Subject: Re: [PATCH net v3] nfp: flower: Added pointer check and continue

From: Michal Swiatkowski <[email-masked]>
Date: Fri, 18 Nov 2022 13:43:14 +0100

On Fri, Nov 18, 2022 at 11:03:17AM +0300, Denis Arefev wrote:
> Return value of a function 'kmalloc_array' is dereferenced at 
> lag_conf.c:347 without checking for null, 
> but it is usually checked for this function.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> Fixes: bb9a8d031140 ("nfp: flower: monitor and offload LAG groups")
> Signed-off-by: Denis Arefev <[email-masked]>
> ---
>  drivers/net/ethernet/netronome/nfp/flower/lag_conf.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/netronome/nfp/flower/lag_conf.c b/drivers/net/ethernet/netronome/nfp/flower/lag_conf.c
> index 63907aeb3884..1aaec4cb9f55 100644
> --- a/drivers/net/ethernet/netronome/nfp/flower/lag_conf.c
> +++ b/drivers/net/ethernet/netronome/nfp/flower/lag_conf.c
> @@ -276,7 +276,7 @@ static void nfp_fl_lag_do_work(struct work_struct *work)
>  
>  	mutex_lock(&lag->lock);
>  	list_for_each_entry_safe(entry, storage, &lag->group_list, list) {
> -		struct net_device *iter_netdev, **acti_netdevs;
> +		struct net_device *iter_netdev, **acti_netdevs = NULL;
Small nit, otherwise looks fine.

I think there is no need to set it to NULL here as it is always set to
return value from kmalloc_array().

Thanks
>  		struct nfp_flower_repr_priv *repr_priv;
>  		int active_count = 0, slaves = 0;
>  		struct nfp_repr *repr;
> @@ -308,6 +308,10 @@ static void nfp_fl_lag_do_work(struct work_struct *work)
>  
>  		acti_netdevs = kmalloc_array(entry->slave_cnt,
>  					     sizeof(*acti_netdevs), GFP_KERNEL);
> +		if (!acti_netdevs) {
> +			schedule_delayed_work(&lag->work, NFP_FL_LAG_DELAY);
> +			continue;
> +		}
>  
>  		/* Include sanity check in the loop. It may be that a bond has
>  		 * changed between processing the last notification and the
> -- 
> 2.25.1
>