net: fec: check the return value of build_skb()

The build_skb might return a null pointer but there is no check on the
return value in the fec_enet_rx_queue(). So a null pointer dereference
might occur. To avoid this, we check the return value of build_skb. If
the return value is a null pointer, the driver will recycle the page and
update the statistic of ndev. Then jump to rx_processing_done to clear
the status flags of the BD so that the hardware can recycle the BD.

Fixes: 95698ff6177b ("net: fec: using page pool to manage RX buffers")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Shenwei Wang <Shenwei.wang@nxp.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://lore.kernel.org/r/20221219022755.1047573-1-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 5528b0af82ae984e83296ffe93e72cac917ef7fd..644f3c96373029af02ea9c8cec801c04e2329228 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1674,6 +1674,14 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
                 * bridging applications.
                 */
                skb = build_skb(page_address(page), PAGE_SIZE);
+               if (unlikely(!skb)) {
+                       page_pool_recycle_direct(rxq->page_pool, page);
+                       ndev->stats.rx_dropped++;
+
+                       netdev_err_once(ndev, "build_skb failed!\n");
+                       goto rx_processing_done;
+               }
+
                skb_reserve(skb, data_start);
                skb_put(skb, pkt_len - sub_len);
                skb_mark_for_recycle(skb);