Re: [PATCH 2/4] HID: logitech-hidpp: check name retrieval return code

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

On Dec 11 2014 or thereabouts, Peter Wu wrote:
> hidpp_devicenametype_get_device_name() may return a negative value on
> protocol errors (for example, when the device is powered off).
> Explicitly check this condition to avoid a long-running loop.
> 
> (0 cannot be returned as __name_length - index > 0, but check for it
> anyway as it would otherwise result in an infinite loop.)
> 
> Signed-off-by: Peter Wu <peter@lekensteyn.nl>
> ---

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Cheers,
Benjamin

>  drivers/hid/hid-logitech-hidpp.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> index 5066df8..4d72c20 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -484,10 +484,16 @@ static char *hidpp_get_device_name(struct hidpp_device *hidpp)
>  	if (!name)
>  		return NULL;
>  
> -	while (index < __name_length)
> -		index += hidpp_devicenametype_get_device_name(hidpp,
> +	while (index < __name_length) {
> +		ret = hidpp_devicenametype_get_device_name(hidpp,
>  			feature_index, index, name + index,
>  			__name_length - index);
> +		if (ret <= 0) {
> +			kfree(name);
> +			return NULL;
> +		}
> +		index += ret;
> +	}
>  
>  	return name;
>  }
> -- 
> 2.1.3
>