[PATCH v2] gpu: drm: drm_dp_mst_topology.c: Fix improper use of strncat

[Jani Nikula]

On Sun, 12 Oct 2014, Rickard Strandqvist <rickard_strandqvist at spectrumdigital.se> wrote:
> Fixed wrong usage of strncat, switched to strlcpy.
> While sending the string size to function to reduce
> the potential for misuse in future.
>
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist at spectrumdigital.se>

Reviewed-by: Jani Nikula <jani.nikula at intel.com>

> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c |   15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index ac3c273..2a146d1 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -995,19 +995,20 @@ static void drm_dp_check_port_guid(struct drm_dp_mst_branch *mstb,
>  
>  static void build_mst_prop_path(struct drm_dp_mst_port *port,
>  				struct drm_dp_mst_branch *mstb,
> -				char *proppath)
> +				char *proppath,
> +				size_t proppath_size)
>  {
>  	int i;
>  	char temp[8];
> -	snprintf(proppath, 255, "mst:%d", mstb->mgr->conn_base_id);
> +	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
>  	for (i = 0; i < (mstb->lct - 1); i++) {
>  		int shift = (i % 2) ? 0 : 4;
>  		int port_num = mstb->rad[i / 2] >> shift;
> -		snprintf(temp, 8, "-%d", port_num);
> -		strncat(proppath, temp, 255);
> +		snprintf(temp, sizeof(temp), "-%d", port_num);
> +		strlcat(proppath, temp, proppath_size);
>  	}
> -	snprintf(temp, 8, "-%d", port->port_num);
> -	strncat(proppath, temp, 255);
> +	snprintf(temp, sizeof(temp), "-%d", port->port_num);
> +	strlcat(proppath, temp, proppath_size);
>  }
>  
>  static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
> @@ -1078,7 +1079,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
>  
>  	if (created && !port->input) {
>  		char proppath[255];
> -		build_mst_prop_path(port, mstb, proppath);
> +		build_mst_prop_path(port, mstb, proppath, sizeof(proppath));
>  		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
>  	}
>  
> -- 
> 1.7.10.4
>
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-- 
Jani Nikula, Intel Open Source Technology Center