netdev - Re: [PATCH net] rtnetlink: NUL-terminate IFLA_PHYS_PORT

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Date:   Thu, 4 May 2017 10:14:13 -0600
From:   David Ahern <dsahern@...il.com>
To:     Michal Schmidt <mschmidt@...hat.com>, netdev@...r.kernel.org
Cc:     Thomas Haller <thaller@...hat.com>
Subject: Re: [PATCH net] rtnetlink: NUL-terminate IFLA_PHYS_PORT_NAME string

On 5/4/17 8:48 AM, Michal Schmidt wrote:
> IFLA_PHYS_PORT_NAME is a string attribute, so terminate it with \0.
> Otherwise libnl3 fails to validate netlink messages with this attribute.
> "ip -detail a" assumes too that the attribute is NUL-terminated when
> printing it. It often was, due to padding.
> 
> I noticed this as libvirtd failing to start on a system with sfc driver
> after upgrading it to Linux 4.11, i.e. when sfc added support for
> phys_port_name.
> 
> Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
> ---
>  net/core/rtnetlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index c4e84c5582..69daf393cb 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -1056,7 +1056,7 @@ static int rtnl_phys_port_name_fill(struct sk_buff *skb, struct net_device *dev)
>  		return err;
>  	}
>  
> -	if (nla_put(skb, IFLA_PHYS_PORT_NAME, strlen(name), name))
> +	if (nla_put_string(skb, IFLA_PHYS_PORT_NAME, name))
>  		return -EMSGSIZE;
>  
>  	return 0;
> 

Thanks for fixing.