[PATCH net] net: stmmac: Complete meta data only when enabled

[Stanislav Fomichev]

On Thu, Feb 22, 2024 at 1:45 AM Kurt Kanzenbach <kurt at linutronix.de> wrote:
>
> Currently using XDP/ZC sockets on stmmac results in a kernel crash:
>
> |[  255.822584] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> |[...]
> |[  255.822764] Call trace:
> |[  255.822766]  stmmac_tx_clean.constprop.0+0x848/0xc38
>
> The program counter indicates xsk_tx_metadata_complete(). However, this
> function shouldn't be called unless metadata is actually enabled.
>
> Tested on imx93 without XDP, with XDP and with XDP/ZC.
>
> Fixes: 1347b419318d ("net: stmmac: Add Tx HWTS support to XDP ZC")
> Suggested-by: Serge Semin <fancer.lancer at gmail.com>
> Signed-off-by: Kurt Kanzenbach <kurt at linutronix.de>
> Tested-by: Serge Semin <fancer.lancer at gmail.com>
> Link: https://lore.kernel.org/netdev/87r0h7wg8u.fsf@kurt.kurt.home/

Acked-by: Stanislav Fomichev <sdf at google.com>

LGTM, thanks!

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e80d77bd9f1f..8b77c0952071 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2672,7 +2672,8 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue,
>                         }
>                         if (skb) {
>                                 stmmac_get_tx_hwtstamp(priv, p, skb);
> -                       } else {
> +                       } else if (tx_q->xsk_pool &&
> +                                  xp_tx_metadata_enabled(tx_q->xsk_pool)) {
>                                 struct stmmac_xsk_tx_complete tx_compl = {
>                                         .priv = priv,
>                                         .desc = p,
>
> ---
> base-commit: 603ead96582d85903baec2d55f021b8dac5c25d2
> change-id: 20240222-stmmac_xdp-585ebf1680b3
>
> Best regards,
> --
> Kurt Kanzenbach <kurt at linutronix.de>
>