kaweth: Fix memory leak in kaweth_control()

kaweth_control() never frees the buffer that it allocates for the USB
control message.  Test case:

while :; do ifconfig eth2 down ; ifconfig eth2 up ; done

This is a tiny buffer so it is a slow leak.  If you want to speed up the
process, you can change the allocation size to e.g. 16384 bytes, and it
will consume several megabytes within a few minutes.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/kaweth.c

@@ -263,6 +263,7 @@ static int kaweth_control(struct kaweth_device *kaweth,
 			  int timeout)
 {
 	struct usb_ctrlrequest *dr;
+	int retval;
 
 	dbg("kaweth_control()");
 
@@ -278,18 +279,21 @@ static int kaweth_control(struct kaweth_device *kaweth,
 		return -ENOMEM;
 	}
 
-	dr->bRequestType= requesttype;
+	dr->bRequestType = requesttype;
 	dr->bRequest = request;
 	dr->wValue = cpu_to_le16(value);
 	dr->wIndex = cpu_to_le16(index);
 	dr->wLength = cpu_to_le16(size);
 
-	return kaweth_internal_control_msg(kaweth->dev,
-					pipe,
-					dr,
-					data,
-					size,
-					timeout);
+	retval = kaweth_internal_control_msg(kaweth->dev,
+					     pipe,
+					     dr,
+					     data,
+					     size,
+					     timeout);
+
+	kfree(dr);
+	return retval;
 }
 
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