USB: serial: oti6858: fix NULL-deref at open

commit 5afeef2366db14587b65558bbfd5a067542e07fb upstream.

Fix NULL-pointer dereference in open() should the device lack the
expected endpoints:

Unable to handle kernel NULL pointer dereference at virtual address 00000030
...
PC is at oti6858_open+0x30/0x1d0 [oti6858]

Note that a missing interrupt-in endpoint would have caused open() to
fail.

Fixes: 49cdee0ed0fc ("USB: oti6858 usb-serial driver (in Nokia CA-42
cable)")
Signed-off-by: Johan Hovold <johan@kernel.org>
[bwh: Backported to 3.2: add this check to the existing
 usb_serial_driver::attach implementation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/oti6858.c b/drivers/usb/serial/oti6858.c
index 8ceaa89..dffbe61 100644 (file)
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -347,9 +347,17 @@ static void send_data(struct work_struct *work)
 static int oti6858_startup(struct usb_serial *serial)
 {
        struct usb_serial_port *port = serial->port[0];
+       unsigned char num_ports = serial->num_ports;
        struct oti6858_private *priv;
        int i;
 
+       if (serial->num_bulk_in < num_ports ||
+                       serial->num_bulk_out < num_ports ||
+                       serial->num_interrupt_in < num_ports) {
+               dev_err(&serial->interface->dev, "missing endpoints\n");
+               return -ENODEV;
+       }
+
        for (i = 0; i < serial->num_ports; ++i) {
                priv = kzalloc(sizeof(struct oti6858_private), GFP_KERNEL);
                if (!priv)