Re: [PATCH net-next v08 8/9] hinic3: Add mac filter ops

[Jakub Kicinski <kuba@kernel.org>]

AI code review points out:

> +static int hinic3_mac_filter_sync_hw(struct net_device *netdev,
> +				     struct list_head *del_list,
> +				     struct list_head *add_list,
> +				     int *add_count)
> +{
> +	struct hinic3_mac_filter *ftmp;
> +	struct hinic3_mac_filter *f;
> +	int err;
> +
> +	if (!list_empty(del_list)) {
> +		list_for_each_entry_safe(f, ftmp, del_list, list) {
> +			/* ignore errors when deleting mac */
> +			hinic3_filter_addr_unsync(netdev, f->addr);
> +			list_del(&f->list);
> +			kfree(f);
> +		}
> +	}
> +
> +	if (!list_empty(add_list)) {
> +		list_for_each_entry_safe(f, ftmp, add_list, list) {
> +			if (f->state != HINIC3_MAC_HW_SYNCING)
> +				continue;
> +
> +			err = hinic3_filter_addr_sync(netdev, f->addr);
> +			if (err) {
> +				netdev_err(netdev, "Failed to add mac\n");
> +				return err;
> +			}
> +
> +			f->state = HINIC3_MAC_HW_SYNCED;
> +			(*add_count)++;
> +		}
> +	}
> +
> +	return 0;
> +}

[ ... ]

> +	err = hinic3_mac_filter_sync_hw(netdev, &tmp_del_list,
> +					&tmp_add_list, &add_count);
> +	if (err) {
> +		/* there were errors, delete all mac in hw */
> +		hinic3_undo_add_filter_entries(mac_filter_list, &tmp_add_list);

[ ... ]

> +		hinic3_mac_filter_sync_hw(netdev, &tmp_del_list,
> +					  &tmp_add_list, NULL);
                                                  ^^^^

Can this NULL pointer dereference add_count in hinic3_mac_filter_sync_hw()?

When hinic3_filter_addr_sync() fails in the first call to
hinic3_mac_filter_sync_hw(), the function returns early with an error.
At that point tmp_add_list may still contain entries with state
HINIC3_MAC_HW_SYNCING (entries that were not yet processed).

The second call passes NULL for add_count. If tmp_add_list is not empty
and has entries with HINIC3_MAC_HW_SYNCING state, the code will execute
(*add_count)++ with add_count being NULL.