[PATCH] Input: evdev - Call input_flush_device() on release(), not flush()

[PATCH] Input: evdev - Call input_flush_device() on release(), not flush()

[Brendan Shanks]

input_flush_device() should only be called once the struct file is being
released and no open descriptors remain, but evdev_flush() was calling
it whenever a file descriptor was closed.

This caused uploaded force-feedback effects to be erased when a process
did a dup()/close() on the event FD, called system(), etc.

Call input_flush_device() from evdev_release() instead.

Reported-by: Mathieu Maret <mathieu.maret@gmail.com>
Signed-off-by: Brendan Shanks <bshanks@codeweavers.com>
---
 drivers/input/evdev.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index cb6e3a5f509c..3c006b265729 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -326,20 +326,6 @@ static int evdev_fasync(int fd, struct file *file, int on)
 	return fasync_helper(fd, file, on, &client->fasync);
 }
 
-static int evdev_flush(struct file *file, fl_owner_t id)
-{
-	struct evdev_client *client = file->private_data;
-	struct evdev *evdev = client->evdev;
-
-	mutex_lock(&evdev->mutex);
-
-	if (evdev->exist && !client->revoked)
-		input_flush_device(&evdev->handle, file);
-
-	mutex_unlock(&evdev->mutex);
-	return 0;
-}
-
 static void evdev_free(struct device *dev)
 {
 	struct evdev *evdev = container_of(dev, struct evdev, dev);
@@ -453,6 +439,9 @@ static int evdev_release(struct inode *inode, struct file *file)
 	unsigned int i;
 
 	mutex_lock(&evdev->mutex);
+	if (evdev->exist && !client->revoked)
+		input_flush_device(&evdev->handle, file);
+
 	evdev_ungrab(evdev, client);
 	mutex_unlock(&evdev->mutex);
 
@@ -1310,7 +1299,6 @@ static const struct file_operations evdev_fops = {
 	.compat_ioctl	= evdev_ioctl_compat,
 #endif
 	.fasync		= evdev_fasync,
-	.flush		= evdev_flush,
 	.llseek		= no_llseek,
 };
 
-- 
2.25.3

Re: [PATCH] Input: evdev - Call input_flush_device() on release(), not flush()

[Dmitry Torokhov]

On Tue, Apr 21, 2020 at 04:10:03PM -0700, Brendan Shanks wrote:
> input_flush_device() should only be called once the struct file is being
> released and no open descriptors remain, but evdev_flush() was calling
> it whenever a file descriptor was closed.
> 
> This caused uploaded force-feedback effects to be erased when a process
> did a dup()/close() on the event FD, called system(), etc.
> 
> Call input_flush_device() from evdev_release() instead.
> 
> Reported-by: Mathieu Maret <mathieu.maret@gmail.com>
> Signed-off-by: Brendan Shanks <bshanks@codeweavers.com>

Applied, thank you.

> ---
>  drivers/input/evdev.c | 18 +++---------------
>  1 file changed, 3 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index cb6e3a5f509c..3c006b265729 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -326,20 +326,6 @@ static int evdev_fasync(int fd, struct file *file, int on)
>  	return fasync_helper(fd, file, on, &client->fasync);
>  }
>  
> -static int evdev_flush(struct file *file, fl_owner_t id)
> -{
> -	struct evdev_client *client = file->private_data;
> -	struct evdev *evdev = client->evdev;
> -
> -	mutex_lock(&evdev->mutex);
> -
> -	if (evdev->exist && !client->revoked)
> -		input_flush_device(&evdev->handle, file);
> -
> -	mutex_unlock(&evdev->mutex);
> -	return 0;
> -}
> -
>  static void evdev_free(struct device *dev)
>  {
>  	struct evdev *evdev = container_of(dev, struct evdev, dev);
> @@ -453,6 +439,9 @@ static int evdev_release(struct inode *inode, struct file *file)
>  	unsigned int i;
>  
>  	mutex_lock(&evdev->mutex);
> +	if (evdev->exist && !client->revoked)
> +		input_flush_device(&evdev->handle, file);
> +
>  	evdev_ungrab(evdev, client);
>  	mutex_unlock(&evdev->mutex);
>  
> @@ -1310,7 +1299,6 @@ static const struct file_operations evdev_fops = {
>  	.compat_ioctl	= evdev_ioctl_compat,
>  #endif
>  	.fasync		= evdev_fasync,
> -	.flush		= evdev_flush,
>  	.llseek		= no_llseek,
>  };
>  
> -- 
> 2.25.3
> 

-- 
Dmitry