From 4eb1b01de5b9d8596d6c103efcf1a15cfc1bedf7 Mon Sep 17 00:00:00 2001
From: Hanno Zulla <kontakt@hanno.de>
Date: Tue, 18 Feb 2020 12:39:31 +0100
Subject: [PATCH] HID: hid-bigbenff: fix race condition for scheduled work during removal
Git-commit: 4eb1b01de5b9d8596d6c103efcf1a15cfc1bedf7
Patch-mainline: v5.6-rc4
References: git-fixes

It's possible that there is scheduled work left while the device is
already being removed, which can cause a kernel crash. Adding a flag
will avoid this.

Signed-off-by: Hanno Zulla <kontakt@hanno.de>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

diff --git a/drivers/hid/hid-bigbenff.c b/drivers/hid/hid-bigbenff.c
index f8c552b64a89..db6da21ade06 100644
--- a/drivers/hid/hid-bigbenff.c
+++ b/drivers/hid/hid-bigbenff.c
@@ -174,6 +174,7 @@ static __u8 pid0902_rdesc_fixed[] = {
 struct bigben_device {
 	struct hid_device *hid;
 	struct hid_report *report;
+	bool removed;
 	u8 led_state;         /* LED1 = 1 .. LED4 = 8 */
 	u8 right_motor_on;    /* right motor off/on 0/1 */
 	u8 left_motor_force;  /* left motor force 0-255 */
@@ -190,6 +191,9 @@ static void bigben_worker(struct work_struct *work)
 		struct bigben_device, worker);
 	struct hid_field *report_field = bigben->report->field[0];
 
+	if (bigben->removed)
+		return;
+
 	if (bigben->work_led) {
 		bigben->work_led = false;
 		report_field->value[0] = 0x01; /* 1 = led message */
@@ -304,6 +308,7 @@ static void bigben_remove(struct hid_device *hid)
 {
 	struct bigben_device *bigben = hid_get_drvdata(hid);
 
+	bigben->removed = true;
 	cancel_work_sync(&bigben->worker);
 	hid_hw_stop(hid);
 }
@@ -324,6 +329,7 @@ static int bigben_probe(struct hid_device *hid,
 		return -ENOMEM;
 	hid_set_drvdata(hid, bigben);
 	bigben->hid = hid;
+	bigben->removed = false;
 
 	error = hid_parse(hid);
 	if (error) {
-- 
2.16.4