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SubjectRe: [PATCH v2] sfc: falcon: potential dereference null pointer of rx_queue->page_ring
On Fri, Dec 17, 2021 at 10:33:08PM +0800, Jiasheng Jiang wrote:
> The return value of kcalloc() needs to be checked.

Your predicate is wrong. The code that uses rx_queue->page_ring
can deal with it being NULL.
The only thing you might want to do is set rx_queue->page_ptr_mask
to 0.

Martin

> To avoid dereference of null pointer in case of the failure of alloc.
> Therefore, it might be better to change the return type of
> ef4_init_rx_recycle_ring(), ef4_init_rx_queue(), ef4_start_datapath(),
> ef4_start_all(), and return -ENOMEM when alloc fails and return 0 the
> others.
> Also, ef4_realloc_channels(), ef4_net_open(), ef4_change_mtu(),
> ef4_reset_up() and ef4_pm_thaw() should deal with the return value of
> ef4_start_all().
>
> Fixes: 5a6681e22c14 ("sfc: separate out SFC4000 ("Falcon") support into new sfc-falcon driver")
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> ---
> Changelog:
>
> v1 -> v2
>
> *Change 1. Alter the "ret" to 'rc' and cleanup the rx_queue and tx_queue
> when alloc fails.
> ---
> drivers/net/ethernet/sfc/falcon/efx.c | 56 +++++++++++++++++++++------
> drivers/net/ethernet/sfc/falcon/efx.h | 2 +-
> drivers/net/ethernet/sfc/falcon/rx.c | 18 +++++++--
> 3 files changed, 60 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/ethernet/sfc/falcon/efx.c b/drivers/net/ethernet/sfc/falcon/efx.c
> index 5e7a57b680ca..89b93ed08251 100644
> --- a/drivers/net/ethernet/sfc/falcon/efx.c
> +++ b/drivers/net/ethernet/sfc/falcon/efx.c
> @@ -201,7 +201,7 @@ static void ef4_init_napi_channel(struct ef4_channel *channel);
> static void ef4_fini_napi(struct ef4_nic *efx);
> static void ef4_fini_napi_channel(struct ef4_channel *channel);
> static void ef4_fini_struct(struct ef4_nic *efx);
> -static void ef4_start_all(struct ef4_nic *efx);
> +static int ef4_start_all(struct ef4_nic *efx);
> static void ef4_stop_all(struct ef4_nic *efx);
>
> #define EF4_ASSERT_RESET_SERIALISED(efx) \
> @@ -590,7 +590,7 @@ static int ef4_probe_channels(struct ef4_nic *efx)
> * to propagate configuration changes (mtu, checksum offload), or
> * to clear hardware error conditions
> */
> -static void ef4_start_datapath(struct ef4_nic *efx)
> +static int ef4_start_datapath(struct ef4_nic *efx)
> {
> netdev_features_t old_features = efx->net_dev->features;
> bool old_rx_scatter = efx->rx_scatter;
> @@ -598,6 +598,7 @@ static void ef4_start_datapath(struct ef4_nic *efx)
> struct ef4_rx_queue *rx_queue;
> struct ef4_channel *channel;
> size_t rx_buf_len;
> + int rc;
>
> /* Calculate the rx buffer allocation parameters required to
> * support the current MTU, including padding for header
> @@ -668,7 +669,10 @@ static void ef4_start_datapath(struct ef4_nic *efx)
> }
>
> ef4_for_each_channel_rx_queue(rx_queue, channel) {
> - ef4_init_rx_queue(rx_queue);
> + rc = ef4_init_rx_queue(rx_queue);
> + if (rc)
> + goto fail;
> +
> atomic_inc(&efx->active_queues);
> ef4_stop_eventq(channel);
> ef4_fast_push_rx_descriptors(rx_queue, false);
> @@ -680,6 +684,17 @@ static void ef4_start_datapath(struct ef4_nic *efx)
>
> if (netif_device_present(efx->net_dev))
> netif_tx_wake_all_queues(efx->net_dev);
> +
> + return 0;
> +
> +fail:
> + ef4_for_each_channel(channel, efx) {
> + ef4_for_each_channel_rx_queue(rx_queue, channel)
> + ef4_fini_rx_queue(rx_queue);
> + ef4_for_each_possible_channel_tx_queue(tx_queue, channel)
> + ef4_fini_tx_queue(tx_queue);
> + }
> + return rc;
> }
>
> static void ef4_stop_datapath(struct ef4_nic *efx)
> @@ -853,7 +868,10 @@ ef4_realloc_channels(struct ef4_nic *efx, u32 rxq_entries, u32 txq_entries)
> "unable to restart interrupts on channel reallocation\n");
> ef4_schedule_reset(efx, RESET_TYPE_DISABLE);
> } else {
> - ef4_start_all(efx);
> + rc = ef4_start_all(efx);
> + if (rc)
> + return rc;
> +
> netif_device_attach(efx->net_dev);
> }
> return rc;
> @@ -1814,8 +1832,10 @@ static int ef4_probe_all(struct ef4_nic *efx)
> * is safe to call multiple times, so long as the NIC is not disabled.
> * Requires the RTNL lock.
> */
> -static void ef4_start_all(struct ef4_nic *efx)
> +static int ef4_start_all(struct ef4_nic *efx)
> {
> + int rc;
> +
> EF4_ASSERT_RESET_SERIALISED(efx);
> BUG_ON(efx->state == STATE_DISABLED);
>
> @@ -1823,10 +1843,12 @@ static void ef4_start_all(struct ef4_nic *efx)
> * of these flags are safe to read under just the rtnl lock */
> if (efx->port_enabled || !netif_running(efx->net_dev) ||
> efx->reset_pending)
> - return;
> + return 0;
>
> ef4_start_port(efx);
> - ef4_start_datapath(efx);
> + rc = ef4_start_datapath(efx);
> + if (rc)
> + return rc;
>
> /* Start the hardware monitor if there is one */
> if (efx->type->monitor != NULL)
> @@ -1838,6 +1860,8 @@ static void ef4_start_all(struct ef4_nic *efx)
> spin_lock_bh(&efx->stats_lock);
> efx->type->update_stats(efx, NULL, NULL);
> spin_unlock_bh(&efx->stats_lock);
> +
> + return 0;
> }
>
> /* Quiesce the hardware and software data path, and regular activity
> @@ -2074,7 +2098,10 @@ int ef4_net_open(struct net_device *net_dev)
> * before the monitor starts running */
> ef4_link_status_changed(efx);
>
> - ef4_start_all(efx);
> + rc = ef4_start_all(efx);
> + if (rc)
> + return rc;
> +
> ef4_selftest_async_start(efx);
> return 0;
> }
> @@ -2140,7 +2167,10 @@ static int ef4_change_mtu(struct net_device *net_dev, int new_mtu)
> ef4_mac_reconfigure(efx);
> mutex_unlock(&efx->mac_lock);
>
> - ef4_start_all(efx);
> + rc = ef4_start_all(efx);
> + if (rc)
> + return rc;
> +
> netif_device_attach(efx->net_dev);
> return 0;
> }
> @@ -2409,7 +2439,9 @@ int ef4_reset_up(struct ef4_nic *efx, enum reset_type method, bool ok)
>
> mutex_unlock(&efx->mac_lock);
>
> - ef4_start_all(efx);
> + rc = ef4_start_all(efx);
> + if (rc)
> + return rc;
>
> return 0;
>
> @@ -3033,7 +3065,9 @@ static int ef4_pm_thaw(struct device *dev)
> efx->phy_op->reconfigure(efx);
> mutex_unlock(&efx->mac_lock);
>
> - ef4_start_all(efx);
> + rc = ef4_start_all(efx);
> + if (rc)
> + goto fail;
>
> netif_device_attach(efx->net_dev);
>
> diff --git a/drivers/net/ethernet/sfc/falcon/efx.h b/drivers/net/ethernet/sfc/falcon/efx.h
> index d3b4646545fa..483501b42667 100644
> --- a/drivers/net/ethernet/sfc/falcon/efx.h
> +++ b/drivers/net/ethernet/sfc/falcon/efx.h
> @@ -39,7 +39,7 @@ void ef4_set_default_rx_indir_table(struct ef4_nic *efx);
> void ef4_rx_config_page_split(struct ef4_nic *efx);
> int ef4_probe_rx_queue(struct ef4_rx_queue *rx_queue);
> void ef4_remove_rx_queue(struct ef4_rx_queue *rx_queue);
> -void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue);
> +int ef4_init_rx_queue(struct ef4_rx_queue *rx_queue);
> void ef4_fini_rx_queue(struct ef4_rx_queue *rx_queue);
> void ef4_fast_push_rx_descriptors(struct ef4_rx_queue *rx_queue, bool atomic);
> void ef4_rx_slow_fill(struct timer_list *t);
> diff --git a/drivers/net/ethernet/sfc/falcon/rx.c b/drivers/net/ethernet/sfc/falcon/rx.c
> index 966f13e7475d..6042219ddb2f 100644
> --- a/drivers/net/ethernet/sfc/falcon/rx.c
> +++ b/drivers/net/ethernet/sfc/falcon/rx.c
> @@ -709,8 +709,8 @@ int ef4_probe_rx_queue(struct ef4_rx_queue *rx_queue)
> return rc;
> }
>
> -static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
> - struct ef4_rx_queue *rx_queue)
> +static int ef4_init_rx_recycle_ring(struct ef4_nic *efx,
> + struct ef4_rx_queue *rx_queue)
> {
> unsigned int bufs_in_recycle_ring, page_ring_size;
>
> @@ -728,13 +728,19 @@ static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
> efx->rx_bufs_per_page);
> rx_queue->page_ring = kcalloc(page_ring_size,
> sizeof(*rx_queue->page_ring), GFP_KERNEL);
> + if (!rx_queue->page_ring)
> + return -ENOMEM;
> +
> rx_queue->page_ptr_mask = page_ring_size - 1;
> +
> + return 0;
> }
>
> -void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
> +int ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
> {
> struct ef4_nic *efx = rx_queue->efx;
> unsigned int max_fill, trigger, max_trigger;
> + int rc;
>
> netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
> "initialising RX queue %d\n", ef4_rx_queue_index(rx_queue));
> @@ -744,7 +750,9 @@ void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
> rx_queue->notified_count = 0;
> rx_queue->removed_count = 0;
> rx_queue->min_fill = -1U;
> - ef4_init_rx_recycle_ring(efx, rx_queue);
> + rc = ef4_init_rx_recycle_ring(efx, rx_queue);
> + if (rc)
> + return rc;
>
> rx_queue->page_remove = 0;
> rx_queue->page_add = rx_queue->page_ptr_mask + 1;
> @@ -770,6 +778,8 @@ void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
>
> /* Set up RX descriptor ring */
> ef4_nic_init_rx(rx_queue);
> +
> + return 0;
> }
>
> void ef4_fini_rx_queue(struct ef4_rx_queue *rx_queue)
> --
> 2.25.1

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