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Message-ID: <4d0652cd-e3ca-4319-b012-142a110efe15@gmail.com>
Date:   Thu, 7 Apr 2022 09:55:23 +0800
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Subject: Re: [PATCH] usb: misc: fix improper handling of refcount in
 uss720_probe()
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To:     Oliver Neukum <oneukum@suse.com>, gregkh@linuxfoundation.org,
        mudongliangabcd@gmail.com
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220406073349.22203-1-hbh25y@gmail.com>
 <f90522c4-f7d6-3068-9789-8c6d893f2768@suse.com>
From:   Hangyu Hua <hbh25y@gmail.com>
In-Reply-To: <f90522c4-f7d6-3068-9789-8c6d893f2768@suse.com>
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Oh, i sorry. Thank you for your reminder. I will remake a patch carefully.

On 2022/4/6 19:47, Oliver Neukum wrote:
> 
> 
> On 06.04.22 09:33, Hangyu Hua wrote:
>> usb_put_dev shouldn't be called when uss720_probe succeeds because of
>> priv->usbdev. At the same time, priv->usbdev shouldn't be set to NULL
>> before destroy_priv in uss720_disconnect because usb_put_dev is in
>> destroy_priv.
> 
> Hi,
> 
> I am sorry, but that's a clear NACK.
>> @@ -754,13 +753,13 @@ static void uss720_disconnect(struct usb_interface *intf)
>>   	usb_set_intfdata(intf, NULL);
>>   	if (pp) {
>>   		priv = pp->private_data;
>> -		priv->usbdev = NULL;
>>   		priv->pp = NULL;
>>   		dev_dbg(&intf->dev, "parport_remove_port\n");
>>   		parport_remove_port(pp);
>>   		parport_put_port(pp);
>>   		kill_all_async_requests_priv(priv);
>>   		kref_put(&priv->ref_count, destroy_priv);
>> +		priv->usbdev = NULL;
> 
> That is a clear use after free The patch is no good in this state..
> 
>      HTH
>          Oliver
>