[PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[Thorsten Blum]

strncpy() is deprecated for NUL-terminated destination buffers. Use
strscpy() instead and remove the manual NUL-termination.

Compile-tested only.

Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 arch/m68k/kernel/setup_mm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
index 15c1a595a1de..48ce67947678 100644
--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c
@@ -243,8 +243,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_initial_init_mm((void *)PAGE_OFFSET, _etext, _edata, _end);
 
 #if defined(CONFIG_BOOTPARAM)
-	strncpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
-	m68k_command_line[CL_SIZE - 1] = 0;
+	strscpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
 #endif /* CONFIG_BOOTPARAM */
 	process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
 	*cmdline_p = m68k_command_line;
-- 
2.48.1

Re: [PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[Jean-Michel Hautbois]

Hi Thorsten,

On 2/13/25 3:10 PM, Thorsten Blum wrote:
> strncpy() is deprecated for NUL-terminated destination buffers. Use
> strscpy() instead and remove the manual NUL-termination.
> 
> Compile-tested only.
> 
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

Thanks for the patch !
It works fine for me:

Tested-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
> ---
>   arch/m68k/kernel/setup_mm.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
> index 15c1a595a1de..48ce67947678 100644
> --- a/arch/m68k/kernel/setup_mm.c
> +++ b/arch/m68k/kernel/setup_mm.c
> @@ -243,8 +243,7 @@ void __init setup_arch(char **cmdline_p)
>   	setup_initial_init_mm((void *)PAGE_OFFSET, _etext, _edata, _end);
>   
>   #if defined(CONFIG_BOOTPARAM)
> -	strncpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
> -	m68k_command_line[CL_SIZE - 1] = 0;
> +	strscpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
>   #endif /* CONFIG_BOOTPARAM */
>   	process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
>   	*cmdline_p = m68k_command_line;

Re: [PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[Geert Uytterhoeven]

On Thu, 13 Feb 2025 at 15:11, Thorsten Blum <thorsten.blum@linux.dev> wrote:
> strncpy() is deprecated for NUL-terminated destination buffers. Use
> strscpy() instead and remove the manual NUL-termination.
>
> Compile-tested only.
>
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>

> --- a/arch/m68k/kernel/setup_mm.c
> +++ b/arch/m68k/kernel/setup_mm.c
> @@ -243,8 +243,7 @@ void __init setup_arch(char **cmdline_p)
>         setup_initial_init_mm((void *)PAGE_OFFSET, _etext, _edata, _end);
>
>  #if defined(CONFIG_BOOTPARAM)
> -       strncpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
> -       m68k_command_line[CL_SIZE - 1] = 0;
> +       strscpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
>  #endif /* CONFIG_BOOTPARAM */
>         process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
>         *cmdline_p = m68k_command_line;

This seems to be used mostly by Coldfire, so I'll let Greg handle it.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[Greg Ungerer]

Hi Thorsten,

On 19/2/25 00:13, Geert Uytterhoeven wrote:
> On Thu, 13 Feb 2025 at 15:11, Thorsten Blum <thorsten.blum@linux.dev> wrote:
>> strncpy() is deprecated for NUL-terminated destination buffers. Use
>> strscpy() instead and remove the manual NUL-termination.
>>
>> Compile-tested only.
>>
>> Link: https://github.com/KSPP/linux/issues/90
>> Cc: linux-hardening@vger.kernel.org
>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> 
> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
> 
>> --- a/arch/m68k/kernel/setup_mm.c
>> +++ b/arch/m68k/kernel/setup_mm.c
>> @@ -243,8 +243,7 @@ void __init setup_arch(char **cmdline_p)
>>          setup_initial_init_mm((void *)PAGE_OFFSET, _etext, _edata, _end);
>>
>>   #if defined(CONFIG_BOOTPARAM)
>> -       strncpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
>> -       m68k_command_line[CL_SIZE - 1] = 0;
>> +       strscpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
>>   #endif /* CONFIG_BOOTPARAM */
>>          process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
>>          *cmdline_p = m68k_command_line;
> 
> This seems to be used mostly by Coldfire, so I'll let Greg handle it.

Looks good. Pushed into the m68knommu git tree, for-next branch, with
JM's tested-by and Geert's reviewed-by added.

Thanks
Greg

Re: [PATCH] m68k: mm: Replace deprecated strncpy() with strscpy()

[Kees Cook]

On Thu, Feb 13, 2025 at 03:10:36PM +0100, Thorsten Blum wrote:
> strncpy() is deprecated for NUL-terminated destination buffers. Use
> strscpy() instead and remove the manual NUL-termination.
> 
> Compile-tested only.
> 
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  arch/m68k/kernel/setup_mm.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
> index 15c1a595a1de..48ce67947678 100644
> --- a/arch/m68k/kernel/setup_mm.c
> +++ b/arch/m68k/kernel/setup_mm.c
> @@ -243,8 +243,7 @@ void __init setup_arch(char **cmdline_p)
>  	setup_initial_init_mm((void *)PAGE_OFFSET, _etext, _edata, _end);
>  
>  #if defined(CONFIG_BOOTPARAM)
> -	strncpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
> -	m68k_command_line[CL_SIZE - 1] = 0;
> +	strscpy(m68k_command_line, CONFIG_BOOTPARAM_STRING, CL_SIZE);
>  #endif /* CONFIG_BOOTPARAM */
>  	process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
>  	*cmdline_p = m68k_command_line;

m68k_command_line lives in rwdata, so it should be 0-initialized by
default, so there should be no behavioral difference here (i.e. it will
be zero-padded), and it is used as a C String, so there was unlikely to
be anything depending on the NUL-padding.

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook