Use spinlocks to deal with workers introducing a wrapper
bigben_schedule_work(), and several spinlock checks.
Otherwise, bigben_set_led() may schedule bigben->worker after the
structure has been freed, causing a use-after-free.
Fixes: 4eb1b01de5b9 ("HID: hid-bigbenff: fix race condition for scheduled work during removal")
Signed-off-by: Pietro Borrello <borrello@xxxxxxxxxxxxxxxx>
---
drivers/hid/hid-bigbenff.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)
diff --git a/drivers/hid/hid-bigbenff.c b/drivers/hid/hid-bigbenff.c
index e8b16665860d..28769aa7fed6 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;
+ spinlock_t lock;
bool removed;
u8 led_state; /* LED1 = 1 .. LED4 = 8 */
u8 right_motor_on; /* right motor off/on 0/1 */
@@ -184,15 +185,24 @@ struct bigben_device {
struct work_struct worker;
};
+static inline void bigben_schedule_work(struct bigben_device *bigben)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&bigben->lock, flags);
+ if (!bigben->removed)
+ schedule_work(&bigben->worker);
+ spin_unlock_irqrestore(&bigben->lock, flags);
+}
static void bigben_worker(struct work_struct *work)
{
struct bigben_device *bigben = container_of(work,
struct bigben_device, worker);
struct hid_field *report_field = bigben->report->field[0];
+ unsigned long flags;
- if (bigben->removed || !report_field)
- return;
+ spin_lock_irqsave(&bigben->lock, flags);
if (bigben->work_led) {
bigben->work_led = false;
@@ -219,6 +229,8 @@ static void bigben_worker(struct work_struct *work)
report_field->value[7] = 0x00; /* padding */
hid_hw_request(bigben->hid, bigben->report, HID_REQ_SET_REPORT);
}
+
+ spin_unlock_irqrestore(&bigben->lock, flags);
}
static int hid_bigben_play_effect(struct input_dev *dev, void *data,
@@ -228,6 +240,7 @@ static int hid_bigben_play_effect(struct input_dev *dev, void *data,
struct bigben_device *bigben = hid_get_drvdata(hid);
u8 right_motor_on;
u8 left_motor_force;
+ unsigned long flags;
if (!bigben) {
hid_err(hid, "no device data\n");
@@ -242,10 +255,13 @@ static int hid_bigben_play_effect(struct input_dev *dev, void *data,
if (right_motor_on != bigben->right_motor_on ||
left_motor_force != bigben->left_motor_force) {
+ spin_lock_irqsave(&bigben->lock, flags);
bigben->right_motor_on = right_motor_on;
bigben->left_motor_force = left_motor_force;
bigben->work_ff = true;
- schedule_work(&bigben->worker);
+ spin_unlock_irqrestore(&bigben->lock, flags);
+
+ bigben_schedule_work(bigben);
}
return 0;
@@ -259,6 +275,7 @@ static void bigben_set_led(struct led_classdev *led,
struct bigben_device *bigben = hid_get_drvdata(hid);
int n;
bool work;
+ unsigned long flags;
if (!bigben) {
hid_err(hid, "no device data\n");
@@ -267,6 +284,7 @@ static void bigben_set_led(struct led_classdev *led,
for (n = 0; n < NUM_LEDS; n++) {
if (led == bigben->leds[n]) {
+ spin_lock_irqsave(&bigben->lock, flags);
if (value == LED_OFF) {
work = (bigben->led_state & BIT(n));
bigben->led_state &= ~BIT(n);
@@ -274,10 +292,11 @@ static void bigben_set_led(struct led_classdev *led,
work = !(bigben->led_state & BIT(n));
bigben->led_state |= BIT(n);
}
+ spin_unlock_irqrestore(&bigben->lock, flags);
if (work) {
bigben->work_led = true;
- schedule_work(&bigben->worker);
+ bigben_schedule_work(bigben);
}
return;
}
@@ -307,8 +326,12 @@ static enum led_brightness bigben_get_led(struct led_classdev *led)
static void bigben_remove(struct hid_device *hid)
{
struct bigben_device *bigben = hid_get_drvdata(hid);
+ unsigned long flags;
+ spin_lock_irqsave(&bigben->lock, flags);
bigben->removed = true;
+ spin_unlock_irqrestore(&bigben->lock, flags);
+
cancel_work_sync(&bigben->worker);
hid_hw_stop(hid);
}
@@ -362,6 +385,7 @@ static int bigben_probe(struct hid_device *hid,
set_bit(FF_RUMBLE, hidinput->input->ffbit);
INIT_WORK(&bigben->worker, bigben_worker);
+ spin_lock_init(&bigben->lock);
error = input_ff_create_memless(hidinput->input, NULL,
hid_bigben_play_effect);
@@ -402,7 +426,7 @@ static int bigben_probe(struct hid_device *hid,
bigben->left_motor_force = 0;
bigben->work_led = true;
bigben->work_ff = true;
- schedule_work(&bigben->worker);
+ bigben_schedule_work(bigben);
hid_info(hid, "LED and force feedback support for BigBen gamepad\n");
--
2.25.1
