HID: corsair: fix control-transfer error handling

commit 7a546af50eb78ab99840903083231eb635c8a566 upstream.

Make sure to check for short control transfers in order to avoid parsing
uninitialised buffer data and leaking it to user space.

Note that the backlight and macro-mode buffer constraints are kept as
loose as possible in order to avoid any regressions should the current
buffer sizes be larger than necessary.

Fixes: 6f78193ee9ea ("HID: corsair: Add Corsair Vengeance K90 driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hid/hid-corsair.c b/drivers/hid/hid-corsair.c
index 5971907..c0303f6 100644
--- a/drivers/hid/hid-corsair.c
+++ b/drivers/hid/hid-corsair.c
@@ -159,7 +159,7 @@
 			      USB_DIR_IN | USB_TYPE_VENDOR |
 			      USB_RECIP_DEVICE, 0, 0, data, 8,
 			      USB_CTRL_SET_TIMEOUT);
-	if (ret < 0) {
+	if (ret < 5) {
 		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
 			 ret);
 		ret = -EIO;
@@ -274,7 +274,7 @@
 			      USB_DIR_IN | USB_TYPE_VENDOR |
 			      USB_RECIP_DEVICE, 0, 0, data, 2,
 			      USB_CTRL_SET_TIMEOUT);
-	if (ret < 0) {
+	if (ret < 1) {
 		dev_warn(dev, "Failed to get K90 initial mode (error %d).\n",
 			 ret);
 		ret = -EIO;
@@ -351,7 +351,7 @@
 			      USB_DIR_IN | USB_TYPE_VENDOR |
 			      USB_RECIP_DEVICE, 0, 0, data, 8,
 			      USB_CTRL_SET_TIMEOUT);
-	if (ret < 0) {
+	if (ret < 8) {
 		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
 			 ret);
 		ret = -EIO;