On Tue, 2022-06-21 at 12:54 -0700, John Fastabend wrote: > Jörn-Thorben Hinz wrote: > > 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@xxxxxxxxxxxxxxxxxxxx/ > > > > Fixes: 8f50f16ff39d ("selftests/bpf: Extend verifier and bpf_sock > > tests for dst_port loads") > > Signed-off-by: Jörn-Thorben Hinz <jthinz@xxxxxxxxxxxxxxxxxxxx> > > --- > > 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 > > > > But we should still call __detach(skel) after the !skel check > is done I assume. If I’m not mistaken, that’s not necessary for a proper clean-up. It should be more of a stylistic question. See the parallel message from Daniel (and replies). test_sock_fields__detach() directly translates to bpf_object__detach_skeleton(). test_sock_fields__destroy() basically translates to bpf_object__destroy_skeleton(), including a null-ptr check. But bpf_object__destroy_skeleton() calls bpf_object__detach_skeleton() as its first step. So calling __detach()/__detach_skeleton() explicitly and separately is not necessary for a clean exit, if not otherwise required. > So rather than remove it should add a new label > and jump to that, > > > done: > test_sock_fields__detach(); > done_no_skel: > test_sock_fields__destroy()
