[PATCH] staging: greybus: Replace sprintf with sysfs_emit

[PATCH] staging: greybus: Replace sprintf with sysfs_emit

[Mohammad Davoudi]

Replace sprintf() with sysfs_emit() in sysfs show functions.
The sprintf() function is unaware of the PAGE_SIZE limit of the sysfs
buffer, which can potentially lead to buffer overruns. sysfs_emit()
is strictly designed for sysfs attributes and inherently protects
against buffer boundaries.

Signed-off-by: Mohammad Davoudi <MDavoudi2011@gmail.com>
---
 drivers/staging/greybus/gbphy.c | 2 +-
 drivers/staging/greybus/light.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/greybus/gbphy.c b/drivers/staging/greybus/gbphy.c
index bdb0f5164..bb9a5b538 100644
--- a/drivers/staging/greybus/gbphy.c
+++ b/drivers/staging/greybus/gbphy.c
@@ -31,7 +31,7 @@ static ssize_t protocol_id_show(struct device *dev,
 {
 	struct gbphy_device *gbphy_dev = to_gbphy_dev(dev);
 
-	return sprintf(buf, "0x%02x\n", gbphy_dev->cport_desc->protocol_id);
+	return sysfs_emit(buf, "0x%02x\n", gbphy_dev->cport_desc->protocol_id);
 }
 static DEVICE_ATTR_RO(protocol_id);
 
diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index cab02b5da..2689f9a75 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -173,7 +173,7 @@ static ssize_t fade_##__dir##_show(struct device *dev,			\
 	struct led_classdev *cdev = dev_get_drvdata(dev);		\
 	struct gb_channel *channel = get_channel_from_cdev(cdev);	\
 									\
-	return sprintf(buf, "%u\n", channel->fade_##__dir);		\
+	return sysfs_emit(buf, "%u\n", channel->fade_##__dir);		\
 }									\
 									\
 static ssize_t fade_##__dir##_store(struct device *dev,			\
@@ -220,7 +220,7 @@ static ssize_t color_show(struct device *dev, struct device_attribute *attr,
 	struct led_classdev *cdev = dev_get_drvdata(dev);
 	struct gb_channel *channel = get_channel_from_cdev(cdev);
 
-	return sprintf(buf, "0x%08x\n", channel->color);
+	return sysfs_emit(buf, "0x%08x\n", channel->color);
 }
 
 static ssize_t color_store(struct device *dev, struct device_attribute *attr,
-- 
2.43.0

Re: [PATCH] staging: greybus: Replace sprintf with sysfs_emit

[Dan Carpenter]

On Wed, Jul 15, 2026 at 05:28:58PM +0000, Mohammad Davoudi wrote:
> Replace sprintf() with sysfs_emit() in sysfs show functions.
> The sprintf() function is unaware of the PAGE_SIZE limit of the sysfs
> buffer, which can potentially lead to buffer overruns. sysfs_emit()
> is strictly designed for sysfs attributes and inherently protects
> against buffer boundaries.
> 
> Signed-off-by: Mohammad Davoudi <MDavoudi2011@gmail.com>

We're not applying this kind of patch in cases where sprintf is fine.

Really, I never like commit messages which talk about "potential
buffer overruns".  Is it a buffer overrun or not?  If it's really
hard to figure out then say that "This code is really hard to figure
out and I suspect its fine but let's be safe."

In this case the code is really simple and we can all see the original
code is fine just from reading the diff...

regards,
dan carpenter

Re: [PATCH] staging: greybus: Replace sprintf with sysfs_emit

[David Laight]

On Thu, 16 Jul 2026 00:31:35 +0300
Dan Carpenter <error27@gmail.com> wrote:

> On Wed, Jul 15, 2026 at 05:28:58PM +0000, Mohammad Davoudi wrote:
> > Replace sprintf() with sysfs_emit() in sysfs show functions.
> > The sprintf() function is unaware of the PAGE_SIZE limit of the sysfs
> > buffer, which can potentially lead to buffer overruns. sysfs_emit()
> > is strictly designed for sysfs attributes and inherently protects
> > against buffer boundaries.
> > 
> > Signed-off-by: Mohammad Davoudi <MDavoudi2011@gmail.com>  
> 
> We're not applying this kind of patch in cases where sprintf is fine.
> 
> Really, I never like commit messages which talk about "potential
> buffer overruns".  Is it a buffer overrun or not?  If it's really
> hard to figure out then say that "This code is really hard to figure
> out and I suspect its fine but let's be safe."
> 
> In this case the code is really simple and we can all see the original
> code is fine just from reading the diff...

And you also have to double-check that it is valid to call sysfs_emit()
in that context.
The call sequences aren't all that obvious and are difficult to verify.

	David

> 
> regards,
> dan carpenter
> 
>