linux-kernel - [PATCH] staging: speakup: Replace strncpy with memcpy

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Date:   Sun,  1 Jul 2018 13:57:24 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Chris Brannon <chris@...-brannons.com>
Cc:     devel@...verdev.osuosl.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kirk Reiser <kirk@...sers.ca>, linux-kernel@...r.kernel.org,
        Samuel Thibault <samuel.thibault@...-lyon.org>,
        speakup@...ux-speakup.org, William Hubbs <w.d.hubbs@...il.com>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] staging: speakup: Replace strncpy with memcpy

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

diff --git a/drivers/staging/speakup/kobjects.c b/drivers/staging/speakup/kobjects.c
index f1f90222186b..08f11cc17371 100644
--- a/drivers/staging/speakup/kobjects.c
+++ b/drivers/staging/speakup/kobjects.c
@@ -388,7 +388,7 @@ static ssize_t synth_store(struct kobject *kobj, struct kobj_attribute *attr,
 	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';
@@ -519,7 +519,7 @@ static ssize_t punc_store(struct kobject *kobj, struct kobj_attribute *attr,
 		return -EINVAL;
 	}
 
-	strncpy(punc_buf, buf, x);
+	memcpy(punc_buf, buf, x);
 
 	while (x && punc_buf[x - 1] == '\n')
 		x--;
-- 
2.7.4