netdev - Re: [PATCH net] ibmvnic fix NULL tx_pools and rx_tools issue at do

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Date:   Tue, 25 Aug 2020 08:45:55 -0500
From:   Brian W Hart <hartb@...ux.vnet.ibm.com>
To:     Dany Madden <drt@...ux.ibm.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        Mingming Cao <mmc@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH net] ibmvnic fix NULL tx_pools and rx_tools issue at
 do_reset

On Mon, Aug 24, 2020 at 07:49:23PM -0400, Dany Madden wrote:
> From: Mingming Cao <mmc@...ux.vnet.ibm.com>
> 
> At the time of do_reset, ibmvnic tries to re-initalize the tx_pools
> and rx_pools to avoid re-allocating the long term buffer. However
> there is a window inside do_reset that the tx_pools and
> rx_pools were freed before re-initialized making it possible to deference
> null pointers.
> 
> This patch fixes this issue by checking that the tx_pool
> and rx_pool are not NULL after ibmvnic_login. If so, re-allocating
> the pools. This will avoid getting into calling reset_tx/rx_pools with
> NULL adapter tx_pools/rx_pools pointer. Also add null pointer check in
> reset_tx_pools and reset_rx_pools to safe handle NULL pointer case.
> 
> Signed-off-by: Mingming Cao <mmc@...ux.vnet.ibm.com>
> Signed-off-by: Dany Madden <drt@...ux.ibm.com>
> ---
>  drivers/net/ethernet/ibm/ibmvnic.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> index 5afb3c9c52d2..5ff48e55308b 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -479,6 +479,9 @@ static int reset_rx_pools(struct ibmvnic_adapter *adapter)
>  	int i, j, rc;
>  	u64 *size_array;
> 
> +	if (!adapter->tx_pool)
> +		return -1;
> +

Should this one be testing rx_pool?

brian

>  	size_array = (u64 *)((u8 *)(adapter->login_rsp_buf) +
>  		be32_to_cpu(adapter->login_rsp_buf->off_rxadd_buff_size));
> 
> @@ -649,6 +652,9 @@ static int reset_tx_pools(struct ibmvnic_adapter *adapter)
>  	int tx_scrqs;
>  	int i, rc;
> 
> +	if (!adapter->tx_pool)
> +		return -1;
> +
>  	tx_scrqs = be32_to_cpu(adapter->login_rsp_buf->num_txsubm_subcrqs);
>  	for (i = 0; i < tx_scrqs; i++) {
>  		rc = reset_one_tx_pool(adapter, &adapter->tso_pool[i]);
> @@ -2011,7 +2017,10 @@ static int do_reset(struct ibmvnic_adapter *adapter,
>  		    adapter->req_rx_add_entries_per_subcrq !=
>  		    old_num_rx_slots ||
>  		    adapter->req_tx_entries_per_subcrq !=
> -		    old_num_tx_slots) {
> +		    old_num_tx_slots ||
> +			!adapter->rx_pool ||
> +			!adapter->tso_pool ||
> +			!adapter->tx_pool) {
>  			release_rx_pools(adapter);
>  			release_tx_pools(adapter);
>  			release_napi(adapter);
> @@ -2024,10 +2033,14 @@ static int do_reset(struct ibmvnic_adapter *adapter,
>  		} else {
>  			rc = reset_tx_pools(adapter);
>  			if (rc)
> +				netdev_dbg(adapter->netdev, "reset tx pools failed (%d)\n",
> +						rc);
>  				goto out;
> 
>  			rc = reset_rx_pools(adapter);
>  			if (rc)
> +				netdev_dbg(adapter->netdev, "reset rx pools failed (%d)\n",
> +						rc);
>  				goto out;
>  		}
>  		ibmvnic_disable_irqs(adapter);
> -- 
> 2.18.2
>