[PATCH] TTY: isdn: Replace strncpy with memcpy

[PATCH] TTY: isdn: Replace strncpy with memcpy

[Guenter Roeck]

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@roeck-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

Re: [PATCH] TTY: isdn: Replace strncpy with memcpy

[David Miller]

From: Guenter Roeck <linux@roeck-us.net>
Date: Sun,  1 Jul 2018 13:57:38 -0700

> 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@roeck-us.net>

Applied.