Subject: Re: [PATCH] drivers/tty/hvc: using strlcpy instead of strncpy

From: Chen Gang <[email-masked]>
Date: Thu, 28 Feb 2013 19:15:44 +0800

于 2013年02月28日 19:13, Chen Gang 写道:
> 于 2013年02月28日 18:41, Jiri Slaby 写道:
>> On 02/26/2013 04:43 AM, Chen Gang wrote:
>>>>
>>>>   when strlen pi->location_code is larger than HVCS_CLC_LENGTH + 1,
>>>>     original implementation can not let hvcsd->p_location_code NUL terminated.
>>>>   so need fix it (also can simplify the code)
>> It should never be larger because the +1 is exactly for NUL. But it is a
>> cleanup, so why not...
>>
> 
>   when strlen(&pi->location_code[0]) == HVCS_CLC_LENGTH + 2
>     then clclength will be reset to HVCS_CLC_LENGTH.
> 
>     when call strncpy, the clclength + 1 == HVCS_CLS_LENGTH + 1
>       but the '\0' of src buf is located at HVCS_CLS_LENGTH + 2.
        but the '\0' of src buf is located at HVCS_CLS_LENGTH + 3. (not + 2)

>       so no '\0' copied to dest buf.
> 
>     then the dest buf will not be ended by '\0'.
> 
>   is it correct ?
> 
>   :-)
> 
> gchen.
>  
>>>> Signed-off-by: Chen Gang <[email-masked]>
>>>> ---
>>>>  drivers/tty/hvc/hvcs.c |    9 ++-------
>>>>  1 files changed, 2 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
>>>> index 1956593..81e939e 100644
>>>> --- a/drivers/tty/hvc/hvcs.c
>>>> +++ b/drivers/tty/hvc/hvcs.c
>>>> @@ -881,17 +881,12 @@ static struct vio_driver hvcs_vio_driver = {
>>>>  /* Only called from hvcs_get_pi please */
>>>>  static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
>>>>  {
>>>> -	int clclength;
>>>> -
>>>>  	hvcsd->p_unit_address = pi->unit_address;
>>>>  	hvcsd->p_partition_ID  = pi->partition_ID;
>>>> -	clclength = strlen(&pi->location_code[0]);
>>>> -	if (clclength > HVCS_CLC_LENGTH)
>>>> -		clclength = HVCS_CLC_LENGTH;
>>>>  
>>>>  	/* copy the null-term char too */
>>>> -	strncpy(&hvcsd->p_location_code[0],
>>>> -			&pi->location_code[0], clclength + 1);
>>>> +	strlcpy(&hvcsd->p_location_code[0],
>>>> +			&pi->location_code[0], sizeof(hvcsd->p_location_code));
>>>>  }
>>>>  
>>>>  /*
>>>>
> 
> 

-- 
Chen Gang

Asianux Corporation