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

From: Chen Gang <[email-masked]>
Date: Thu, 28 Feb 2013 19:13:09 +0800

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.
      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