --]
next prev parent reply other threads:[~2017-06-05 20:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-05 19:51 bug#27258: 26.0.50; Possible undefined behavior in Fmapbacktrace Philipp
2017-06-05 20:13 ` Philipp Stephani [this message]
2017-06-05 20:14 ` Philipp Stephani
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAArVCkQ86TupKsQzDneQUd9oh+BEDe3eUh3NLQ4=O_+t2g4REQ@mail.gmail.com' \
--to=p.stephani2@gmail.com \
--cc=27258@debbugs.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).