[Bug gdb/17785] New: GDB ignores "disable-randomization" setting once its set to off once

[Bug gdb/17785] New: GDB ignores "disable-randomization" setting once its set to off once

[dman79 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17785

            Bug ID: 17785
           Summary: GDB ignores "disable-randomization" setting once its
                    set to off once
           Product: gdb
           Version: 7.7
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: dman79 at gmail dot com

I've recreated this in a few times installed xubuntu then linuxlite.. once you
set disable-randomization to off it will from now on ignore the setting
you can set it to on and it will show on but memory/stack will be randomized
from now on.

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[Bug gdb/17785] GDB ignores "disable-randomization" setting once its set to off once

[xdje42 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17785

Doug Evans <xdje42 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xdje42 at gmail dot com

--- Comment #1 from Doug Evans <xdje42 at gmail dot com> ---
Repro instructions please.
Looking at the code (linux_nat_create_inferior) I see it doesn't protect itself
from an error thrown by to_create_inferior.  Maybe to_create_inferior can't
throw an error (in which case no protection is needed) but that'd be a bit
fragile.  OTOH, even if personality didn't get restored, the next time through
should turn on ADDR_NO_RANDOMIZE if disable_randomization is set.

Thus it's hard reason about this bug without reproduction instructions.
Got repro?

I tried the following, and could not reproduce the problem:

bash$ gdb hello.x64
...
(gdb) set confirm off
(gdb) show disable
Disabling randomization of debuggee's virtual address space is on.
(gdb) start
Temporary breakpoint 1 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 1, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$1 = (void *) 0x7fffffffe1c0
(gdb) start
Temporary breakpoint 2 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 2, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$2 = (void *) 0x7fffffffe1c0
(gdb) set disable off
(gdb) start
Temporary breakpoint 3 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 3, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$3 = (void *) 0x7fffe7de8020
(gdb) start
Temporary breakpoint 4 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 4, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$4 = (void *) 0x7fff2fbd7fe0
(gdb) set disable on
(gdb) start
Temporary breakpoint 5 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 5, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$5 = (void *) 0x7fffffffe1c0
(gdb) start
Temporary breakpoint 6 at 0x400764: file hello.cc, line 6.
Starting program: /home/dje/hello.x64

Temporary breakpoint 6, main () at hello.cc:6
6         std::cout << "hello\n";
(gdb) p $rsp
$6 = (void *) 0x7fffffffe1c0
(gdb)

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[Bug gdb/17785] GDB ignores "disable-randomization" setting once its set to off once

[dman79 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17785

--- Comment #2 from dman79 at gmail dot com ---
Reproducing the problem is simple  gdb myprogram
show disable-randomization
set disable-randomization on
quit

gdb myprogram
b *main
r
x/x $esp
r
x/x $esp
show disable-randomization

which will be on but $esp will be randomized on each single run.

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[Bug gdb/17785] GDB ignores "disable-randomization" setting once its set to off once

[xdje42 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=17785

--- Comment #3 from Doug Evans <xdje42 at gmail dot com> ---
(In reply to dman79 from comment #2)
> Reproducing the problem is simple  gdb myprogram
> show disable-randomization
> set disable-randomization on
> quit
> 
> gdb myprogram
> b *main
> r
> x/x $esp
> r
> x/x $esp
> show disable-randomization
> 
> which will be on but $esp will be randomized on each single run.

Did you mean "set disable-randomization" off in the above example?

Plus, are you saying that enabling randomization *** in a separate ***
gdb session then enabled randomization for all subsequent gdb sessions?
If so, that's a kernel bug.

I still can't reproduce the problem.
Let's first pin down your repro.
Can you paste an unedited session log, starting from the shell command that
launches gdb?

And, on the off chance (seems unlikely, but who knows), what's your kernel
version?

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[Bug gdb/17785] GDB ignores "disable-randomization" setting once its set to off once

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=17785

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
                 CC|                            |tromey at sourceware dot org
             Status|NEW                         |RESOLVED

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
Years without a response, I suspect this isn't a bug.

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