[Bug middle-end/113694] New: Allow renaming stack smashing protector symbols

[Bug middle-end/113694] New: Allow renaming stack smashing protector symbols

[matheus.a.m.moreira at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

            Bug ID: 113694
           Summary: Allow renaming stack smashing protector symbols
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: matheus.a.m.moreira at gmail dot com
  Target Milestone: ---

I'm writing freestanding Linux applications which are compiled with
-ffreestanding -nostdlib. In order to integrate with the stack smashing
protector, I need to provide the following symbols:

    __stack_chk_guard
    __stack_chk_fail

It would be nice if there was a compiler option to rename these symbols to
something else. I want to make them consistent with the rest of my code,
thereby improving its quality.

A couple of options would be enough:

    -fstack-protector-canary=my_variable
    -fstack-protector-handler=my_function

Attributes could work too:

    uintptr_t my_canary __attribute__((stack_protector_canary));

    __attribute__((noreturn, stack_protector_handler))
    void __stack_chk_fail(void);

[Bug middle-end/113694] Allow renaming stack smashing protector symbols

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

[Bug middle-end/113694] Allow renaming stack smashing protector symbols

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
You could provide an alias to __stack_chk_guard/__stack_chk_fail in your code
though.

[Bug middle-end/113694] Allow renaming stack smashing protector symbols

[matheus.a.m.moreira at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

--- Comment #2 from Matheus Afonso Martins Moreira <matheus.a.m.moreira at gmail dot com> ---
That's true but in that case the __stack_chk_* symbols will remain in the
compiler output and in the final binary. They will show up in readelf output,
GDB function disassemblies.

I think the ability to rename the symbols would be a cleaner solution.
Programmers should have full control over the symbols emitted by the compiler.

[Bug middle-end/113694] Allow renaming stack smashing protector symbols

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sjames at gcc dot gnu.org
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=97119

--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Matheus Afonso Martins Moreira from comment #2)
> Programmers should have full control over the symbols emitted by the
> compiler.

Note that this isn't something GCC offers for other things, e.g. PR97119.

[Bug middle-end/113694] Allow renaming stack smashing protector symbols

[matheus.a.m.moreira at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113694

--- Comment #4 from Matheus Afonso Martins Moreira <matheus.a.m.moreira at gmail dot com> ---
(In reply to Sam James from comment #3)
> Note that this isn't something GCC offers for other things, e.g. PR97119.

GCC does offer it for at least one thing that I'm aware of:

    -e entry
    --entry=entry

    Specify that the program entry point is entry.
    The argument is interpreted by the linker;
    the GNU linker accepts either a symbol name or an address.

With this useful option, I was able to change the somewhat ugly "_start" symbol
to a name of my choosing.