Re: [PATCH v3 09/11] powerpc/papr_scm: Return the string length from the sysfs show functions

[Madhavan Srinivasan <maddy@linux.ibm.com>]

On 10/1/26 5:22 AM, Kees Cook wrote:
> perf_stats_show() and flags_show() build their output with a seq_buf
> and return seq_buf_used(), which may include the trailing NUL byte
> when the seq_buf has overflowed. Use seq_buf_strlen() instead.
>
> Build tested ARCH=powerpc ppc64_defconfig with GCC powerpc64-linux-gnu
> 16.1.0:
> arch/powerpc/platforms/pseries/papr_scm.o
>
> Assisted-by: LLM
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
>   arch/powerpc/platforms/pseries/papr_scm.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index 75da96c08cdd..b03cfd8528f5 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -1108,7 +1108,7 @@ static ssize_t perf_stats_show(struct device *dev,
>   
>   free_stats:
>   	kfree(stats);
> -	return rc ? rc : (ssize_t)seq_buf_used(&s);
> +	return rc ?: (ssize_t)seq_buf_strlen(&s);
>   }
>   static DEVICE_ATTR_ADMIN_RO(perf_stats);
>   
> @@ -1150,7 +1150,7 @@ static ssize_t flags_show(struct device *dev,
>   	if (seq_buf_used(&s))

this can also be seq_buf_strlen instead

>   		seq_buf_printf(&s, "\n");
>   
> -	return seq_buf_used(&s);
> +	return seq_buf_strlen(&s);
>   }
>   DEVICE_ATTR_RO(flags);
>