This is a note to let you know that I've just added the patch titled net: fec: check the return value of build_skb() to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-fec-check-the-return-value-of-build_skb.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit fed95932787ef720b45278709f68d2c313b70670 Author: Wei Fang <wei.fang@xxxxxxx> Date: Mon Dec 19 10:27:55 2022 +0800 net: fec: check the return value of build_skb() [ Upstream commit 19e72b064fc32cd58f6fc0b1eb64ac2e4f770e76 ] 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@xxxxxxx> Reviewed-by: Shenwei Wang <Shenwei.wang@xxxxxxx> Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx> Link: https://lore.kernel.org/r/20221219022755.1047573-1-wei.fang@xxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 23e1a94b9ce4..f250b0df27fb 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -1642,6 +1642,14 @@ 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, FEC_ENET_XDP_HEADROOM); skb_put(skb, pkt_len - 4); skb_mark_for_recycle(skb);