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SubjectRe: [PATCH 6/6] staging: pi433: Rename enum modShaping in rf69_enum.h
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Am 04.12.2017 um 12:33 schrieb Dan Carpenter:
> On Sun, Dec 03, 2017 at 04:17:26PM +0100, Simon Sandström wrote:
>> diff --git a/drivers/staging/pi433/pi433_if.h b/drivers/staging/pi433/pi433_if.h
>> index 34ff0d4807bd..bcfe29840889 100644
>> --- a/drivers/staging/pi433/pi433_if.h
>> +++ b/drivers/staging/pi433/pi433_if.h
>> @@ -63,7 +63,7 @@ struct pi433_tx_cfg {
>> __u16 bit_rate;
>> __u32 dev_frequency;
>> enum modulation modulation;
>> - enum modShaping modShaping;
>> + enum mod_shaping mod_shaping;
>>
>
> I looked at how mod_shaping is set and the only place is in the ioctl:
>
> 789 case PI433_IOC_WR_TX_CFG:
> 790 if (copy_from_user(&instance->tx_cfg, argp,
> 791 sizeof(struct pi433_tx_cfg)))
> 792 return -EFAULT;
> 793 break;
>
> We just write over the whole config. Including important things like
> rx_cfg.fixed_message_length. There is no locking so when we do things
> like:
>
> 385 /* fixed or unlimited length? */
> 386 if (dev->rx_cfg.fixed_message_length != 0)
> 387 {
> 388 if (dev->rx_cfg.fixed_message_length > dev->rx_buffer_size)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> check
>
> 389 {
> 390 retval = -1;
> 391 goto abort;
> 392 }
> 393 bytes_total = dev->rx_cfg.fixed_message_length;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> set this in the ioctl after the check but before this line and it looks
> like a security problem.
>
> 394 dev_dbg(dev->dev,"rx: msg len set to %d by fixed length", bytes_total);
> 395 }
>
> Anyway, I guess this patch is fine.
>
> regards,
> dan carpenter
>

Hi Dan,

you are mixing rx and tx. The part from IOCTL is copied from the
tx-part, the lower part is dealing with rx.

With rx there should be no problem, since IOCTL is blocked, as long as
an rx operation is going on.

With tx, I also expect no problems, since instance->tx_cfg is never used
to configure the rf69. Everytime, you pass in new data via write() a
copy of tx_cfg is made. Transmission is done, using the copy of the
tx_cfg, never by using instance->tx_cfg.

But maybe I didn't got your point and misunderstand your intention.

Cheers,

Marcus

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