Re: [PATCH] i2c: core: fix debugfs UAF on adapter removal

[Andi Shyti]

Hi Vasileios,

...

> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 3ec04787a737..b894563f5a75 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1826,8 +1826,6 @@ void i2c_del_adapter(struct i2c_adapter *adap)
>  
>  	i2c_host_notify_irq_teardown(adap);
>  
> -	debugfs_remove_recursive(adap->debugfs);
> -
>  	/* wait until all references to the device are gone
>  	 *
>  	 * FIXME: This is old code and should ideally be replaced by an
> @@ -1839,6 +1837,9 @@ void i2c_del_adapter(struct i2c_adapter *adap)
>  	device_unregister(&adap->dev);
>  	wait_for_completion(&adap->dev_released);
>  
> +	/* clients use this directory as their debugfs parent */
> +	debugfs_remove_recursive(adap->debugfs);
> +

Speaking of sysfs, this can't work if a new device is created
through the new_device interface. Perhaps you can remove the
attribute first with device_remove_file(), but we need to check
whether that could lead to a double removal when the device
attributes are cleaned up during device removal.

Thanks,
Andi

>  	/* free bus id */
>  	mutex_lock(&core_lock);
>  	idr_remove(&i2c_adapter_idr, adap->nr);
> -- 
> 2.47.3
>