linux-kernel - Re: [PATCH] gendwarfksyms: define __GENKSYMS_

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABCJKuc3zZOG4qgoFca_g80GMkzviVRemGLJB8GaA88u27Mt8A@mail.gmail.com>
Date: Thu, 20 Mar 2025 07:47:46 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Ard Biesheuvel <ardb+git@...gle.com>
Cc: linux-kbuild@...r.kernel.org, brgerst@...il.com, x86@...nel.org, 
	masahiroy@...nel.org, nathan@...nel.org, linux-kernel@...r.kernel.org, 
	nogikh@...gle.com, Ard Biesheuvel <ardb@...nel.org>, 
	syzbot+06fd1a3613c50d36129e@...kaller.appspotmail.com
Subject: Re: [PATCH] gendwarfksyms: define __GENKSYMS__ when processing asm-protoypes.h

Hi Ard,

On Thu, Mar 20, 2025 at 12:07 AM Ard Biesheuvel <ardb+git@...gle.com> wrote:
>
> From: Ard Biesheuvel <ardb@...nel.org>
>
> Ensure that __GENKSYMS__ is #define'd when passing asm/asm-prototypes.h
> through the compiler to capture the exported symbols. This ensures that
> exported symbols such as __ref_stack_chk_guard on x86, which is declared
> conditionally, is visible to the tool.
>
> Otherwise, an error such as the below may be raised, breaking the build
> when CONFIG_GENDWARFKSYMS=y
>
>   <stdin>:4:15: error: use of undeclared identifier '__ref_stack_chk_guard'
>
> Cc: Sami Tolvanen <samitolvanen@...gle.com>
> Reported-by: syzbot+06fd1a3613c50d36129e@...kaller.appspotmail.com
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>  scripts/Makefile.build | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 993708d11874..7855cdc4e763 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -305,6 +305,7 @@ $(obj)/%.rs: $(obj)/%.rs.S FORCE
>  getasmexports =                                                                \
>     { echo "\#include <linux/kernel.h>" ;                               \
>       echo "\#include <linux/string.h>" ;                               \
> +     echo "\#define  __GENKSYMS__" ;                                   \
>       echo "\#include <asm/asm-prototypes.h>" ;                         \
>       $(call getexportsymbols,EXPORT_SYMBOL(\1);) ; }

This works with gendwarfksyms since __GENKSYMS__ is defined after the
EXPORT_SYMBOL() definition, but I'm now getting warnings with
genksyms:

  AS      arch/x86/lib/clear_page_64.o
<stdin>:3:10: warning: "__GENKSYMS__" redefined
<command-line>: note: this is the location of the previous definition

Sami