tty: mxser: fix usage of opmode_ioaddr

mxser_port->opmode_ioaddr is initialized only for MOXA_MUST_MU860_HWID
chips, but no precautions have been undertaken to prevent reading and
writing to undefined port number.

Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 71d6eb2c93b1..f97b196693c6 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -1618,8 +1618,12 @@ static int mxser_ioctl_special(unsigned int cmd, void __user *argp)
                                 if (ip->type == PORT_16550A)
                                         me->fifo[p] = 1;
 
-                                opmode = inb(ip->opmode_ioaddr)>>((p % 4) * 2);
-                                opmode &= OP_MODE_MASK;
+                                if (ip->board->chip_flag == MOXA_MUST_MU860_HWID) {
+                                        opmode = inb(ip->opmode_ioaddr)>>((p % 4) * 2);
+                                        opmode &= OP_MODE_MASK;
+                                } else {
+                                        opmode = RS232_MODE;
+                                }
                                 me->iftype[p] = opmode;
                                 mutex_unlock(&port->mutex);
                         }
@@ -1670,6 +1674,9 @@ static int mxser_ioctl(struct tty_struct *tty,
                 return mxser_ioctl_special(cmd, argp);
 
         if (cmd == MOXA_SET_OP_MODE || cmd == MOXA_GET_OP_MODE) {
+                if (info->board->chip_flag != MOXA_MUST_MU860_HWID)
+                        return -EFAULT;
+
                 int p;
                 unsigned long opmode;
                 static unsigned char ModeMask[] = { 0xfc, 0xf3, 0xcf, 0x3f };