Re: [PATCH linux-next 4/4] net/dsa: fix possible NULL pointer dereference in dsa_slave_get_iflink

[Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>]

On Tue, Apr 14, 2015 at 11:20:17PM +0800, Honggang Li wrote:
> Signed-off-by: Honggang Li <honli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  net/dsa/slave.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index 827cda56..070b599 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -59,7 +59,10 @@ static int dsa_slave_get_iflink(const struct net_device *dev)
>  {
>  	struct dsa_slave_priv *p = netdev_priv(dev);
>  
> -	return p->parent->dst->master_netdev->ifindex;
> +	if (p && p->parent && p->parent->dst && p->parent->dst->master_netdev)
> +		return p->parent->dst->master_netdev->ifindex;
> +	else
> +		return 0;
>  }
I would expect some explanation why you believe that any of those pointers
can be NULL.

Guenter
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