[PATCH bpf-next] selftests/bpf: Fix rare segfault in sock_fields prog test

["Jörn-Thorben Hinz" <jthinz@mailbox.tu-berlin.de>]

test_sock_fields__detach() got called with a null pointer here when one
of the CHECKs or ASSERTs up to the test_sock_fields__open_and_load()
call resulted in a jump to the "done" label.

A skeletons *__detach() is not safe to call with a null pointer, though.
This led to a segfault.

Go the easy route and only call test_sock_fields__destroy() which is
null-pointer safe and includes detaching.

Came across this while looking[1] to introduce the usage of
bpf_tcp_helpers.h (included in progs/test_sock_fields.c) together with
vmlinux.h.

[1] https://lore.kernel.org/bpf/629bc069dd807d7ac646f836e9dca28bbc1108e2.camel@mailbox.tu-berlin.de/

Fixes: 8f50f16ff39d ("selftests/bpf: Extend verifier and bpf_sock tests for dst_port loads")
Signed-off-by: Jörn-Thorben Hinz <jthinz@mailbox.tu-berlin.de>
---
 tools/testing/selftests/bpf/prog_tests/sock_fields.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sock_fields.c b/tools/testing/selftests/bpf/prog_tests/sock_fields.c
index 9d211b5c22c4..7d23166c77af 100644
--- a/tools/testing/selftests/bpf/prog_tests/sock_fields.c
+++ b/tools/testing/selftests/bpf/prog_tests/sock_fields.c
@@ -394,7 +394,6 @@ void serial_test_sock_fields(void)
 	test();
 
 done:
-	test_sock_fields__detach(skel);
 	test_sock_fields__destroy(skel);
 	if (child_cg_fd >= 0)
 		close(child_cg_fd);
-- 
2.30.2