[linux-dvb] PCTV200e driver: solved "NULL pointer dereference"

Michel Verbraak michel at verbraak.org
Sat Jul 14 08:23:33 CEST 2007


Juan Antonio Garcia schreef:
>
> After a bit of work I have found the reason for getting the "NULL 
> Pointer dereference" error when the PCTV200e is initialized.
>
> The reason is that in the function "pctv200e_frontend_attach" 
> "adap->fe" is NULL, and when the mt352 registration fails it continues 
> being NULL. When the mt2060 is attached, in "mt2060.c"  the following 
> line:
>
>     struct dvb_frontend *fe = ops->fe;
>
> Tries to reference the NULL pointer.
>
> I have made the following modification to "pctv200e.c":
>
> static int pctv200e_frontend_attach(struct dvb_usb_adapter *adap)
> {
>     struct dvb_frontend *fe;
>
>     if ((adap->fe = dvb_attach(mt352_attach, &pctv200e_mt352_config, 
> &adap->dev->i2c_adap)) != NULL) {
>         adap->fe->ops.tuner_ops.calc_regs = dvb_usb_tuner_calc_regs;
>         return 0;
>     } else  {
>         warn("frontend_attach failed (mt352)");
>
>         fe = kzalloc(sizeof(struct dvb_frontend), GFP_KERNEL);
>         if (fe == NULL)
>             return -EIO;
>
>         adap->fe = fe;   
>     }
>     warn("next: attaching tuner.");
>
> After this the PCTV200e registers and unregisters successfully.
> So I guess these changes help...
>
> I would like to continue helping. But I would need some directions, 
> because I don't know what to do next...
>
> And I am really interested in having the PCTV200e under Linux.
>
> Thanks,
>
> Juan
>
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Juan,

Have a look at the following page fo your patch and how to get it into 
mainline. Create a patch file and send it to this list and it should get 
incorporated ito mainline as it looks to me as a sound solution to a bug.

http://www.linuxtv.org/v4lwiki/index.php/SubmittingPatches

Regards,

Michel.
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