From: David Kastrup <dak@gnu.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: Paul Eggert <eggert@cs.ucla.edu>,
monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 8ba156f: Attempt to avoid crashes in plist-member
Date: Tue, 13 Oct 2015 17:08:52 +0200 [thread overview]
Message-ID: <87zizm7qm3.fsf@fencepost.gnu.org> (raw)
In-Reply-To: <83io6azufx.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 13 Oct 2015 17:58:42 +0300")
Eli Zaretskii <eliz@gnu.org> writes:
>> Cc: emacs-devel@gnu.org
>> From: Paul Eggert <eggert@cs.ucla.edu>
>> Date: Mon, 12 Oct 2015 20:36:06 -0700
>>
>> QUIT could call some Lisp.
>>
>> Sure, but Lisp cannot affect the value of CONSP (plist).
>
> Not the value of CONSP, the list itself. We follow the CONSP test
> with XCAR, which crashed. The only way I could imagine that happening
> is that the list got modified between the test and the XCAR call. Is
> there any other way to explain that?
Huh? CONSP only checks some bits on a pointer. It does not verify that
the pointer can be dereferenced into an existing cons cell. So there is
absolutely no need to modify anything between having a true CONSP test
and a crashing XCAR.
--
David Kastrup
next prev parent reply other threads:[~2015-10-13 15:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20151012170324.17966.77@vcs.savannah.gnu.org>
[not found] ` <E1ZlgVQ-0004gO-Em@vcs.savannah.gnu.org>
2015-10-13 1:07 ` [Emacs-diffs] master 8ba156f: Attempt to avoid crashes in plist-member Stefan Monnier
2015-10-13 2:42 ` Eli Zaretskii
2015-10-13 3:36 ` Paul Eggert
2015-10-13 14:58 ` Eli Zaretskii
2015-10-13 15:08 ` David Kastrup [this message]
2015-10-13 15:32 ` Eli Zaretskii
2015-10-13 15:50 ` David Kastrup
2015-10-13 15:21 ` Paul Eggert
2015-10-13 15:34 ` Eli Zaretskii
2015-10-13 19:05 ` Stefan Monnier
2015-10-13 8:00 ` Andreas Schwab
2015-10-13 15:01 ` Eli Zaretskii
2015-10-13 10:26 ` David Kastrup
2015-10-13 13:23 ` Stefan Monnier
2015-10-13 13:41 ` David Kastrup
2015-10-13 15:16 ` Eli Zaretskii
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