[38/55] USB: Fix bad dma problem on WDM device disconnect

[Greg KH]

2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Robert Lukassen <Robert.Lukassen@xxxxxxxxxx>

commit 878b753e32ca765cd346a5d3038d630178ec78ff upstream.

In the WDM class driver a disconnect event leads to calls to
usb_free_coherent to put back two USB DMA buffers allocated earlier.
The call to usb_free_coherent uses a different size parameter
(desc->wMaxCommand) than the corresponding call to usb_alloc_coherent
(desc->bMaxPacketSize0).

When a disconnect event occurs, this leads to 'bad dma' complaints
from usb core because the USB DMA buffer is being pushed back to the
'buffer-2048' pool from which it has not been allocated.

This patch against the most recent linux-2.6 kernel ensures that the
parameters used by usb_alloc_coherent & usb_free_coherent calls in
cdc-wdm.c match.

Signed-off-by: Robert Lukassen <robert.lukassen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/usb/class/cdc-wdm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -281,7 +281,7 @@ static void cleanup(struct wdm_device *d
 			  desc->sbuf,
 			  desc->validity->transfer_dma);
 	usb_free_coherent(interface_to_usbdev(desc->intf),
-			  desc->wMaxCommand,
+			  desc->bMaxPacketSize0,
 			  desc->inbuf,
 			  desc->response->transfer_dma);
 	kfree(desc->orq);


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