linux-kernel - [PATCH] staging: wlan-ng: replace strncpy() with strscpy()

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Date:   Mon, 16 Oct 2023 09:39:33 +0300
From:   Calvince Otieno <calvncce@...il.com>
To:     gustavo@...eddedor.com, outreachy@...ts.linux.dev
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Calvince Otieno <calvncce@...il.com>,
        Dan Carpenter <dan.carpenter@...aro.org>
Subject: [PATCH] staging: wlan-ng: replace strncpy() with strscpy()

Checkpatch suggests the use of strscpy() instead of strncpy().
The advantages are that it always adds a NUL terminator and it prevents
a read overflow if the src string is not properly terminated. One
potential disadvantage is that it doesn't zero pad the string like
strncpy() does.
In this code, strscpy() and strncpy() are equivalent and it does not
affect runtime behavior. The string is zeroed on the line before
using memset(). The resulting string was always NUL terminated and
PRISM2_USB_FWFILE is string literal "prism2_ru.fw" so it's NUL
terminated.
However, even though using strscpy() does not fix any bugs, it's
still nicer and makes checkpatch happy.

Signed-off-by: Calvince Otieno <calvncce@...il.com>
---
Previous Patch Versions:
 - Earlier patch versions had issues with whitespace, preventing correct
 application. This is a reroll of those previous versions.

 - Versions v2 through v6 focused on improving the clarity of the commit
 message. There were no code changes in these patch versions.

 drivers/staging/wlan-ng/prism2fw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/wlan-ng/prism2fw.c b/drivers/staging/wlan-ng/prism2fw.c
index 5d03b2b9aab4..3ccd11041646 100644
--- a/drivers/staging/wlan-ng/prism2fw.c
+++ b/drivers/staging/wlan-ng/prism2fw.c
@@ -725,7 +725,7 @@ static int plugimage(struct imgchunk *fchunk, unsigned int nfchunks,

 		if (j == -1) {	/* plug the filename */
 			memset(dest, 0, s3plug[i].len);
-			strncpy(dest, PRISM2_USB_FWFILE, s3plug[i].len - 1);
+			strscpy(dest, PRISM2_USB_FWFILE, s3plug[i].len);
 		} else {	/* plug a PDR */
 			memcpy(dest, &pda->rec[j]->data, s3plug[i].len);
 		}
-- 
2.34.1