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Re: alloca()-support

Message-ID <chs96g-nm41.ln1@wilbur.25thandClement.com> (permalink)
From William Ahern <william@25thandClement.com>
Subject Re: alloca()-support
Newsgroups comp.lang.c++, comp.lang.c
References <qmsqs0$472$1@news.albasani.net> <qmt93c$4sg$1@news.albasani.net>
Date 2019-09-30 11:01 -0700

Cross-posted to 2 groups.

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Bonita Montero <Bonita.Montero@gmail.com> wrote:
> I just came across another issue:
> With my primary compiler theres's an internal function called __chkstk
> called when I do alloca. This function is usually called when there are
> more than a page full of variables in the stack-frame. That's because
> Windows recognizes the need for more stack space only through touching
> the next unmapepd page down the stack. So why hasn't MS so be so clever
> as to design Windows that it would also recoginize noncontignous acces-
> ses to the stack-pages? Are these pages handled are like being over-
> comitted?

The compiler does this to ensure the alloca'd region doesn't extend past the
stack guard page. The kernel can handle noncontiguous stack access, but what
happens if your block extends *past* the stack into the dynamic heap region?

See https://blog.qualys.com/securitylabs/2017/06/19/the-stack-clash
and https://lwn.net/Articles/725832/ for more info

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Thread

alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 14:02 +0200
  Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-09-30 07:02 -0700
    Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:09 +0200
      Re: alloca()-support Bo Persson <bo@bo-persson.se> - 2019-09-30 17:29 +0200
        Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 17:33 +0200
    Re: alloca()-support gazelle@shell.xmission.com (Kenny McCormack) - 2019-09-30 16:26 +0000
  Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:12 +0300
    Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:16 +0200
      Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:30 +0300
        Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:44 +0200
          Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 00:36 +0300
            Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:28 +0200
              Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 16:08 +0300
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 15:42 +0200
    Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 14:30 +0000
      Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:33 +0300
        Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-09-30 16:56 +0200
    Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-09-30 15:29 +0000
      Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 17:31 +0200
        Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 07:03 +0000
          Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 10:57 +0200
            Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 18:49 +0000
              Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:20 +0200
                Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 20:39 +0000
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:15 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:28 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:29 +0000
    Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-09-30 11:14 -0700
  Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:04 +0200
    Re: alloca()-support William Ahern <william@25thandClement.com> - 2019-09-30 11:01 -0700
      Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:19 +0200
    Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-09-30 22:26 +0300
      Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 19:46 +0000
    Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:32 +0200
      Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-10-01 09:08 +0300
        Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 08:35 +0200
  Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 18:48 +0200
    Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:51 +0200
      Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 18:55 +0200
        Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:58 +0200
          Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 19:53 +0200
            Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-09-30 11:13 -0700
            Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 19:38 +0000
              Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:41 +0200
                Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 15:19 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 17:31 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 18:58 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:24 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:28 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:30 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:36 +0000
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:01 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:42 +0000
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:10 +0200
                Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:13 +0200
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 21:10 +0200
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:25 +0200
                Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 20:44 +0000
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 23:26 +0200
                Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-01 21:08 -0600
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:19 +0200
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:39 +0200
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:34 +0200
                Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:14 +0200
                Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:18 +0200
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 15:21 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 04:09 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 07:48 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 05:49 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 07:52 +0200
                Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 06:46 +0000
                Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 10:59 +0200
              Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 13:39 +0200
                Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-03 13:23 +0000
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-03 15:38 +0200
                Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-03 14:51 +0000
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-04 09:49 +0200
                Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 21:47 +0200
                Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-04 09:53 +0200
                Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 21:52 +0200
            Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:39 +0200
        Re: alloca()-support James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-30 21:36 -0400
      Re: alloca()-support Philipp Klaus Krause <pkk@spth.de> - 2019-09-30 19:14 +0200
        Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 19:16 +0200
          Re: alloca()-support Robert Wessel <robertwessel2@yahoo.com> - 2019-10-01 00:18 -0500
            Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:43 +0200
            Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-10-01 02:42 -0700
              Re: alloca()-support James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-10-01 08:11 -0400
              Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 14:53 +0200
      Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 17:52 +0000
    Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-09-30 11:20 -0600
      Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 19:42 +0200
        Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 20:02 +0200
      Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 19:54 +0200
        Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-09-30 14:28 -0600
          Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 09:38 +0200
      Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 20:01 +0200
        Re: alloca()-support Manfred <noname@add.invalid> - 2019-10-01 17:45 +0200
  Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 00:03 -0700
    Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-10-02 11:30 +0300
    Re: alloca()-support Ian Collins <ian-news@hotmail.com> - 2019-10-02 21:34 +1300
      Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 01:36 -0700
        Re: alloca()-support Ian Collins <ian-news@hotmail.com> - 2019-10-02 21:41 +1300
          Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 02:28 -0700
  Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-02 02:35 -0700
    Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 02:43 -0700
    Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 16:26 +0300
      Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-02 12:33 -0700
        Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-03 01:47 +0300
          Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-05 14:08 -0700

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