Re: [PATCH v2 net] net: dsa: Discard frames from unused ports

[Florian Fainelli <f.fainelli@gmail.com>]

On 04/07/2018 11:37 AM, Andrew Lunn wrote:
> The Marvell switches under some conditions will pass a frame to the
> host with the port being the CPU port. Such frames are invalid, and
> should be dropped. Not dropping them can result in a crash when
> incrementing the receive statistics for an invalid port.
> 
> Reported-by: Chris Healy <cphealy@gmail.com>
> Fixes: 91da11f870f0 ("net: Distributed Switch Architecture protocol support")
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

It looks like the stable scripts now test build against several kernel
versions so we should be able to know which stable versions need a
specific fix that does not involve dsa_master_find_slave().

Thanks Andrew!

> ---
> v2:
> Use an earlier revision for the fixes tag.
> Add unlikely annotation
> ---
>  net/dsa/dsa_priv.h | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index 70de7895e5b8..053731473c99 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -126,6 +126,7 @@ static inline struct net_device *dsa_master_find_slave(struct net_device *dev,
>  	struct dsa_port *cpu_dp = dev->dsa_ptr;
>  	struct dsa_switch_tree *dst = cpu_dp->dst;
>  	struct dsa_switch *ds;
> +	struct dsa_port *slave_port;
>  
>  	if (device < 0 || device >= DSA_MAX_SWITCHES)
>  		return NULL;
> @@ -137,7 +138,12 @@ static inline struct net_device *dsa_master_find_slave(struct net_device *dev,
>  	if (port < 0 || port >= ds->num_ports)
>  		return NULL;
>  
> -	return ds->ports[port].slave;
> +	slave_port = &ds->ports[port];
> +
> +	if (unlikely(slave_port->type != DSA_PORT_TYPE_USER))
> +		return NULL;
> +
> +	return slave_port->slave;
>  }
>  
>  /* port.c */
> 

-- 
Florian