udldrmfb: udl_get_edid: usb_control_msg buffer must not be on the stack

The buffer passed to usb_control_msg may end up in scatter-gather list, and
may thus not be on the stack. Having it on the stack usually works on x86, but
not on other archs.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/udl/udl_connector.c

@@ -22,13 +22,17 @@
 static u8 *udl_get_edid(struct udl_device *udl)
 {
 	u8 *block;
-	char rbuf[3];
+	char *rbuf;
 	int ret, i;
 
 	block = kmalloc(EDID_LENGTH, GFP_KERNEL);
 	if (block == NULL)
 		return NULL;
 
+	rbuf = kmalloc(2, GFP_KERNEL);
+	if (rbuf == NULL)
+		goto error;
+
 	for (i = 0; i < EDID_LENGTH; i++) {
 		ret = usb_control_msg(udl->ddev->usbdev,
 				      usb_rcvctrlpipe(udl->ddev->usbdev, 0), (0x02),
@@ -42,10 +46,12 @@ static u8 *udl_get_edid(struct udl_device *udl)
 		block[i] = rbuf[1];
 	}
 
+	kfree(rbuf);
 	return block;
 
 error:
 	kfree(block);
+	kfree(rbuf);
 	return NULL;
 }