On Tue, 2022-06-21 at 19:00 +0200, Daniel Borkmann wrote: > On 6/21/22 9:01 AM, 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); > > > > Great catch! I think we have similar detach & destroy pattern in a > number > of places in selftests. Did a quick grep for other __detach(skel) calls yesterday. I didn’t find similar places that were too obviously problematic. > > Should we rather just move the label, like: Sure, if you would prefer that? Let me know. Since this test—unlike others—does not attach the skel twice (like prog_tests/test_lsm.c), or reads/asserts values from the skel’s data sections between detach and destroy (like prog_tests/timer.c), my thought was to just let __destroy() do all the clean-up. > > diff --git a/tools/testing/selftests/bpf/prog_tests/sock_fields.c > b/tools/testing/selftests/bpf/prog_tests/sock_fields.c > index 9d211b5c22c4..e8a947241e37 100644 > --- a/tools/testing/selftests/bpf/prog_tests/sock_fields.c > +++ b/tools/testing/selftests/bpf/prog_tests/sock_fields.c > @@ -393,8 +393,8 @@ void serial_test_sock_fields(void) > > test(); > > -done: > test_sock_fields__detach(skel); > +done: > test_sock_fields__destroy(skel); > if (child_cg_fd >= 0) > close(child_cg_fd);
