USB: serial: io_edgeport: add missing active-port sanity check

The driver receives the active port number from the device, but never
made sure that the port number was valid. This could lead to a
NULL-pointer dereference or memory corruption in case a device sends
data for an invalid port.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index 0582d78bdb1d6a778e6ca3eea8dd6fa89ef27c54..5737add6a2a436b440792a14112288c4c4801c02 100644 (file)
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -1725,7 +1725,8 @@ static void edge_break(struct tty_struct *tty, int break_state)
 static void process_rcvd_data(struct edgeport_serial *edge_serial,
                                unsigned char *buffer, __u16 bufferLength)
 {
-       struct device *dev = &edge_serial->serial->dev->dev;
+       struct usb_serial *serial = edge_serial->serial;
+       struct device *dev = &serial->dev->dev;
        struct usb_serial_port *port;
        struct edgeport_port *edge_port;
        __u16 lastBufferLength;
@@ -1821,9 +1822,8 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial,
 
                        /* spit this data back into the tty driver if this
                           port is open */
-                       if (rxLen) {
-                               port = edge_serial->serial->port[
-                                                       edge_serial->rxPort];
+                       if (rxLen && edge_serial->rxPort < serial->num_ports) {
+                               port = serial->port[edge_serial->rxPort];
                                edge_port = usb_get_serial_port_data(port);
                                if (edge_port && edge_port->open) {
                                        dev_dbg(dev, "%s - Sending %d bytes to TTY for port %d\n",
@@ -1833,8 +1833,8 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial,
                                                        rxLen);
                                        edge_port->port->icount.rx += rxLen;
                                }
-                               buffer += rxLen;
                        }
+                       buffer += rxLen;
                        break;
 
                case EXPECT_HDR3:       /* Expect 3rd byte of status header */
@@ -1869,6 +1869,8 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
        __u8 code = edge_serial->rxStatusCode;
 
        /* switch the port pointer to the one being currently talked about */
+       if (edge_serial->rxPort >= edge_serial->serial->num_ports)
+               return;
        port = edge_serial->serial->port[edge_serial->rxPort];
        edge_port = usb_get_serial_port_data(port);
        if (edge_port == NULL) {