staging: comedi: don't dereference user memory for INSN_INTTRIG

commit 5d06e3df upstream.

`parse_insn()` is dereferencing the user-space pointer `insn->data`
directly when handling the `INSN_INTTRIG` comedi instruction.  It
shouldn't be using `insn->data` at all; it should be using the separate
`data` pointer passed to the function.  Fix it.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

drivers/staging/comedi/comedi_fops.c

@@ -809,7 +809,7 @@ static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
 				ret = -EAGAIN;
 				break;
 			}
-			ret = s->async->inttrig(dev, s, insn->data[0]);
+			ret = s->async->inttrig(dev, s, data[0]);
 			if (ret >= 0)
 				ret = 1;
 			break;