Re: [PATCH 4/8] loop: use sysfs_emit() in the sysfs partscan show

On Sep 21, 2021, at 4:21 AM, Chaitanya Kulkarni [off-list ref] wrote:

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 partscan
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 fd935b788c53..63f64341c19c 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c

@@ -875,7 +875,7 @@ static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)

{
	int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);

-	return sprintf(buf, "%s\n", partscan ? "1" : "0");
+	return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
}

static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
-- 
2.29.0