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List:       apache-httpd-dev
Subject:    Re: process_regexp bug, infinite recursion
From:       Yann Ylavic <ylavic.dev () gmail ! com>
Date:       2024-01-16 17:45:45
Message-ID: CAKQ1sVN1M0XJ_Rh7Ye3Rd2qbkV3AB8ED+EgyKmk3KJjdPBi5XA () mail ! gmail ! com
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On Mon, Jan 8, 2024 at 5:54 PM Ruediger Pluem <rpluem@apache.org> wrote:
>
> On 1/8/24 1:37 PM, Yann Ylavic wrote:
> >
> > As noted in v2 we have an issue here by "losing" the beginning of the
> > value on recursion:
> >             /* XXX: recursing by using AP_REG_NOTBOL (because we are not at ^
> >              * anymore) and then "losing" the beginning of the string is not
> >              * always correct. Say we match "(?<=a)ba" against "ababa", on
> >              * recursion ap_regexec_len() will not know that the second "b" is
> >              * preceded by "a" thus not match. We'd need a new ap_regexec_ex()
> >              * that can take match_end as an offset to fix this..
> >              */
> >
> > Not sure how far we should go with this patch..
>
> I think things do not get worse in this respect because of this patch but only improve
> in the sense that an infinite recursion is avoided.
> Hence +1 on the patch.

I finally went with the full thing in r1915267, r1915268 and r1915271
(with new tests in r1915269 for what didn't work well).


Regards;
Yann.
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