Re: [PATCH 1/6] i40e: fix problematic dereference

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 21 Apr 2016 11:42:52 +0800
Helin Zhang <helin.zhang@intel.com> wrote:

> Fix issue reported by Coverity.
> 
> Coverity ID 119267: Dereference before null check.
> 
> Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage")
> 
> Signed-off-by: Helin Zhang <helin.zhang@intel.com>
> ---
>  drivers/net/i40e/i40e_rxtx.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index 4d35d83..9c126a3 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -2592,14 +2592,14 @@ i40e_rx_queue_release_mbufs(struct i40e_rx_queue *rxq)
>  {
>  	uint16_t i;
>  
> -	/* SSE Vector driver has a different way of releasing mbufs. */
> -	if (rxq->rx_using_sse) {
> -		i40e_rx_queue_release_mbufs_vec(rxq);
> +	if (!rxq || !rxq->sw_ring) {
> +		PMD_DRV_LOG(DEBUG, "Pointer to rxq or sw_ring is NULL");
>  		return;
>  	}
>  

I can't see how you could ever trigger this.
 i40e_rx_queue_release_mbufs() is called only called from places where rxq
is guraanteed non NULL.

Are you sure Coverity isn't tell you that?