Forwarded: [PATCH] HID: saitek: prevent NULL pointer dereference in saitek_event()

[syzbot <syzbot+eba2b3201bd25a97cddf@syzkaller.appspotmail.com>]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: [PATCH] HID: saitek: prevent NULL pointer dereference in saitek_event()
Author: dlzhangak@isoftstone.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/drivers/hid/hid-saitek.c b/drivers/hid/hid-saitek.c
index 6fe7c087c594..7e1160a24230 100644
--- a/drivers/hid/hid-saitek.c
+++ b/drivers/hid/hid-saitek.c
@@ -151,7 +151,12 @@ static int saitek_event(struct hid_device *hdev, struct hid_field *field,
 		struct hid_usage *usage, __s32 value)
 {
 	struct saitek_sc *ssc = hid_get_drvdata(hdev);
-	struct input_dev *input = field->hidinput->input;
+	struct input_dev *input;
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput)
+		return 0;
+
+	input = field->hidinput->input;
 
 	if (usage->type == EV_KEY && value &&
 			(((ssc->quirks & SAITEK_RELEASE_MODE_RAT7) &&