[PATCH 4.9 043/130] HID: corsair: fix control-transfer error handling

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <johan@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/hid/hid-corsair.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/hid/hid-corsair.c
+++ b/drivers/hid/hid-corsair.c
@@ -159,7 +159,7 @@ static enum led_brightness k90_backlight
 			      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 @@ static ssize_t k90_show_macro_mode(struc
 			      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 @@ static ssize_t k90_show_current_profile(
 			      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;