linux-kernel - [PATCH 4.14 86/89] staging: speakup: Replace strncpy with memcpy

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Date:   Fri, 14 Dec 2018 13:00:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Samuel Thibault <samuel.thibault@...-lyon.org>
Subject: [PATCH 4.14 86/89] staging: speakup: Replace strncpy with memcpy

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guenter Roeck <linux@...ck-us.net>

commit fd29edc7232bc19f969e8f463138afc5472b3d5f upstream.

gcc 8.1.0 generates the following warnings.

drivers/staging/speakup/kobjects.c: In function 'punc_store':
drivers/staging/speakup/kobjects.c:522:2: warning:
	'strncpy' output truncated before terminating nul
	copying as many bytes from a string as its length
drivers/staging/speakup/kobjects.c:504:6: note: length computed here

drivers/staging/speakup/kobjects.c: In function 'synth_store':
drivers/staging/speakup/kobjects.c:391:2: warning:
	'strncpy' output truncated before terminating nul
	copying as many bytes from a string as its length
drivers/staging/speakup/kobjects.c:388:8: note: length computed here

Using strncpy() is indeed less than perfect since the length of data to
be copied has already been determined with strlen(). Replace strncpy()
with memcpy() to address the warning and optimize the code a little.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Reviewed-by: Samuel Thibault <samuel.thibault@...-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/staging/speakup/kobjects.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/staging/speakup/kobjects.c
+++ b/drivers/staging/speakup/kobjects.c
@@ -387,7 +387,7 @@ static ssize_t synth_store(struct kobjec
 	len = strlen(buf);
 	if (len < 2 || len > 9)
 		return -EINVAL;
-	strncpy(new_synth_name, buf, len);
+	memcpy(new_synth_name, buf, len);
 	if (new_synth_name[len - 1] == '\n')
 		len--;
 	new_synth_name[len] = '\0';
@@ -518,7 +518,7 @@ static ssize_t punc_store(struct kobject
 		return -EINVAL;
 	}
 
-	strncpy(punc_buf, buf, x);
+	memcpy(punc_buf, buf, x);
 
 	while (x && punc_buf[x - 1] == '\n')
 		x--;