Re: [PATCH net] lan966x: Fix crash when adding interface under a lag

[Michal Swiatkowski]

On Mon, Feb 05, 2024 at 09:07:56AM +0100, Horatiu Vultur wrote:
> There is a crash when adding one of the lan966x interfaces under a lag
> interface. The issue can be reproduced like this:
> ip link add name bond0 type bond miimon 100 mode balance-xor
> ip link set dev eth0 master bond0
> 
> The reason is because when adding a interface under the lag it would go
> through all the ports and try to figure out which other ports are under
> that lag interface. And the issue is that lan966x can have ports that are
> NULL pointer as they are not probed. So then iterating over these ports
> it would just crash as they are NULL pointers.
> The fix consists in actually checking for NULL pointers before accessing
> something from the ports. Like we do in other places.
> 
> Fixes: cabc9d49333d ("net: lan966x: Add lag support for lan966x")
> Signed-off-by: Horatiu Vultur <horatiu.vultur@xxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/microchip/lan966x/lan966x_lag.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_lag.c b/drivers/net/ethernet/microchip/lan966x/lan966x_lag.c
> index 41fa2523d91d3..89a2c3176f1da 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_lag.c
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_lag.c
> @@ -37,19 +37,24 @@ static void lan966x_lag_set_aggr_pgids(struct lan966x *lan966x)
>  
>  	/* Now, set PGIDs for each active LAG */
>  	for (lag = 0; lag < lan966x->num_phys_ports; ++lag) {
> -		struct net_device *bond = lan966x->ports[lag]->bond;
> +		struct lan966x_port *port = lan966x->ports[lag];
>  		int num_active_ports = 0;
> +		struct net_device *bond;
>  		unsigned long bond_mask;
>  		u8 aggr_idx[16];
>  
> -		if (!bond || (visited & BIT(lag)))
> +		if (!port || !port->bond || (visited & BIT(lag)))
>  			continue;
>  
> +		bond = lan966x->ports[lag]->bond;
Why not bond = port->bond?

>  		bond_mask = lan966x_lag_get_mask(lan966x, bond);
>  
>  		for_each_set_bit(p, &bond_mask, lan966x->num_phys_ports) {
>  			struct lan966x_port *port = lan966x->ports[p];
>  
> +			if (!port)
> +				continue;
> +
>  			lan_wr(ANA_PGID_PGID_SET(bond_mask),
>  			       lan966x, ANA_PGID(p));
>  			if (port->lag_tx_active)
> -- 
> 2.34.1
> 
Only nit, otherwise:
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>

Thanks,
Michal