From: Eli Zaretskii <eliz@gnu.org>
To: npostavs@users.sourceforge.net
Cc: 24751@debbugs.gnu.org
Subject: bug#24751: 26.0.50; Regex stack overflow not detected properly (gets "Variable binding depth exceeds max-specpdl-size")
Date: Tue, 15 Nov 2016 18:12:09 +0200 [thread overview]
Message-ID: <83d1hwhgdi.fsf@gnu.org> (raw)
In-Reply-To: <87wpg5l9st.fsf@users.sourceforge.net> (npostavs@users.sourceforge.net)
> From: npostavs@users.sourceforge.net
> Cc: 24751@debbugs.gnu.org
> Date: Mon, 14 Nov 2016 22:08:18 -0500
>
> Actually, we should avoid increasing this limit if the stack wasn't
> increased, right? Here's what I came up with, I think it doesn't cover
> Cygwin/Windows though.
>
> diff --git c/src/emacs.c i/src/emacs.c
> index b74df21..d4655c8 100644
> --- c/src/emacs.c
> +++ i/src/emacs.c
> @@ -831,8 +831,8 @@ main (int argc, char **argv)
> re_max_failures, then add 33% to cover the size of the
> smaller stacks that regex.c successively allocates and
> discards on its way to the maximum. */
> - int ratio = 20 * sizeof (char *);
> - ratio += ratio / 3;
> + int min_ratio = 20 * sizeof (char *);
> + int ratio = min_ratio + min_ratio / 3;
>
> /* Extra space to cover what we're likely to use for other reasons. */
> int extra = 200000;
> @@ -869,6 +869,7 @@ main (int argc, char **argv)
>
> /* Don't let regex.c overflow the stack. */
> re_max_failures = lim < extra ? 0 : min (lim - extra, SIZE_MAX) / ratio;
> + emacs_re_safe_alloca = re_max_failures * min_ratio;
> }
> #endif /* HAVE_SETRLIMIT and RLIMIT_STACK and not CYGWIN */
Right, but I have 2 comments:
. we shouldn't set re_max_failures to zero if the amount of stack is
less than 'extra', since in that case we will allocate the failure
stack off the heap;
. emacs_re_safe_alloca should have its minimum value MAX_ALLOCA, not
zero, because SAFE_ALLOCA can still be used in regex.c, even
though the failure stack will be malloc'ed.
Thanks.
next prev parent reply other threads:[~2016-11-15 16:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-21 3:54 bug#24751: 26.0.50; Regex stack overflow not detected properly (gets "Variable binding depth exceeds max-specpdl-size") npostavs
2016-11-04 8:22 ` Eli Zaretskii
2016-11-05 19:34 ` npostavs
2016-11-06 15:45 ` Eli Zaretskii
2016-11-13 5:39 ` npostavs
2016-11-13 16:12 ` Eli Zaretskii
2016-11-15 3:08 ` npostavs
2016-11-15 16:12 ` Eli Zaretskii [this message]
2016-11-16 1:06 ` npostavs
2016-11-16 16:25 ` Eli Zaretskii
2016-11-16 23:25 ` npostavs
2016-11-17 16:21 ` Eli Zaretskii
2016-11-19 10:02 ` Eli Zaretskii
2017-01-01 18:33 ` npostavs
2017-01-01 18:41 ` Eli Zaretskii
2017-01-01 18:57 ` npostavs
2017-01-01 20:06 ` Eli Zaretskii
2017-01-02 4:49 ` npostavs
2017-01-02 15:24 ` Eli Zaretskii
2017-01-02 18:30 ` npostavs
2017-01-02 19:22 ` Eli Zaretskii
2017-01-08 23:49 ` npostavs
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