[PATCH bpf-next] selftests/bpf: fix the incorrect verification of port numbers.

[thinker.li@gmail.com]

From: Kui-Feng Lee <thinker.li@gmail.com>

Check port numbers before calling htons().

According to Dan Carpenter's report, Smatch identified incorrect port
number checks. It is expected that the returned port number is an integer,
with negative numbers indicating errors. However, the value was mistakenly
verified after being translated by htons().

Fixes: 8a8c2231cab2 ("selftests/bpf: fix the incorrect verification of port numbers.")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/bpf/cafd6585-d5a2-4096-b94f-7556f5aa7737@moroto.mountain/
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c b/tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c
index 95bab61a1e57..0df95bc88a9b 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_tcp_skb.c
@@ -110,11 +110,13 @@ static int connect_client_server_v6(int client_fd, int listen_fd)
 		.sin6_family = AF_INET6,
 		.sin6_addr = IN6ADDR_LOOPBACK_INIT,
 	};
+	int port;
 	int err;
 
-	addr.sin6_port = htons(get_sock_port_v6(listen_fd));
-	if (addr.sin6_port < 0)
+	port = get_sock_port_v6(listen_fd);
+	if (port < 0)
 		return -1;
+	addr.sin6_port = htons(port);
 
 	err = connect(client_fd, (struct sockaddr *)&addr, sizeof(addr));
 	if (err < 0) {
-- 
2.34.1