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 <martin.lau@linux.dev>]

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.