isdn/i4l: fix buffer overflow

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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index 89b09c5..38a5bb7 100644 (file)
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1376,6 +1376,7 @@ 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 (file)
--- 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)))