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>
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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.
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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
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