Re: Constant Stack Canaries

From	BGB <cr88192@gmail.com>
Newsgroups	comp.arch
Subject	Re: Constant Stack Canaries
Date	2025-04-01 23:19 -0500
Organization	A noiseless patient Spider
Message-ID	<vsidun$sput$2@dont-email.me> (permalink)
References	(6 earlier) <vseojq$112f7$1@dont-email.me> <62b5c4a25d917c5bab64a815189de826@www.novabbs.org> <vshf6a$3smcv$1@dont-email.me> <21397906a7a77c2d43191fdaab98a3c9@www.novabbs.org> <jwv4iz75l6k.fsf-monnier+comp.arch@gnu.org>

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On 4/1/2025 9:55 PM, Stefan Monnier wrote:
>>> Say, if you load a single copy of a binary at 0x24680000.
>>> Process A and B can't use the same mapping in the same address space,
>>> with PC-rel globals, as then they would each see the other's globals.
>>
>> Say I load a copy of the binary text at 0x24680000 and its data at
>> 0x35900000 for a distance of 0x11280000 into the address space of
>> a process.
>>
>> Then I load another copy at 0x44680000 and its data at 55900000
>> into the address space of a different process.
> 
> But then if thread A (whose state is stored at 0x35900000) sends to
> thread B (whose state is at 55900000) a closure whose code points
> somewhere inside 0x24680000, it will end up using the state of thread
> A instead of the state of the current thread.
> 

Generally, threads and processes are seen as different...

But, yeah, passing lambdas between processes is theoretically possible 
in this scheme, but not advised.

If done, any pointers captured by the lambda would likely point to the 
originating process, but if called with a GBR from the new process, any 
global variables would either be mapped to the corresponding DLL index 
in the new process, or NULL (if a DLL that was not loaded in the new 
process), or  possibly a random address if it was from the main EXE and 
the EXE's differ...

But, yeah, inter-process function pointers aren't really a thing, and 
should not be a thing.

The eventual plan is to disallow them in the memory protection scheme, 
but enforcing memory access based the ACL based memory protection is 
still on the TODO list (it was only very recently that stuff is actually 
running in a proper usermode and so can't just stomp all over the 
kernel's memory...).

But... Yeah, the kernel and program are still hanging out in the same 
VAS, along with every other running program...

Thread

Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-03-30 08:16 -0400
  Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-30 12:47 -0500
    Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-30 20:14 +0000
      Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-03-30 21:26 -0400
      Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 01:34 -0500
      Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-03-31 09:04 -0700
        Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 12:17 -0500
          Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-03-31 10:57 -0700
          Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-31 18:07 +0000
            Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-03-31 13:56 -0500
              Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-03-31 20:52 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 00:58 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 18:51 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 18:06 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 23:24 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 20:07 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-02 01:47 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-04 21:07 +0000
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 16:21 -0500
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-01 18:19 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 23:04 -0500
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 14:34 -0500
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-01 23:21 +0000
                Re: Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-01 22:55 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-01 23:19 -0500
                Re: Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-03 10:09 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-03 12:22 -0500
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-03 23:49 -0400
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-04 12:41 -0500
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-04 21:13 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-04 23:45 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 16:37 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-05 18:31 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-05 17:57 -0400
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 23:11 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-06 14:21 +0000
                Re: Constant Stack Canaries Robert Finch <robfi680@gmail.com> - 2025-04-06 15:01 -0400
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-07 14:04 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-05 23:06 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-06 14:32 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-07 00:51 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-07 14:09 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-09 00:23 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-15 00:43 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-15 14:02 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-15 20:46 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-16 14:07 +0000
                Re: Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-16 21:13 +0000
                Virtualization layers (was: Constant Stack Canaries) Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-16 17:48 -0400
                Re: Virtualization layers mitchalsup@aol.com (MitchAlsup1) - 2025-04-16 22:12 +0000
                Re: Virtualization layers (was: Constant Stack Canaries) scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:49 +0000
                Re: Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-04-16 15:26 -0700
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:57 +0000
                Re: virtualization, Constant Stack Canaries John Levine <johnl@taugh.com> - 2025-04-17 01:04 +0000
                Re: virtualization, Constant Stack Canaries Stefan Monnier <monnier@iro.umontreal.ca> - 2025-04-16 21:07 -0400
                Re: virtualization, Constant Stack Canaries Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2025-04-16 23:30 -0700
                Re: virtualization, Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 13:32 +0000
                Re: virtualization, Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-17 18:22 +0000
                Re: virtualization, Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 20:10 +0000
                Re: virtualization, Constant Stack Canaries mitchalsup@aol.com (MitchAlsup1) - 2025-04-17 21:45 +0000
                Re: Constant Stack Canaries scott@slp53.sl.home (Scott Lurndal) - 2025-04-17 00:47 +0000
                Re: Constant Stack Canaries BGB <cr88192@gmail.com> - 2025-04-02 00:43 -0500

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