From: Wei Fang <[email protected]>
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.
Signed-off-by: Wei Fang <[email protected]>
Reviewed-by: Shenwei Wang <[email protected]>
---
V2 changes:
1. Remove rx_packets and rx_bytes counters.
2. Use netdev_err_once instead of netdev_err.
---
drivers/net/ethernet/freescale/fec_main.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 5528b0af82ae..644f3c963730 100644
--- 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);
--
2.25.1
On Sun, Dec 18, 2022 at 6:31 PM <[email protected]> wrote:
>
> From: Wei Fang <[email protected]>
>
> 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.
>
> Signed-off-by: Wei Fang <[email protected]>
> Reviewed-by: Shenwei Wang <[email protected]>
> ---
> V2 changes:
> 1. Remove rx_packets and rx_bytes counters.
> 2. Use netdev_err_once instead of netdev_err.
> ---
> drivers/net/ethernet/freescale/fec_main.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index 5528b0af82ae..644f3c963730 100644
> --- 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);
Looks good to me.
Reviewed-by: Alexander Duyck <[email protected]>
On Mon, 19 Dec 2022 10:27:55 +0800 [email protected] wrote:
> From: Wei Fang <[email protected]>
>
> 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.
Applied but I had to change the subject because the subject should
describe the change. Mentioning the tool which found the problem
belongs in the body of the message.
> -----Original Message-----
> From: Jakub Kicinski <[email protected]>
> Sent: 2022??12??21?? 3:36
> To: Wei Fang <[email protected]>
> Cc: [email protected]; [email protected]; [email protected];
> Clark Wang <[email protected]>; Shenwei Wang
> <[email protected]>; [email protected]; dl-linux-imx
> <[email protected]>; [email protected]; [email protected]
> Subject: Re: [PATCH V2 net] net: fec: Coverity issue: Dereference null return
> value
>
> On Mon, 19 Dec 2022 10:27:55 +0800 [email protected] wrote:
> > From: Wei Fang <[email protected]>
> >
> > 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.
>
> Applied but I had to change the subject because the subject should describe
> the change. Mentioning the tool which found the problem belongs in the body
> of the message.
Thanks for taking the time to make these changes, I'll keep these things in mind
next time.