Re: [PATCH v10 bpf-next 1/2] bpf: test_run: Fix the null pointer dereference issue in bpf_lwt_xmit_push_encap

[Martin KaFai Lau]

On 3/4/26 2:33 AM, Leon Hwang wrote:
> > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> > index 178c4738e63b..565fe8cbcdc9 100644
> > --- a/net/bpf/test_run.c
> > +++ b/net/bpf/test_run.c
> > @@ -1156,6 +1156,20 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> >   		skb->ip_summed = CHECKSUM_COMPLETE;
> >   	}
> >   
> > +	if (prog->type == BPF_PROG_TYPE_LWT_XMIT) {
> > +		if (ipv6_bpf_stub) {
> > +#if IS_ENABLED(CONFIG_IPV6)
> > +			dst_hold(&net->ipv6.ip6_null_entry->dst);
> > +			skb_dst_set(skb, &net->ipv6.ip6_null_entry->dst);
> > +#endif
> > +		} else {
> > +			/* For CONFIG_IPV6=n, ipv6_bpf_stub is NULL */
> > +			pr_warn_once("Please test this program with the IPv6 module enabled\n");
> > +			ret = -EOPNOTSUPP;
> > +			goto out;
> > +		}
> > +	}
> > +
> NIT: it would be more readable to handle the error path first.
>
> if (prog->type == BPF_PROG_TYPE_LWT_XMIT) {
> 	if (!ipv6_bpf_stub) {
> 		pr_warn_once("...");
> 		ret = -EOPNOTSUPP;
> 		goto out;
> 	}
> #if IS_ENABLED(CONFIG_IPV6)
> 	dst_hold();
> 	skb_dst_set();
> #endif

I have adapted this change and applied. Thanks.