Re: [patch v2] [media] rc-core: prevent divide by zero bug in s_tx_carrier()

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On Sun, Sep 09, 2012 at 11:31:42PM +0300, Dan Carpenter wrote:
> Several of the drivers use carrier as a divisor in their s_tx_carrier()
> functions.  We should do a sanity check here like we do for
> LIRC_SET_REC_CARRIER.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> v2: Ben Hutchings pointed out that my first patch was not a complete
>     fix.
> 
> diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
> index 6ad4a07..28dc0f0 100644
> --- a/drivers/media/rc/ir-lirc-codec.c
> +++ b/drivers/media/rc/ir-lirc-codec.c
> @@ -211,6 +211,9 @@ static long ir_lirc_ioctl(struct file *filep, unsigned int cmd,
>  		if (!dev->s_tx_carrier)
>  			return -EINVAL;

This should be ENOSYS.

>  
> +		if (val <= 0)
> +			return -EINVAL;
> +

1) val is unsigned so it would never be less than zero.

2) A value of zero means disabling carrier modulation, which is used by 
   the mceusb driver.

So the check belongs in the individual drivers, as in the original patch.


Sean
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