sprintf, snprintf, and scnprintf do not consider the PAGE_SIZE maximum
of the temporary buffer used for outputting sysfs content and they may
overrun the PAGE_SIZE buffer length.

To avoid output defects with the ATA transport class simple attributes,
use sysfs_emit instead of scnprintf().

This aligns with the sysfs guidance provided in
Documentation/filesystems/sysfs.rst.

Signed-off-by: Jonathan Velez <jonvelez12345@gmail.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/ata/libata-transport.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
index e898be49df6b..62415fe67a11 100644
--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -202,7 +202,7 @@ show_ata_port_##name(struct device *dev,				\
 {									\
 	struct ata_port *ap = transport_class_to_port(dev);		\
 									\
-	return scnprintf(buf, 20, format_string, cast ap->field);	\
+	return sysfs_emit(buf, format_string, cast ap->field);	        \
 }
 
 #define ata_port_simple_attr(field, name, format_string, type)		\
@@ -389,7 +389,7 @@ show_ata_dev_##field(struct device *dev,				\
 {									\
 	struct ata_device *ata_dev = transport_class_to_dev(dev);	\
 									\
-	return scnprintf(buf, 20, format_string, cast ata_dev->field);	\
+	return sysfs_emit(buf, format_string, cast ata_dev->field);	\
 }
 
 #define ata_dev_simple_attr(field, format_string, type)		\
-- 
2.43.0

On Wed, 09 Jul 2025 13:33:30 +0000, Jonathan Velez wrote:
> sprintf, snprintf, and scnprintf do not consider the PAGE_SIZE maximum
> of the temporary buffer used for outputting sysfs content and they may
> overrun the PAGE_SIZE buffer length.
> 
> To avoid output defects with the ATA transport class simple attributes,
> use sysfs_emit instead of scnprintf().
> 
> [...]

Applied to libata/linux.git (for-6.17), thanks!

[1/1] ata: libata-transport: replace scnprintf with sysfs_emit for simple attributes
      https://git.kernel.org/libata/linux/c/48925ba7

Kind regards,
Niklas

Hello Jonathan,

You forgot to use -v 2 to git format-patch (so that v2 is in the subject),
and you forgot to add a changelog (changes since v1) after the '---'.

No need to resend, but until next time.

Thank you for your contribution.


Kind regards,
Niklas


On Wed, Jul 09, 2025 at 01:33:30PM +0000, Jonathan Velez wrote:
> sprintf, snprintf, and scnprintf do not consider the PAGE_SIZE maximum
> of the temporary buffer used for outputting sysfs content and they may
> overrun the PAGE_SIZE buffer length.
> 
> To avoid output defects with the ATA transport class simple attributes,
> use sysfs_emit instead of scnprintf().
> 
> This aligns with the sysfs guidance provided in
> Documentation/filesystems/sysfs.rst.
> 
> Signed-off-by: Jonathan Velez <jonvelez12345@gmail.com>
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> ---
>  drivers/ata/libata-transport.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
> index e898be49df6b..62415fe67a11 100644
> --- a/drivers/ata/libata-transport.c
> +++ b/drivers/ata/libata-transport.c
> @@ -202,7 +202,7 @@ show_ata_port_##name(struct device *dev,				\
>  {									\
>  	struct ata_port *ap = transport_class_to_port(dev);		\
>  									\
> -	return scnprintf(buf, 20, format_string, cast ap->field);	\
> +	return sysfs_emit(buf, format_string, cast ap->field);	        \
>  }
>  
>  #define ata_port_simple_attr(field, name, format_string, type)		\
> @@ -389,7 +389,7 @@ show_ata_dev_##field(struct device *dev,				\
>  {									\
>  	struct ata_device *ata_dev = transport_class_to_dev(dev);	\
>  									\
> -	return scnprintf(buf, 20, format_string, cast ata_dev->field);	\
> +	return sysfs_emit(buf, format_string, cast ata_dev->field);	\
>  }
>  
>  #define ata_dev_simple_attr(field, format_string, type)		\
> -- 
> 2.43.0
>