Re: [PATCH v2] net: thunderx: nicvf_main: Fix potential NULL pointer dereferences

[Eric Dumazet]

On 04/03/2018 03:04 PM, Gustavo A. R. Silva wrote:
> Add null check on kmalloc() return value in order to prevent
> a null pointer dereference.
> 
> Addresses-Coverity-ID: 1467429 ("Dereference null return value")
> Fixes: 37c3347eb247 ("net: thunderx: add ndo_set_rx_mode callback implementation for VF")
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
> Changes in v2:
>  - Add a null check on a second kmalloc a few lines below. Thanks to
>    Eric Dumazet for pointing this out.
> 
>  drivers/net/ethernet/cavium/thunder/nicvf_main.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> index 1e9a31f..f7b5ca5 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> @@ -1999,10 +1999,14 @@ static void nicvf_set_rx_mode(struct net_device *netdev)
>  				struct xcast_addr *xaddr;
>  
>  				mc_list = kmalloc(sizeof(*mc_list), GFP_ATOMIC);
> +				if (unlikely(!mc_list))
> +					return;
>  				INIT_LIST_HEAD(&mc_list->list);
>  				netdev_hw_addr_list_for_each(ha, &netdev->mc) {
>  					xaddr = kmalloc(sizeof(*xaddr),
>  							GFP_ATOMIC);
> +					if (unlikely(!xaddr))
> +						return;

So now you leak memory :/

If you fix bugs, please do not add new ones.

>  					xaddr->addr =
>  						ether_addr_to_u64(ha->addr);
>  					list_add_tail(&xaddr->list,
>