Re: usb/media/em28xx: use-after-free in em28xx_dvb_fini

[Andrey Konovalov]

On Wed, Nov 8, 2017 at 5:03 PM, Gustavo A. R. Silva
<garsilva@xxxxxxxxxxxxxx> wrote:
>
> Quoting Andrey Konovalov <andreyknvl@xxxxxxxxxx>:
>
>> On Tue, Nov 7, 2017 at 10:18 PM, Gustavo A. R. Silva
>> <garsilva@xxxxxxxxxxxxxx> wrote:
>>>
>>> Hi Andrey,
>>>
>>> Could you please try this patch?
>>>
>>> Thank you
>>>
>>> Gustavo A. R. Silva
>>
>>
>> Hi Gustavo,
>>
>> Still see the crash with your patch.
>>
>> Thanks!
>>
>
> Thank you, Andrey. I will look into this further.

Since I'm able to reproduce this, I can apply a patch with debug
printk's or something similar and run the reproducer. Send me a patch
if you think it might help.

>
> --
> Gustavo A. R. Silva
>
>
>>>
>>> ---
>>>  drivers/media/usb/em28xx/em28xx-dvb.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c
>>> b/drivers/media/usb/em28xx/em28xx-dvb.c
>>> index 4a7db62..fc3fb92 100644
>>> --- a/drivers/media/usb/em28xx/em28xx-dvb.c
>>> +++ b/drivers/media/usb/em28xx/em28xx-dvb.c
>>> @@ -2073,6 +2073,9 @@ static int em28xx_dvb_fini(struct em28xx *dev)
>>>         struct em28xx_dvb *dvb;
>>>         struct i2c_client *client;
>>>
>>> +       if (!dev)
>>> +               return 0;
>>> +
>>>         if (dev->is_audio_only) {
>>>                 /* Shouldn't initialize IR for this interface */
>>>                 return 0;
>>> --
>>> 2.7.4
>>>
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