[PATCH net] net: ti: icssg-prueth: Fix link-local addresses being forwarded out of slave ports

[Paolo Abeni]

On 7/1/26 1:25 PM, MD Danish Anwar wrote:
> Link-local multicast addresses (01:80:c2:00:00:0x) must only be
> delivered to the host port (P0) and must not be forwarded out of
> the physical slave ports. icssg_fdb_add_del() was programming these
> addresses with P1/P2 membership bits set, causing the firmware to
> forward them out of slave ports.
> 
> Clear P1/P2 membership and set only P0 membership when
> is_link_local_ether_addr() returns true.
> 
> Fixes: 487f7323f39a ("net: ti: icssg-prueth: Add helper functions to configure FDB")
> Signed-off-by: MD Danish Anwar <danishanwar at ti.com>
> ---
>  drivers/net/ethernet/ti/icssg/icssg_config.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_config.c b/drivers/net/ethernet/ti/icssg/icssg_config.c
> index 3f8237c17d099..04a81402e3f3c 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_config.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_config.c
> @@ -732,6 +732,16 @@ int icssg_fdb_add_del(struct prueth_emac *emac, const unsigned char *addr,
>  	u8 fid = vid;
>  	int ret;
>  
> +	/* Link-local addresses (01:80:c2:00:00:0x) must only be delivered to
> +	 * the host port (P0). Clear P1/P2 membership to prevent the firmware
> +	 * from forwarding them out of the physical slave ports.
> +	 */
> +	if (is_link_local_ether_addr(addr)) {
> +		fid_c2 |= ICSSG_FDB_ENTRY_P0_MEMBERSHIP;
> +		fid_c2 &= ~(ICSSG_FDB_ENTRY_P1_MEMBERSHIP |
> +			    ICSSG_FDB_ENTRY_P2_MEMBERSHIP);
> +	}

Sashiko gemeni mentioned it could be safer to reject entirely wrong masks:

https://sashiko.dev/#/patchset/20260701112535.4027920-1-danishanwar%40ti.com

It's not clear to me if the mentioned bad scenario is actually possibly,
please have a look.

/P