From: Philipp Stephani <p.stephani2@gmail.com>
To: 27258-done@debbugs.gnu.org
Subject: bug#27258: 26.0.50; Possible undefined behavior in Fmapbacktrace
Date: Mon, 05 Jun 2017 20:14:32 +0000 [thread overview]
Message-ID: <CAArVCkSLE0KFoj7tgTyHvAetkrzciwPrx-8D79pqwGh=sb9ugQ@mail.gmail.com> (raw)
In-Reply-To: <CAArVCkQ86TupKsQzDneQUd9oh+BEDe3eUh3NLQ4=O_+t2g4REQ@mail.gmail.com>
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Philipp Stephani <p.stephani2@gmail.com> schrieb am Mo., 5. Juni 2017 um
22:13 Uhr:
> 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.
>
Woops, sent to wrong email address.
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prev parent reply other threads:[~2017-06-05 20:14 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
2017-06-05 20:14 ` Philipp Stephani [this message]
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