Re: [bug report] selftests/bpf: Verify that the cgroup_skb filters receive expected packets.

[Kui-Feng Lee <sinquersw@gmail.com>]

On 8/3/23 12:52, Kui-Feng Lee wrote:
> 
> 
> On 7/31/23 00:27, Dan Carpenter wrote:
>> Hello Kui-Feng Lee,
>>
>> The patch 539c7e67aa4a: "selftests/bpf: Verify that the cgroup_skb
>> filters receive expected packets." from Jun 23, 2023 (linux-next),
>> leads to the following Smatch static checker warning:
>>
>>     ./tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c:116 
>> connect_client_server_v6()
>>     warn: unsigned 'addr.sin6_port' is never less than zero.
>>
>> ./tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c
>>      107 static int connect_client_server_v6(int client_fd, int 
>> listen_fd)
>>      108 {
>>      109         struct sockaddr_in6 addr = {
>>      110                 .sin6_family = AF_INET6,
>>      111                 .sin6_addr = IN6ADDR_LOOPBACK_INIT,
>>      112         };
>>      113         int err;
>>      114
>>      115         addr.sin6_port = htons(get_sock_port_v6(listen_fd));
>> --> 116         if (addr.sin6_port < 0)
>>                      ^^^^^^^^^^^^^^^^^^
>> Impossible and also it doesn't make sense to compare network endian data
>> with < 0.
> 
> Hi Dan,
> 
> Thank you for pointing it out. It should check the returned value
> of get_sock_port_v6() before calling htons(). I will send a patch
> to fix it asap.

Could you show me how to run Smatch againt bpf selftests?

> 
> 
>>
>>      117                 return -1;
>>      118
>>      119         err = connect(client_fd, (struct sockaddr *)&addr, 
>> sizeof(addr));
>>      120         if (err < 0) {
>>      121                 perror("connect");
>>      122                 return -1;
>>      123         }
>>      124
>>      125         return 0;
>>      126 }
>>
>> regards,
>> dan carpenter
>>