[109/146] USB: cdc_acm: Fix oops when Droids MuIn LCD is connected

Greg KH
2011-06-01T08:16:14Z

From: Erik Slagter <erik@slagter.name>

commit fd5054c169d29747a44b4e1419ff47f57ae82dbc upstream.

The Droids MuIn LCD operates like a serial remote terminal.
Data received are displayed directly on the LCD. This patch
fixes the kernel null pointer oops when it is plugged in.

Add NO_DATA_INTERFACE quirk to tell the driver that "control"
and "data" interfaces are not separated for this device, which
prevents dereferencing a null pointer in the device probe code.

Signed-off-by: Erik Slagter <erik@slagter.name>
Signed-off-by: Maxin B. John <maxin.john@gmail.com>
Tested-by: Erik Slagter <erik@slagter.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/class/cdc-acm.c | 13 +++++++++++--
drivers/usb/class/cdc-acm.h | 1 +
2 files changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -946,7 +946,7 @@ static int acm_probe(struct usb_interfac
u8 ac_management_function = 0;
u8 call_management_function = 0;
int call_interface_num = -1;
- int data_interface_num;
+ int data_interface_num = -1;
unsigned long quirks;
int num_rx_buf;
int i;
@@ -1030,7 +1030,11 @@ next_desc:
if (!union_header) {
if (call_interface_num > 0) {
dev_dbg(&intf->dev, "No union descriptor, using call management descriptor\n");
- data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num));
+ /* quirks for Droids MuIn LCD */
+ if (quirks & NO_DATA_INTERFACE)
+ data_interface = usb_ifnum_to_if(usb_dev, 0);
+ else
+ data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num));
control_interface = intf;
} else {
if (intf->cur_altsetting->desc.bNumEndpoints != 3) {
@@ -1622,6 +1626,11 @@ static const struct usb_device_id acm_id
.driver_info = NOT_A_MODEM,
},

+ /* Support for Droids MuIn LCD */
+ { USB_DEVICE(0x04d8, 0x000b),
+ .driver_info = NO_DATA_INTERFACE,
+ },
+
/* control interfaces without any protocol set */
{ USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
USB_CDC_PROTO_NONE) },
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -137,3 +137,4 @@ struct acm {
#define SINGLE_RX_URB 2
#define NO_CAP_LINE 4
#define NOT_A_MODEM 8
+#define NO_DATA_INTERFACE 16