From 9f5af546e6acc30f075828cb58c7f09665033967 Mon Sep 17 00:00:00 2001
From: Annie Cherkaev <annie.cherk@gmail.com>
Date: Sat, 15 Jul 2017 15:08:58 -0600
Subject: [PATCH] isdn/i4l: fix buffer overflow
Git-commit: 9f5af546e6acc30f075828cb58c7f09665033967
Patch-mainline: 4.13-rc4
References: CVE-2017-12762 bsc#1053148

This fixes a potential buffer overflow in isdn_net.c caused by an
unbounded strcpy.

[ ISDN seems to be effectively unmaintained, and the I4L driver in
  particular is long deprecated, but in case somebody uses this..
    - Linus ]

[ rewrote the code using strlcpy() instead of strscpy() that isn't yet
  present in older SLE kernels -- tiwai ]

Signed-off-by: Jiten Thakkar <jitenmt@gmail.com>
Signed-off-by: Annie Cherkaev <annie.cherk@gmail.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/isdn/i4l/isdn_common.c |    1 +
 drivers/isdn/i4l/isdn_net.c    |    2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1380,6 +1380,7 @@ isdn_ioctl(struct file *file, uint cmd,
 				if (arg) {
 					if (copy_from_user(bname, argp, sizeof(bname) - 1))
 						return -EFAULT;
+					bname[sizeof(bname)-1] = 0;
 				} else
 					return -EINVAL;
 				ret = mutex_lock_interruptible(&dev->mtx);
--- a/drivers/isdn/i4l/isdn_net.c
+++ b/drivers/isdn/i4l/isdn_net.c
@@ -2645,7 +2645,7 @@ isdn_net_newslave(char *parm)
 		/* Slave-Name MUST not be empty */
 		if (!strlen(p + 1))
 			return NULL;
-		strcpy(newname, p + 1);
+		strlcpy(newname, p + 1, sizeof(newname));
 		*p = 0;
 		/* Master must already exist */
 		if (!(n = isdn_net_findif(parm)))
