The rtsn_start_xmit() returns NETDEV_TX_OK without freeing skb
in case of skb->len being too long, add dev_kfree_skb_any() to fix it.

Fixes: b0d3969d2b4d ("net: ethernet: rtsn: Add support for Renesas Ethernet-TSN")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
---
 drivers/net/ethernet/renesas/rtsn.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/renesas/rtsn.c b/drivers/net/ethernet/renesas/rtsn.c
index f9f63c61d792..6b3f7fca8d15 100644
--- a/drivers/net/ethernet/renesas/rtsn.c
+++ b/drivers/net/ethernet/renesas/rtsn.c
@@ -1057,6 +1057,7 @@ static netdev_tx_t rtsn_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	if (skb->len >= TX_DS) {
 		priv->stats.tx_dropped++;
 		priv->stats.tx_errors++;
+		dev_kfree_skb_any(skb);
 		goto out;
 	}
 
-- 
2.17.1

On Mon, Oct 14, 2024 at 4:43 PM Wang Hai <wanghai38@huawei.com> wrote:
>
> The rtsn_start_xmit() returns NETDEV_TX_OK without freeing skb
> in case of skb->len being too long, add dev_kfree_skb_any() to fix it.
>
> Fixes: b0d3969d2b4d ("net: ethernet: rtsn: Add support for Renesas Ethernet-TSN")
> Signed-off-by: Wang Hai <wanghai38@huawei.com>
> ---
>  drivers/net/ethernet/renesas/rtsn.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/ethernet/renesas/rtsn.c b/drivers/net/ethernet/renesas/rtsn.c
> index f9f63c61d792..6b3f7fca8d15 100644
> --- a/drivers/net/ethernet/renesas/rtsn.c
> +++ b/drivers/net/ethernet/renesas/rtsn.c
> @@ -1057,6 +1057,7 @@ static netdev_tx_t rtsn_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>         if (skb->len >= TX_DS) {
>                 priv->stats.tx_dropped++;
>                 priv->stats.tx_errors++;
> +               dev_kfree_skb_any(skb);
>                 goto out;
>         }
>

Note this is dead code for this driver. This condition should never be
hit with checks in upper layers,
because TX_DS is bigger than device max mtu.

Reviewed-by: Eric Dumazet <edumazet@google.com>

Hi Wang,

On Mon, Oct 14, 2024 at 4:43 PM Wang Hai <wanghai38@huawei.com> wrote:
> The rtsn_start_xmit() returns NETDEV_TX_OK without freeing skb
> in case of skb->len being too long, add dev_kfree_skb_any() to fix it.
>
> Fixes: b0d3969d2b4d ("net: ethernet: rtsn: Add support for Renesas Ethernet-TSN")
> Signed-off-by: Wang Hai <wanghai38@huawei.com>

Thanks for your patch!

> --- a/drivers/net/ethernet/renesas/rtsn.c
> +++ b/drivers/net/ethernet/renesas/rtsn.c
> @@ -1057,6 +1057,7 @@ static netdev_tx_t rtsn_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>         if (skb->len >= TX_DS) {
>                 priv->stats.tx_dropped++;
>                 priv->stats.tx_errors++;
> +               dev_kfree_skb_any(skb);
>                 goto out;
>         }

Does the same apply to the skb_put_padto() failure path below?

drivers/net/ethernet/renesas/rtsn.c-    if (skb_put_padto(skb, ETH_ZLEN))
drivers/net/ethernet/renesas/rtsn.c-            goto out;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On Tue, Oct 15, 2024 at 8:58 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Wang,
>
> On Mon, Oct 14, 2024 at 4:43 PM Wang Hai <wanghai38@huawei.com> wrote:
> > The rtsn_start_xmit() returns NETDEV_TX_OK without freeing skb
> > in case of skb->len being too long, add dev_kfree_skb_any() to fix it.
> >
> > Fixes: b0d3969d2b4d ("net: ethernet: rtsn: Add support for Renesas Ethernet-TSN")
> > Signed-off-by: Wang Hai <wanghai38@huawei.com>
>
> Thanks for your patch!
>
> > --- a/drivers/net/ethernet/renesas/rtsn.c
> > +++ b/drivers/net/ethernet/renesas/rtsn.c
> > @@ -1057,6 +1057,7 @@ static netdev_tx_t rtsn_start_xmit(struct sk_buff *skb, struct net_device *ndev)
> >         if (skb->len >= TX_DS) {
> >                 priv->stats.tx_dropped++;
> >                 priv->stats.tx_errors++;
> > +               dev_kfree_skb_any(skb);
> >                 goto out;
> >         }
>
> Does the same apply to the skb_put_padto() failure path below?
>
> drivers/net/ethernet/renesas/rtsn.c-    if (skb_put_padto(skb, ETH_ZLEN))
> drivers/net/ethernet/renesas/rtsn.c-            goto out;

In case of error, skb_put_padto() frees the skb.

/**
 * skb_put_padto - increase size and pad an skbuff up to a minimal size
 * @skb: buffer to pad
 * @len: minimal length
 *
 * Pads up a buffer to ensure the trailing bytes exist and are
 * blanked. If the buffer already contains sufficient data it
 * is untouched. Otherwise it is extended. Returns zero on
 * success. The skb is freed on error.
 */
static inline int __must_check skb_put_padto(struct sk_buff *skb,
unsigned int len)
{
return __skb_put_padto(skb, len, true);
}

Hello Wang,

Thanks for finding this.

On 2024-10-14 22:42:50 +0800, Wang Hai wrote:
> The rtsn_start_xmit() returns NETDEV_TX_OK without freeing skb
> in case of skb->len being too long, add dev_kfree_skb_any() to fix it.
> 
> Fixes: b0d3969d2b4d ("net: ethernet: rtsn: Add support for Renesas Ethernet-TSN")
> Signed-off-by: Wang Hai <wanghai38@huawei.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/net/ethernet/renesas/rtsn.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ethernet/renesas/rtsn.c b/drivers/net/ethernet/renesas/rtsn.c
> index f9f63c61d792..6b3f7fca8d15 100644
> --- a/drivers/net/ethernet/renesas/rtsn.c
> +++ b/drivers/net/ethernet/renesas/rtsn.c
> @@ -1057,6 +1057,7 @@ static netdev_tx_t rtsn_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>  	if (skb->len >= TX_DS) {
>  		priv->stats.tx_dropped++;
>  		priv->stats.tx_errors++;
> +		dev_kfree_skb_any(skb);
>  		goto out;
>  	}
>  
> -- 
> 2.17.1
> 

-- 
Kind Regards,
Niklas Söderlund