linux-kernel - [PATCH v3] staging: wlan-ng: remove strncpy() use in favor of strscpy()

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Message-ID: <ZShI4amWv7sdqfse@lab-ubuntu>
Date:   Thu, 12 Oct 2023 22:28:33 +0300
From:   Calvince Otieno <calvncce@...il.com>
To:     outreachy@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Archana <craechal@...il.com>, Dan Carpenter <error27@...il.com>,
        Calvince Otieno <calvncce@...il.com>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v3] staging: wlan-ng: remove strncpy() use in favor of
 strscpy()

In response to the suggestion by Dan Carpenter on the initial patch,
this patch provides a correct usage of the strscpy() in place of the
current strncpy() implementation.

strscpy() copies characters from the source buffer to the destination
buffer until one of the following conditions is met:
	- null-terminator ('\0') is encountered in the source string.
	- specified maximum length of the destination buffer is reached.
	- source buffer is exhausted.
Example:
	char dest[11];
	const char *PRISM2_USB_FWFILE = "prism2_ru.fw";
	strscpy(dest, PRISM2_USB_FWFILE, sizeof(dest));

	In this case, strscpy copies the first 10 characters of src into dest
	and add a null-terminator. dest will then contain "prism2_ru.f" with
	proper null-termination.

Since the specified length of the dest buffer is not derived from the
dest buffer itself and rather form plug length (s3plug[i].len),
replacing strcpy() with strscpy() is a better option because it will
ensures that the destination string is always properly terminated.

Signed-off-by: Calvince Otieno <calvncce@...il.com>
---

Patch version v3:
	Correct the patch subject headline.
	staging: wlan-ng: remove strncpy() use in favor of strscpy()

Patch version v2 :
        Correct implementation of the strscpy()

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);
                }

Patch version v1:
        Replacing strncpy() with strscpy()

 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..57a99dd12143 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 - 1);
                } else {        /* plug a PDR */
                        memcpy(dest, &pda->rec[j]->data, s3plug[i].len);
                }
-- 
Calvince Otieno