USB: mos7840: fix tiocmget error handling

Make sure to return errors from tiocmget rather than rely on
uninitialised stack data.

Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index fdf953539c62..e5bdd987b9e8 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1532,7 +1532,11 @@ static int mos7840_tiocmget(struct tty_struct *tty)
                 return -ENODEV;
 
         status = mos7840_get_uart_reg(port, MODEM_STATUS_REGISTER, &msr);
+        if (status != 1)
+                return -EIO;
         status = mos7840_get_uart_reg(port, MODEM_CONTROL_REGISTER, &mcr);
+        if (status != 1)
+                return -EIO;
         result = ((mcr & MCR_DTR) ? TIOCM_DTR : 0)
             | ((mcr & MCR_RTS) ? TIOCM_RTS : 0)
             | ((mcr & MCR_LOOPBACK) ? TIOCM_LOOP : 0)