Re: [PATCH net 1/2] net: dst_metadata: fix IP_DF bit not extracted from tunnel headers

[Ido Schimmel]

On Fri, Sep 05, 2025 at 03:30:55PM +0200, Ilya Maximets wrote:
> @@ -220,9 +221,15 @@ static inline struct metadata_dst *ip_tun_rx_dst(struct 
> sk_buff *skb,
>                                                int md_size)
>  {
>       const struct iphdr *iph = ip_hdr(skb);
> +     struct metadata_dst *tun_dst;
> +
> +     tun_dst = __ip_tun_set_dst(iph->saddr, iph->daddr, iph->tos, iph->ttl,
> +                                0, flags, tunnel_id, md_size);
>  
> -     return __ip_tun_set_dst(iph->saddr, iph->daddr, iph->tos, iph->ttl,
> -                             0, flags, tunnel_id, md_size);
> +     if (iph->frag_off & htons(IP_DF))
> +             __set_bit(IP_TUNNEL_DONT_FRAGMENT_BIT,
> +                       tun_dst->u.tun_info.key.tun_flags);

Shouldn't you check that tun_dst isn't NULL?

> +     return tun_dst;
>  }