Input: uinput - take event lock when submitting FF request "event"

To avoid racing with FF playback events and corrupting device's event
queue take event_lock spinlock when calling uinput_dev_event() when
submitting a FF upload or erase "event".

Tested-by: Mikhail Gavrilov <[email protected]>
Link: https://patch.msgid.link/[email protected]
Cc: [email protected]
Signed-off-by: Dmitry Torokhov <[email protected]>

Author: dtor

drivers/input/misc/uinput.c

@@ -25,8 +25,10 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/fs.h>
+#include <linux/lockdep.h>
 #include <linux/miscdevice.h>
 #include <linux/overflow.h>
+#include <linux/spinlock.h>
 #include <linux/input/mt.h>
 #include "../input-compat.h"
 
@@ -76,6 +78,8 @@ static int uinput_dev_event(struct input_dev *dev,
 	struct uinput_device	*udev = input_get_drvdata(dev);
 	struct timespec64	ts;
 
+	lockdep_assert_held(&dev->event_lock);
+
 	ktime_get_ts64(&ts);
 
 	udev->buff[udev->head] = (struct input_event) {
@@ -147,6 +151,7 @@ static void uinput_request_release_slot(struct uinput_device *udev,
 static int uinput_request_send(struct uinput_device *udev,
 			       struct uinput_request *request)
 {
+	unsigned long flags;
 	int retval = 0;
 
 	spin_lock(&udev->state_lock);
@@ -160,7 +165,9 @@ static int uinput_request_send(struct uinput_device *udev,
 	 * Tell our userspace application about this new request
 	 * by queueing an input event.
 	 */
+	spin_lock_irqsave(&udev->dev->event_lock, flags);
 	uinput_dev_event(udev->dev, EV_UINPUT, request->code, request->id);
+	spin_unlock_irqrestore(&udev->dev->event_lock, flags);
 
  out:
 	spin_unlock(&udev->state_lock);