Re: Memory protection between compilation units?

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: Memory protection between compilation units?
Date	2025-06-16 06:10 -0700
Organization	A noiseless patient Spider
Message-ID	<86jz5bq1bd.fsf@linuxsc.com> (permalink)
References	(5 earlier) <20250613165623.00004eb3@yahoo.com> <102kq3e$e9ts$1@dont-email.me> <102mjh5$31ckr$1@paganini.bofh.team> <102nab5$148mb$1@dont-email.me> <102nm7l$3333o$1@paganini.bofh.team>

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antispam@fricas.org (Waldek Hebisch) writes:

> Mateusz Viste <mateusz@not.gonna.tell> wrote:
>
>> That said, detecting out-of-bounds array access is no panacea.  Memory
>> corruption can arise from various sources, such as dangling pointers or
>> poorly managed pointer arithmetic.
>
> AFAICS there is no reason for explicit pointer arithmetic in well
> written C programs.

This assertion is in effect a No True Scotsman statement.

> Implicit pointer arithmetic (coming from array
> indexing) is done by compiler so should be no problem.

Even if there is no direct manipulation ("pointer arithmetic") of
pointer variables, access can be checked only if array bounds
information is available, and in many cases it isn't.  The reason is
(among other things) C doesn't have array parameters;  what it does
have instead is pointer parameters.  At the point in the code when
an "array" access is to be done, the information needed to check
that an index value is in bounds just isn't available.  The culprit
here is not explicit pointer arithmetic, but lacking the information
needed to do a bounds check.  That lack is inherent in how the C
language works with respect to arrays and pointer conversion.

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Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-11 15:32 +0200
  Re: Memory protection between compilation units? Josef Möllers <josef@invalid.invalid> - 2025-06-11 16:06 +0200
    Re: Memory protection between compilation units? scott@slp53.sl.home (Scott Lurndal) - 2025-06-11 14:32 +0000
      Re: Memory protection between compilation units? Michael S <already5chosen@yahoo.com> - 2025-06-12 20:01 +0300
        Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-13 09:13 +0200
      Re: Memory protection between compilation units? Richard Heathfield <rjh@cpax.org.uk> - 2025-06-12 19:15 +0100
        Re: Memory protection between compilation units? Rosario19 <Ros@invalid.invalid> - 2025-06-16 18:14 +0200
          Re: Memory protection between compilation units? Richard Heathfield <rjh@cpax.org.uk> - 2025-06-16 17:53 +0100
  Re: Memory protection between compilation units? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2025-06-11 14:30 +0000
  Re: Memory protection between compilation units? David Brown <david.brown@hesbynett.no> - 2025-06-11 17:14 +0200
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-12 14:31 +0200
      Re: Memory protection between compilation units? David Brown <david.brown@hesbynett.no> - 2025-06-12 15:29 +0200
        Re: Memory protection between compilation units? scott@slp53.sl.home (Scott Lurndal) - 2025-06-12 14:27 +0000
  Re: Memory protection between compilation units? Opus <ifonly@youknew.org> - 2025-06-11 17:19 +0200
    Re: Memory protection between compilation units? wij <wyniijj5@gmail.com> - 2025-06-11 23:38 +0800
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-12 14:41 +0200
      Re: Memory protection between compilation units? scott@slp53.sl.home (Scott Lurndal) - 2025-06-12 13:21 +0000
  Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-11 15:36 +0000
  Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-12 10:28 +0200
    Re: Memory protection between compilation units? scott@slp53.sl.home (Scott Lurndal) - 2025-06-12 13:18 +0000
    Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-12 18:59 +0000
      Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-13 08:42 +0200
        Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-13 16:17 +0000
      Re: Memory protection between compilation units? pozz <pozzugno@gmail.com> - 2025-06-13 09:21 +0200
        Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-13 14:14 +0200
          Re: Memory protection between compilation units? Michael S <already5chosen@yahoo.com> - 2025-06-13 16:56 +0300
            Re: Memory protection between compilation units? Richard Heathfield <rjh@cpax.org.uk> - 2025-06-13 15:43 +0100
              Re: Memory protection between compilation units? Michael S <already5chosen@yahoo.com> - 2025-06-14 22:07 +0300
            Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-13 17:14 +0000
            Re: Memory protection between compilation units? Mateusz Viste <mateusz@not.gonna.tell> - 2025-06-14 21:37 +0000
              Re: Memory protection between compilation units? antispam@fricas.org (Waldek Hebisch) - 2025-06-15 13:57 +0000
                Re: Memory protection between compilation units? Mateusz Viste <mateusz@not.gonna.tell> - 2025-06-15 20:27 +0000
                Re: Memory protection between compilation units? antispam@fricas.org (Waldek Hebisch) - 2025-06-15 23:50 +0000
                Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-16 01:01 +0000
                Re: Memory protection between compilation units? antispam@fricas.org (Waldek Hebisch) - 2025-06-16 10:00 +0000
                Re: Memory protection between compilation units? James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-06-16 06:12 -0400
                Re: Memory protection between compilation units? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-16 06:10 -0700
                Re: Memory protection between compilation units? antispam@fricas.org (Waldek Hebisch) - 2025-06-16 16:47 +0000
          Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-13 16:23 +0000
          Re: Memory protection between compilation units? wij <wyniijj5@gmail.com> - 2025-06-14 02:10 +0800
  Re: Memory protection between compilation units? Mikko <mikko.levanto@iki.fi> - 2025-06-12 11:40 +0300
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-12 11:05 +0200
  Re: Memory protection between compilation units? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-12 06:05 -0700
    Re: Memory protection between compilation units? Bonita Montero <Bonita.Montero@gmail.com> - 2025-06-13 08:03 +0200
      Re: Memory protection between compilation units? wij <wyniijj5@gmail.com> - 2025-06-14 02:16 +0800
        Re: Memory protection between compilation units? Bonita Montero <Bonita.Montero@gmail.com> - 2025-06-13 20:43 +0200
        Re: Memory protection between compilation units? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-06-13 12:32 -0700
          Re: Memory protection between compilation units? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-13 15:48 -0700
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-13 08:59 +0200
      Re: Memory protection between compilation units? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-13 16:31 -0700
        Re: Memory protection between compilation units? Mateusz Viste <mateusz@not.gonna.tell> - 2025-06-14 22:22 +0000
          Re: Memory protection between compilation units? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-07-01 09:54 -0700
  Re: Memory protection between compilation units? Bonita Montero <Bonita.Montero@gmail.com> - 2025-06-13 08:00 +0200
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-13 08:47 +0200
      Re: Memory protection between compilation units? Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-13 16:19 +0000
  Re: Memory protection between compilation units? Louis Krupp <lkrupp@invalid.pssw.com.invalid> - 2025-06-16 06:29 -0600
    Re: Memory protection between compilation units? Mateusz Viste <mateusz@x.invalid> - 2025-06-16 15:01 +0200
  Re: Memory protection between compilation units? olcott <polcott333@gmail.com> - 2025-06-21 15:49 -0500

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