linux-kernel - [PATCH] TTY: isdn: Replace strncpy with memcpy

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Message-Id: <1530478658-23070-1-git-send-email-linux@roeck-us.net>
Date:   Sun,  1 Jul 2018 13:57:38 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Karsten Keil <isdn@...ux-pingi.de>
Cc:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] TTY: isdn: Replace strncpy with memcpy

gcc 8.1.0 complains:

drivers/isdn/i4l/isdn_tty.c: In function 'isdn_tty_suspend.isra.1':
drivers/isdn/i4l/isdn_tty.c:790:3: warning:
	'strncpy' output truncated before terminating nul copying
	as many bytes from a string as its length
drivers/isdn/i4l/isdn_tty.c:778:6: note: length computed here

drivers/isdn/i4l/isdn_tty.c: In function 'isdn_tty_resume':
drivers/isdn/i4l/isdn_tty.c:880:3: warning:
	'strncpy' output truncated before terminating nul copying
	as many bytes from a string as its length
drivers/isdn/i4l/isdn_tty.c:817:6: 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/isdn/i4l/isdn_tty.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/isdn/i4l/isdn_tty.c b/drivers/isdn/i4l/isdn_tty.c
index 960f26348bb5..b730037a0e2d 100644
--- a/drivers/isdn/i4l/isdn_tty.c
+++ b/drivers/isdn/i4l/isdn_tty.c
@@ -787,7 +787,7 @@ isdn_tty_suspend(char *id, modem_info *info, atemu *m)
 		cmd.parm.cmsg.para[3] = 4; /* 16 bit 0x0004 Suspend */
 		cmd.parm.cmsg.para[4] = 0;
 		cmd.parm.cmsg.para[5] = l;
-		strncpy(&cmd.parm.cmsg.para[6], id, l);
+		memcpy(&cmd.parm.cmsg.para[6], id, l);
 		cmd.command = CAPI_PUT_MESSAGE;
 		cmd.driver = info->isdn_driver;
 		cmd.arg = info->isdn_channel;
@@ -877,7 +877,7 @@ isdn_tty_resume(char *id, modem_info *info, atemu *m)
 		cmd.parm.cmsg.para[3] = 5; /* 16 bit 0x0005 Resume */
 		cmd.parm.cmsg.para[4] = 0;
 		cmd.parm.cmsg.para[5] = l;
-		strncpy(&cmd.parm.cmsg.para[6], id, l);
+		memcpy(&cmd.parm.cmsg.para[6], id, l);
 		cmd.command = CAPI_PUT_MESSAGE;
 		info->dialing = 1;
 //		strcpy(dev->num[i], n);
-- 
2.7.4