[PATCH v3] HID: hid-ntrig: fix unable to handle page fault in ntrig_report_version()

[Minjong Kim]

in ntrig_report_version(), hdev parameter passed from hid_probe().
sending descriptor to /dev/uhid can make hdev->dev.parent->parent to null
if hdev->dev.parent->parent is null, usb_dev has
invalid address(0xffffffffffffff58) that hid_to_usb_dev(hdev) returned
when usb_rcvctrlpipe() use usb_dev,it trigger
page fault error for address(0xffffffffffffff58)

add null check logic to ntrig_report_version()
before calling hid_to_usb_dev()

Signed-off-by: Minjong Kim <minbell.kim@xxxxxxxxxxx>
---
 drivers/hid/hid-ntrig.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
index 2738ce947434..0f76e241e0af 100644
--- a/drivers/hid/hid-ntrig.c
+++ b/drivers/hid/hid-ntrig.c
@@ -144,6 +144,9 @@ static void ntrig_report_version(struct hid_device *hdev)
 	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
 	unsigned char *data = kmalloc(8, GFP_KERNEL);
 
+	if (!hid_is_usb(hdev))
+		return;
+
 	if (!data)
 		goto err_free;
 
-- 
2.34.1


I checked that crashes didn't occuered this patch
then, I'm just wondering why it is effective?
could you explain me about this?

Best regards,

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