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: Sun, 06 Nov 2016 17:45:40 +0200 [thread overview]
Message-ID: <83zilcipcr.fsf@gnu.org> (raw)
In-Reply-To: <87mvhdoh4q.fsf@users.sourceforge.net> (npostavs@users.sourceforge.net)
> From: npostavs@users.sourceforge.net
> Cc: 24751@debbugs.gnu.org
> Date: Sat, 05 Nov 2016 15:34:29 -0400
>
> >> #define TYPICAL_FAILURE_SIZE 20
> >>
> >> Why do we use an "estimate" here? What's wrong with just using
> >> (re_max_failures * sizeof (fail_stack_elt_t)) as the limit? Or should
> >> the limit actually be (re_max_failures * TYPICAL_FAILURE_SIZE * sizeof
> >> (fail_stack_elt_t))?
> >
> > I think it should be the latter, indeed.
> >
> > Can you propose a patch along those lines that would remove the
> > infloop in ENSURE_FAIL_STACK?
> >
> > Thanks.
>
> The below seems to work
Thanks.
I think the patch can be simplified, where we now multiply by the size
of fail_stack_elt_t and then divide by it: simply remove both the
multiplication and the division. That will make the code easier to
read, and will make the units of each variable clear, something that I
think is at the heart of this issue.
> but effectively increases the size of the failure stack (so the
> sample file size has to be increased 8-fold to get a regex stack
> overflow).
Which IMO is exactly TRT, since re_max_failures was computed given the
runtime stack size of 8MB, so having it bail out after merely 800KB
doesn't sound right to me, don't you agree?
> Strangely, changing the value in the definition of re_max_failures
> doesn't seem to have any effect, it stays 40000 regardless. I am
> quite confused.
I don't think I follow. Can you tell what you tried to change, and
where did you see the lack of any effect?
next prev parent reply other threads:[~2016-11-06 15:45 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 [this message]
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
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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