From: Annie Cherkaev <annie.cherk@gmail.com>
Date: Sat, 15 Jul 2017 21:08:58 +0000 (-0600)
Subject: isdn/i4l: fix buffer overflow
X-Git-Tag: v4.9.41~76
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7b3a66739ff01fcd9b8007a18ddd29edd2cb74f7;p=platform%2Fkernel%2Flinux-amlogic.git

isdn/i4l: fix buffer overflow

commit 9f5af546e6acc30f075828cb58c7f09665033967 upstream.

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 ]

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index 9b856e1..e4c43a1 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1379,6 +1379,7 @@ isdn_ioctl(struct file *file, uint cmd, ulong arg)
 			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);
diff --git a/drivers/isdn/i4l/isdn_net.c b/drivers/isdn/i4l/isdn_net.c
index c151c6d..f63a110 100644
--- a/drivers/isdn/i4l/isdn_net.c
+++ b/drivers/isdn/i4l/isdn_net.c
@@ -2611,10 +2611,9 @@ isdn_net_newslave(char *parm)
 	char newname[10];
 
 	if (p) {
-		/* Slave-Name MUST not be empty */
-		if (!strlen(p + 1))
+		/* Slave-Name MUST not be empty or overflow 'newname' */
+		if (strscpy(newname, p + 1, sizeof(newname)) <= 0)
 			return NULL;
-		strcpy(newname, p + 1);
 		*p = 0;
 		/* Master must already exist */
 		if (!(n = isdn_net_findif(parm)))