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[1/8] loop: use sysfs_emit() in the sysfs offset show

Message ID 20210921092123.13632-2-chaitanyak@nvidia.com (mailing list archive)
State New, archived
Headers show
Series loop: small clenaup | expand

Commit Message

Chaitanya Kulkarni Sept. 21, 2021, 9:21 a.m. UTC 
From: Chaitanya Kulkarni <kch@nvidia.com>

Output defects can exist in sysfs content using sprintf and snprintf.

sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.

Use a generic sysfs_emit function that knows that the size of the
temporary buffer and ensures that no overrun is done for offset
attribute.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
---
 drivers/block/loop.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Himanshu Madhani Sept. 21, 2021, 1:33 p.m. UTC | #1 
> On Sep 21, 2021, at 4:21 AM, Chaitanya Kulkarni <chaitanyak@nvidia.com> wrote:
> 
> From: Chaitanya Kulkarni <kch@nvidia.com>
> 
> Output defects can exist in sysfs content using sprintf and snprintf.
> 

Small nit.. I would remove above line from patch 1 - 5. 

Below commit message describes it better.
 

> sprintf does not know the PAGE_SIZE maximum of the temporary buffer
> used for outputting sysfs content and it's possible to overrun the
> PAGE_SIZE buffer length.
> 
> Use a generic sysfs_emit function that knows that the size of the

Also in above line, I would remove second “that” (same for patches 1 - 5)

> temporary buffer and ensures that no overrun is done for offset
> attribute.
> 
> Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> ---
> drivers/block/loop.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 7bf4686af774..e37444977ae6 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -856,7 +856,7 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
> 
> static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
> {
> -	return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
> +	return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
> }
> 
> static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
> -- 
> 2.29.0
> 

Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>

--
Himanshu Madhani	 Oracle Linux Engineering
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Patch

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7bf4686af774..e37444977ae6 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -856,7 +856,7 @@  static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
 
 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
 {
-	return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
+	return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
 }
 
 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)